HCF_LIT-039 Rev. 7.1
Date of Publication: September 27, 2013
Document Distribution / Maintenance Control / Document Approval
To obtain information concerning document distribution control, maintenance control, and document approval pleasecontact the HART Communication Foundation (HCF) at the address shown below.
Copyright © 2013 (1997-2012) HART Communication Foundation
This document contains copyrighted material and may not be reproduced in any fashion without the written permission of
the HART Communication Foundation.
Trademark Information
HART® and WirelessHART® are registered trademarks of the HART Communication Foundation, Austin, Texas, USA. Any useof the term HART hereafter in this document, or in any document referenced by this document, implies the registeredtrademark. All other trademarks used in this or referenced documents are trademarks of their respective companies. For
more information contact the HCF Staff at the address below.

HART Communication Foundation
9390 Research Boulevard
Suite I-350
Austin, TX 78759, USA
Voice: (512) 794-0369
FAX: (512) 794-3904

www.hartcomm.org
Intellectual Property Rights
The HCF does not knowingly use or incorporate any information or data into the HART Protocol Standards which the HCF
does not own or have lawful rights to use. Should the HCF receive any notification regarding the existence of any
conflicting Private IPR, the HCF will review the disclosure and either (a) determine there is no conflict; (b) resolve theconflict with the IPR owner; or (c) modify the standard to remove the conflicting requirement. In no case does the HCF
encourage implementers to infringe on any individual's or organization's IPR.

Acknowledgement of contributions by Dresser Masonelian, Emerson and Moore Industries International, Inc.

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Table of Contents
PREFACE __________________________________________________________________________ 8
THEORY OF OPERATION ______________________________________________________________ 9
Communication Modes _____________________________________________________________ 10
Request-Response Mode _________________________________________________________________ 10
Burst Mode ____________________________________________________________________________ 10

Frequency Shift Keying (FSK) _________________________________________________________ 11
Phase Shift Keying (PSK) ____________________________________________________________ 11
HART Networks ___________________________________________________________________ 12
Point-to-Point __________________________________________________________________________ 12
Multi-drop _____________________________________________________________________________ 13
Split Ranging Control Valves_______________________________________________________________ 14
Control in Field Devices __________________________________________________________________ 16
HART Field Controller Implementation ______________________________________________________ 17

HART Commands __________________________________________________________________ 18
Universal ______________________________________________________________________________ 18
Common Practice _______________________________________________________________________ 18
Device Specific _________________________________________________________________________ 18

WirelessHART _____________________________________________________________________ 21
Co-Existence ___________________________________________________________________________ 21
Channel Hopping________________________________________________________________________ 22
Time Division Multiplexing ________________________________________________________________ 22
Power Modulation ______________________________________________________________________ 22
Direct Sequence Spread Spectrum __________________________________________________________ 22
Mesh Networking _______________________________________________________________________ 23
Blacklisting and Channel Assessment _______________________________________________________ 23
How It Works __________________________________________________________________________ 23
Components ___________________________________________________________________________ 25
Getting Started _________________________________________________________________________ 25
3

Benefits of HART Communication _____________________________________________________ 29
Improved Plant Operations __________________________________________________________ 30
Cost Savings in Commissioning ____________________________________________________________ 30
Cost Savings in Installation ________________________________________________________________ 30
Digital Communication ___________________________________________________________________ 30
Improved Measurement Quality ___________________________________________________________ 32
Cost Savings in Maintenance ______________________________________________________________ 33

Operational Flexibility ______________________________________________________________ 34
Instrumentation Investment Protection ________________________________________________ 35
Compatibility of HART Revisions ___________________________________________________________ 35

GETTING THE MOST OUT OF HART SYSTEMS ____________________________________________ 36
Wiring and Installation _____________________________________________________________ 37
Cable Length ___________________________________________________________________________ 37

Intrinsic Safety ____________________________________________________________________ 38
Intrinsic Safety Devices ___________________________________________________________________ 38
Designing an IS System Using Shunt-Diode Barriers ____________________________________________ 38
Designing an IS System Using Isolators ______________________________________________________ 39
Multi-drop IS Networks __________________________________________________________________ 40
IS Output Loops_________________________________________________________________________ 40
IS Certification Considerations _____________________________________________________________ 40
IS Network Cable Length Calculations _______________________________________________________ 40
Safety Integrity Level (SIL) ________________________________________________________________ 41

HART Multi-drop Networks __________________________________________________________ 42
Multi-drop with HART Field Controllers _____________________________________________________ 43
Application Considerations _______________________________________________________________ 44
Configuring Devices for Multi-drop Operation ________________________________________________ 44

Control System Interfaces ___________________________________________________________ 45
HART I/O Subsystems ____________________________________________________________________ 45
HART I/O for Multi-drop Support ___________________________________________________________ 45
HART I/O for Burst Mode Support __________________________________________________________ 45
Data Handling __________________________________________________________________________ 46
4

Pass-through Feature ____________________________________________________________________ 46
Gateways______________________________________________________________________________ 46
SCADA/RTU Systems_____________________________________________________________________ 46

Multiplexers ______________________________________________________________________ 47
Multiplexers – Remote I/O as the Primary I/O System __________________________________________ 47
Parallel Monitoring with a Multiplexer ______________________________________________________ 48
HART Over PROFIBUS ____________________________________________________________________ 50

Reading HART Data into Non-HART Systems ____________________________________________ 51
Commissioning HART Networks ______________________________________________________ 54
Device Verification ______________________________________________________________________ 54
Loop Integrity Check _____________________________________________________________________ 54
As-Installed Record Keeping _______________________________________________________________ 54

Device Status and Diagnostics ________________________________________________________ 55
Connecting a PC to a HART Device or Network ________________________________________________ 56

INDUSTRY APPLICATIONS ___________________________________________________________ 57
APPLICATION _____________________________________________________________________ 59
HART Multi-drop Network for Tank Level and Inventory Management _______________________ 59
APPLICATION _____________________________________________________________________ 60
Multi-drop for Tank Farm Monitoring __________________________________________________ 60
APPLICATION _____________________________________________________________________ 61
Underground Petroleum Storage Using HART for Accuracy ________________________________ 61
Lonza Chooses HART Technology for Quick Validation and Commissioning ____________________ 62
Genentech Uses HART to Reduce Life cycle Device Management, Installation and Start-Up Costs __ 65
DuPont Uses HART Data to Satisfy Safety Interlock System Valve Test Requirements ___________ 70
Eastman Chemical Uses HART Pressure Transmitter to Achieve Cost-Effective Maintenance ______ 76
Monsanto Uses HART to Optimize Asset Reliability and Improve Productivity _________________ 78
Sasol Solvents Uses HART to Improve Asset Management _________________________________ 84
ORBCOMM Uses HART Communication in Satellites ______________________________________ 91
to Transfer Data ___________________________________________________________________ 91
BP Canada Energy Uses HART Communication to Improve Process Control and Save Money______ 94
5INRA Uses HART Communication to Gaining High Resolution Process Values __________________ 99
Cebrace Uses HART Interface for Asset Management Integration __________________________ 102
Gas Pipeline Company Uses HART to Modernize Operations and Save $1.25 million Annually____ 106
HART-to-Ethernet Gateway: Two Diverse Applications, One Solution _______________________ 109
REFINERY – MEXICO ____________________________________________________________________ 109
WHEAT MILL – GERMANY________________________________________________________________ 111

PDVSA Uses HART Technology to Streamline Preventive Maintenance Process________________ 112
Shell Uses HART Communication to Improve Nigerian Plant Operations _____________________ 115
Statoil Uses HART Communication to Deliver Natural Gas from Under the Sea ________________ 118
Clariant Uses HART Technology to Solve Major Production Problem ________________________ 125
BP Cooper River Uses HART Diagnostics to Save on Maintenance and Increase Productivity _____ 129
New York Power Utility Uses HART to Reduce Costs and Improve Reliability __________________ 133
Ohio State University Uses HART to Reduce Risk to Product _______________________________ 135
Appleton Paper Uses HART to Improve Asset Management and Saves $40,000 on Wiring Alone _ 140
Fraser Papers Gains Predictive Maintenance Edge Using HART Valve Positioning _____________ 143
Swedish Pulp and Paper Plant Uses HART Technology to Improve Plant Availability ___________ 146
Brazilian Steel Plant Uses HART Communication to Reduce Data Retrieval Time ______________ 148
AECOM Canada Uses HART Communication to Keep Waterways Clean ______________________ 151
Detroit Water Deploys HART to Improve Customer Satisfaction ____________________________ 154
Milwaukee Sewerage District Uses HART to Support Safer Sewer System ____________________ 164
Persian Gulf Company Uses HART Communication to Improve Water Conversion Process _______ 166
Sluvad Water Treatment Works Employs HART Protocol’s Multi-Drop Network Capability for
Flexibility, Redundancy, Cost Savings _________________________________________________ 169
WirelessHART Applications _________________________________________________________ 172
WirelessHART Network Helps Steel Mill Increase Production and Reduce Costs _______________ 173
Electric Utility Uses WirelessHART Communication to Improve Performance Efficiency _________ 174
WirelessHART at BASF _____________________________________________________________ 176
Where to Get Information __________________________________________________________ 180
APPENDIX A: HART Checklist ________________________________________________________ 181
APPENDIX B: HART Field Control _____________________________________________________ 185
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APPENDIX C: Technical Information __________________________________________________ 187
GLOSSARY _______________________________________________________________________ 189

7

PREFACE
In today’s competitive environment, all companies seek to reduce operation costs, deliver products
rapidly and improve product quality. The HART® (Highway Addressable Remote Transducer)
Communication Protocol directly contributes to these business goals by providing cost savings in:• Commissioning and installation• Plant operations and improved quality• Maintenance
The HART Application Guide has been created by the HART Communication Foundation to provide users
of HART products with the information necessary to obtain the full benefits of HART digital
instrumentation. The HART Communication Protocol is an open standard owned by the HCF member
companies (membership includes 290 companies worldwide as of 09/2013). Products that use the HART
protocol to provide both analog 4-20A and digital signals provide flexibility not available with any othercommunication technology.
The following four sections of this guide provide an understanding of how the HART technology works,
insight on how to apply various features of the technology, and specific examples of applications
implemented by HART Protocol users around the world:• Theory of Operation• Benefits of HART Communication• Getting the Most out of HART Systems• Industry Applications

8

THEORY OF OPERATION
The following sections explain the basic principles behind the operation of HART instruments andnetworks:• Communication Modes• Frequency Shift Keying• HART Networks• HART Commands

9

COMMUNICATION MODES
The digital communication signal has a response time of approximately 2-3 data updates per second
without interrupting the analog signal. A minimum loop impedance of 230 Ω is required forcommunication.

REQUEST-RESPONSE MODE
HART is typically a request-response communication protocol, which means that during normal
operation (2-3 data updates per second) each field device communication is initiated by a hostcommunication device. Two hosts can connect to each HART loop. The primary host is generally:a) a distributed control system (DCS),b) a programmable logic controller (PLC), orc) a personal computer (PC).
The secondary host can be a handheld terminal or another PC. Field devices include transmitters,
actuators and controllers that respond to commands from the primary or secondary host.

BURST MODE
Some HART devices support the optional burst communication mode. Burst mode enables fastercommunication (3-4 data updates per second). In burst mode, the host instructs the field device tocontinuously broadcast a standard HART reply message (e.g., the value of the process variable). The host
receives the message at the higher rate until it instructs the device to stop bursting.

Use burst mode to enable more than one passive
HART device to listen to communications on the HART loop

10

FREQUENCY SHIFT KEYING (FSK)The HART Communication Protocol is based on the Bell 202 telephone communication standard andoperates using the frequency shift keying (FSK) principle. The digital signal is made up of two
frequencies: 1,200 Hz and 2,200 Hz representing bits 1 and 0, respectively. Sine waves of these two
frequencies are superimposed on the direct current (dc) analog signal cables to provide simultaneous
analog and digital communications (Fig 1). Because the average value of the FSK signal is always zero,
the 4-20mA analog signal is not affected.

Figure 1 – Simultaneous analog and digital communications

PHASE SHIFT KEYING (PSK)PSK Physical Layer—a higher speed physical layer option—is available in the HART 6 and HART 7 versionsof the HART Protocol. PSK supports significantly faster communications with standard
command/response throughput of up to 10-12 transactions per second simultaneous with the 4-20mA
signal. This is an approved specification but (at the time of publication) no commercially produced chip
is available to support implementation in 2-wire devices.

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HART NETWORKS
HART devices can operate in one of two network configurations—Point-to-Point or Multi-drop.

POINT-TO-POINT
In point-to-point mode, the 4-20mA signal is used to communicate one process variable, while
additional process variables, configuration parameters, and other device data are transferred digitallyusing the HART Protocol (Fig 2). The 4-20mA analog signal is not affected by the HART signal and can beused for control. The HART Communication digital signal gives access to secondary variables and otherdata that can be used for operations, commissioning, maintenance and diagnostic purposes.

Figure 2 – Point-to-Point Communication

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MULTI-DROP
The multi-drop mode of operation requires only a single pair of wires and, if applicable, safety barriers
and an auxiliary power supply for up to 15 field devices (HART 5) or 62 field devices (HART 7) (Fig 3). Allprocess values are transmitted digitally. In multi-drop mode, all field device polling addresses must be
unique in a range of 1-63 (depending on the HART Protocol Revision) and the current through eachdevice is fixed to a minimum value (typically 4mA).
Use multi-drop connection for supervisory control installations that are widely spaced such as pipelines,
custody transfer stations, and tank farms.

Figure 3 – Multi-drop Communication

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SPLIT RANGING CONTROL VALVES
Split range control is a single control loop divided into two or more independent final control elements
such as valves acting in different directions or in different steps. There are many ways to implement a
split range control: software, valve calibration or by connecting two or more positioners to a single
control signal (usually 4-20mA).
HART-enabled intelligent valve positioners provide the easiest way to implement a split range control
loop because of the easy-to-use configuration menus available in handheld terminals and the software
configuration tools based on either DDs or DTMs.
With HART Communication the range for each intelligent valve positioner, as well as the control action,
can be set with high precision; for example, air-to-open (ATO) or air-to-close (ATC) among others. Before
proceeding with installation end users should check the following requirements for intelligent valve
positioners:•

5mA minimum current span•

9 VDC minimum power•

At least 18 VDC (typical) available from power source (I/O card) for two valves

A typical split range loop with two valves will be configured as follows:•Intelligent Valve Positioner #1•

Action: ATO (Air to Open)•

Input current range: 4-12mAIntelligent Valve Positioner #2
Action: ATC (Air to Close)
Input Current range: 12-20mA

Position

4mA

12mA

20mA

Valve #1

ClosedFull Open

Full Open

Valve #2

Full Open

Full OpenClosed14

Setting Loop Addresses for Split Range Systems
When more than one positioner is installed in a single current loop, the HART loop address of eachdevice must be set to 1, 2, or 3 (or other non-zero values) to allow a HART master to recognize each
intelligent valve positioner when connected to all three devices on a single current loop. Do not use “0”for any of the positioners. A “0” may cause HART masters to stop searching for additional positioners.

z
Figure 4 – Split Range with Isolators

Most HART-enabled intelligent valve positioners can perform other routines prior to commissioning
such as:•Find Stops•

Tuning•Actuator action•

Shut-off function and limit

Today the use of HART intelligent valve positioners is considered as a “Best Practice” in the industry.

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CONTROL IN FIELD DEVICES
Microprocessor-based smart instrumentation enables control algorithms to be calculated in the fielddevices, close to the process (Figure 5). Some HART transmitters and actuators support control
functionality in the device, which eliminates the need for a separate controller and reduces hardware,
installation, and start-up costs. Accurate closed-loop control becomes possible in areas where it was not
economically feasible before. While the control algorithm uses the analog signal, HART communication
provides the means to monitor the loop and change control set point and parameters.

Figure 5 - Transmitter with PID

Placing control in the field enhances control functionality. Measurement accuracy is maintained because
there is no need to transmit data to a separate controller. Control processing takes place at the highupdate rate of the sensor and provides enhanced dynamic performance.

16HART FIELD CONTROLLER IMPLEMENTATIONA HART field controller takes advantage of the HART Protocol’s simultaneous analog and digital signalingby converting the transmitter’s traditional analog measurement output into a control output. The
analog signal from the smart transmitter (controller) is used to manipulate the field device. The analog
output signal also carries the HART digital signal, which is used for monitoring the process
measurement, making set point changes, and tuning the controller.
The communication rate of the HART Protocol (2-3 updates per second) is generally perceived as too
slow to support closed-loop control in the central host. With control in the field, the control function nolonger depends on the HART Protocol’s communication rate. Instead, the control signal is an analog
output that is updated at a rate that is much faster than typically can be processed in a conventional
control system.
Processing rates vary from 2-20 updates per second, depending on the product. The HART digitalcommunication rate remains sufficient for monitoring the control variable and changing set pointvalues.

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HART COMMANDSThe HART Command Set provides uniform and consistent communication for all field devices. The
command set includes three classes: Universal, Common Practice, and Device Specific (Table 1). Hostapplications may implement any of the necessary commands for a particular application.

UNIVERSAL
All devices using the HART Protocol must recognize and support the universal commands. Universal
commands provide access to information useful in normal operations (e.g., read primary variable andunits).

COMMON PRACTICE
Common Practice commands provide functions implemented by many, but not necessarily all, HART
Communication devices.

DEVICE SPECIFIC
Device Specific commands represent functions that are unique to each field device. These commands
access setup and calibration information, as well as information about the construction of the device.
Information on Device Specific commands is available from device manufacturers.
Device Family Summary Table
Universal Commands

Common Practice Commands

Device Specific Commands

Read manufacturer and device type

Read selection of up to four dynamic
variables

Read or write low-flow cut-off

Read primary variable (PV) and units
Read current output and percent of
range
Read up to four pre-defined dynamic
variables

Write damping time constantWrite device range values
Calibrate (set zero, set span)

Start, stop, or clear totalizer
Read or write density calibration factor
Choose PV (mass, flow, or density)

Set fixed output current

Read or write materials or construction
information

Read or write eight-character tag, 16character descriptor, date

Perform self-test

Trim sensor calibration

Read or write 32-character message

Perform master reset

PID enable

Read device range values, units, anddamping time constant

Trim PV zero

Write PID set point

Write PV unit

Valve characterization

Read or write final assembly number

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Universal Commands

Common Practice Commands

Device Specific Commands

Write polling address

Trim DAC zero and gain

Valve set point

Write transfer function (squareroot/linear)

Travel limits

Write sensor serial number

User units
Local display information

Read or write dynamic variableassignments

Table 1 - HART Commands
This is a partial list of HART commands. See Appendices B, C, and D for more detailed information.
Establishing Communication with a HART Device
Each HART device has a unique 38-bit address that consists of the manufacturer ID code, device typecode and device-unique identifier. A unique address is encoded in each device at the time of
manufacture. A HART master must know the address of a field device in order to communicate
successfully with it. A master can learn the address of a slave device by issuing one of two commands
that cause the slave device to respond with its address:
Command 0, Read Unique Identifier—Command 0 is the preferred method for initiating
communication with a slave device because it enables a master to learn the address of eachslave device without user interaction. Each polling address (0–15) is probed to learn the uniqueaddress for each device.
Command 11, Read Unique Identifier by Tag - Command 11 is useful if there are more than 15
devices in the network or if the network devices were not configured with unique polling
addresses. (Multi-dropping more than 15 devices is possible when the devices are individually
powered and isolated.) Command 11 requires the user to specify the tag numbers to be polled.
Device Description
HART Communication was the first protocol to implement Electronic Device Description Language(EDDL) as its standard. EDDL (IEC 61804-2, EDDL) is the only technology endorsed by the HART
Communication Foundation for configuration of HART devices. It is the most important and widely useddigital communication descriptive language, providing a stable platform for suppliers to define anddocument the capabilities of HART-enabled products in a single, open and consistent format.
Device Descriptions (DDs), created by using Device Description Language, provide the informationneeded by a host application or control system to properly access and display important device
information located in intelligent field devices. The DD includes all of the information needed by a hostapplication to fully communicate with the field device.

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HART EDDL is used to write a DD that combines all of the information needed by the host application
into a single structured file. The DD identifies which Common Practice Commands are supported as wellas the format and structure of all Device Specific Commands.
A DD for a HART field device is roughly equivalent to an electronic data sheet. DDs eliminate the needfor host suppliers to develop and support custom interfaces and drivers. A DD provides a picture of allparameters and functions of a device in a standardized language. HART suppliers have the option of
supplying a DD for their HART field product. If they choose to supply one, the DD will provide
information for a DD-enabled host application to read and write data according to each device’s
procedures.
DD source files for HART devices resemble files written in the C programming language. DD files are
submitted to the HCF for registration in the HCF DD Library. Quality checks are performed on each DD
submitted to ensure specification compliance, to verify that there are no conflicts with DDs alreadyregistered, and to verify operation with standard HART hosts. The HCF DD Library is the central location
for management and distribution of all HART DDs to facilitate use in host applications such as PCs andhandheld terminals.
DDs can be downloaded at www.hartcomm.org.

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WIRELESSHART
As the need for additional process measurements increases, users seek a simple, reliable, secure andcost-effective method to deliver new measurement values to control systems without the need to run
more wires. With process improvements, plant expansions, regulatory requirements and safety levels
demands for additional measurements, users are looking to wireless technology for that solution.
With approximately 40 million HART devices installed and in service worldwide (as of 09/2013), HART
technology is the most widely used field communication protocol for intelligent process
instrumentation. With the additional capability of wireless communication, the legacy of benefits thispowerful technology provides continues to deliver the operational insight users need to remaincompetitive.

CO-EXISTENCE
Co-existence is defined as: The ability of one system to perform a task in a given shared environment
where other systems have an ability to perform their task and may or may not be using the same set ofrules. Successful co-existence is measured by the reliability of each network to deliver its messages tothe desired destination. Therefore, each network must be able to accomplish its objective while notdisrupting the ability of another network to complete its objective.
Problems can occur when two or more packets of information are transmitted at the same time andfrequency so that they “collide” in the same physical space. If networks aren’t designed to minimize or
avoid these occurrences, unreliable communications will result.
There are several techniques that can be used to minimize network interference:•

Channel hopping – changing the frequency channel•

Time Division Multiplexing – varying the time of communications•

Power Modulation – low power transmission•

Direct Sequence Spread Spectrum•

Mesh networking supports large physical space with low power instruments•

Blacklisting and channel assessment

In the data link layer of the WirelessHART specification, packet acknowledgment with automatic retry
assures data is not lost if interference does happen to occur.

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CHANNEL HOPPINGAs specified by IEEE802.15.4, the 2.4 GHZ ISM frequency band is divided into 16 non-overlapping
frequency channels. WirelessHART instruments use a pseudo-random channel hopping sequence toreduce the chance of interference with other networks, such as IEEE802.11b/g (Wi-Fi) which operates inthe same ISM frequency band.
There is a potential of overlap between IEEE802.11g and IEEE802.15.4 radios. Since the 802.11b/g
channels are wider, there are only 3 non-overlapping channels for Wi-Fi networks. A given IEEE802.11
Wi-Fi access point will only use 1 of the 3 non-overlapping channels and will only broadcast periodically,so the channel is not in continuous use.
Pseudo-random channel hopping inherent to WirelessHART instruments ensures that they do not fix onusing a channel being used by an IEEE802.11b/g network for any lengthy period of time. Together withthe other techniques listed above, the probability of interference is minimal either way.

TIME DIVISION MULTIPLEXING
A WirelessHART network utilizes Time Division Multiple Access (TDMA) technology to ensure that only
one instrument is talking on a channel at any given time. This prevents message collisions within the
WirelessHART network. A network is provided with an overall schedule which is divided into 10 msec
timeslots. At any time, only one pair of instruments are communicating on the same frequency channel,
however, it is possible that more than one pair of instruments can communicate at the same time using
different channels. In most cases, only one pair of instruments is communicating in a given timeslot so
the WirelessHART network will not monopolize the frequency spectrum that is shared with otherwireless networks.

POWER MODULATIONThe IEEE802.15.4 radios were chosen because they are relatively low power instruments suited towireless process control applications, as well as being readily available at a reasonable cost. The radios
are used with 10dB amplifiers to allow communication of up to 200m to the next instrument, which inturn can serve as a router to pass the message along. In cases where the full distance is not required,
WirelessHART instruments can transmit at a lower power to reduce the chance of interfering with othernetworks in the ISM frequency band. The lower transmit power of WirelessHART instruments alsomeans that any chance of interfering with an IEEE802.11b/g Wi-Fi network is small.

DIRECT SEQUENCE SPREAD SPECTRUM
Direct Sequence Spread Spectrum (DSSS) technology provides about 8dB of additional gain utilizing
unique coding algorithms. The transmission is spread over the entire frequency of the selected 802.15.4
channel. Devices with the correct decoding information can receive the data while others see thetransmissions as white noise and disregard it. This allows multiple overlapping radio signals to bereceived and understood only by other devices in their own networks.

22

MESH NETWORKINGThe use of mesh networking technology complements the use of the low power IEEE802.15.4 radios.
With mesh networking, instruments do not need to have a direct transmission path to the network
gateway. It is only required that any instrument be able to communicate to any other instrument in themesh network. Each WirelessHART field instrument is capable of routing the message of other
instruments along a route that will ensure the message is received at its ultimate gateway destination.
Mesh networks also provide path redundancy and thus achieve better reliability than if each instrument
were required to have a direct line of sight path to the gateway. The mesh network can adapt tochanging communication and other environmental conditions to find a reliable communication path to
the gateway.
Physical separation of >1m between WirelessHART instruments and Wi-Fi access points is all that isrequired for peaceful coexistence between the two types of wireless networks.
A direct or point-to-point connection to the gateway is also available for applications that might require
faster update speeds.

BLACKLISTING AND CHANNEL ASSESSMENT
In conjunction with channel hopping the WirelessHART network can be configured to avoid specificchannels that are highly utilized by other networks and therefore, are likely to provide interference.
However, because most networks are not loaded continuously this is rarely required.
To further avoid any conflict with other neighboring networks a WirelessHART instrument listens to thefrequency channel prior to transmitting data. If other transmissions are detected the WirelessHART
instrument will back off and attempt the communication in another timeslot on a different frequency.

HOW IT WORKS
WirelessHART is a wireless mesh network communications technology for process automation
applications. It adds wireless capabilities to the HART Protocol while maintaining compatibility withexisting HART devices, commands, and tools.
Each WirelessHART network includes three main elements:•••

Wireless field devices connected to process or plant equipment. These devices can be a device
with WirelessHART built in or an existing installed HART-enabled device with a WirelessHART
adapter attached to it.
Gateways enabling communication between the field devices and host applications connected
to a high-speed backbone or other existing plant communications network.
A Network Manager responsible for configuring the network, scheduling communications
between devices, managing message routes, and monitoring network health. The Network
Manager can be integrated into the gateway, host application, or process automation controller.

The network uses IEEE 802.15.4 compatible radios operating in the 2.4GHz Industrial, Scientific, andMedical radio band. The radios employ direct-sequence spread spectrum technology and channel

23

hopping for communication security and reliability, as well as TDMA synchronized, latency-controlledcommunications between devices on the network. This technology has been proven in field trials andreal plant installations across a broad range of process control industries.
Each device in the mesh network can serve as a router for messages from other devices. In other words,
a device doesn't have to communicate directly to a gateway, but just forward its message to the next
closest device. This extends the range of the network and provides redundant communication routes toincrease reliability.

The Network Manager determines the redundant routes based on latency, efficiency and reliability. To
ensure the redundant routes remain open and unobstructed, messages continuously alternate between
the redundant paths. Consequently, like the Internet, if a message is unable to reach its destination by
one path, it is automatically re-routed to follow a known-good, redundant path with no loss of data.
The mesh design also makes adding or moving devices easy. As long as a device is within range of othersin the network, it can communicate.
For flexibility to meet different application requirements, the WirelessHART standard supports multiple
messaging modes including one-way publishing of process and control values, spontaneous notification
by exception, ad-hoc request/response, and auto-segmented block transfers of large data sets. These24

capabilities allow communications to be tailored to application requirements thereby reducing powerusage and overhead.

COMPONENTS
Gateway provides the connection to the host network. WirelessHART and then the main host interfaces
such as Modbus – Profibus – Ethernet. The Gateway also provides the network manager and security
manager (these functions can also exist at the host level – but initially they will be in the gateway).
The Network Manager builds and maintains the MESH network. It identifies the best paths andmanages distribution of slot time access (WirelessHART divides each second into 10msec slots). Slot
access depends upon the required process value refresh rate and other access (alarm reporting –configuration changes).
The Security Manager manages and distributes security encryption keys. It also holds the list of
authorized devices to join the network.
The Process includes measuring devices – the HART-enabled instrumentation.
A Repeater is a device which routes WirelessHART messages but may have no process connection of its
own. Its main use would be to extend the range of a WirelessHART network or help “go around” anexisting or new obstacle (new process vessel). All instruments in a WirelessHART network have routing
capability which simplifies planning and implementation of a wireless network.
The Adapter is a device which plugs into or attaches to an existing HART-enabled instrument to pass the
instrument data through a WirelessHART network to the host. The adapter could be located anywhere
along the instrument 4-20mA cable; it could be battery powered or obtain its power from the 4-20Ma
cable. Some adapters will be battery powered and use the same battery to power the instrument as well
– in this case there will be no 4-20mA signal to the host – all process data will be reported via
WirelessHARTA Handheld Terminal may come in two versions.
1) The handheld will be a standard HART FSK configuration unit (just add new device DDs or DOF files)
just like the one used for everyday tasks such as routine maintenance and calibration checks. In the caseof wireless support, the handheld is used to join a new instrument to an existing WirelessHART network.
2) The handheld has a WirelessHART connection to the gateway and then down to an instrument andcould be used for reading PV or diagnostics.

GETTING STARTED
WirelessHART technology brings a new dimension to the world of process automation. Building on theproven success of the HART Protocol, WirelessHART extends the reach of process instrumentation in a
way that is compatible with existing systems and practices.

25

Let’s review the straight-forward steps needed to ensure a successful WirelessHART installation.
Planning a WirelessHART Project
1. Scope of Projecta. What are the objectives for the project – PV monitoring, non-critical control or
instrument condition monitoring. The answer to this question will affect the devices you
select - battery powered instruments or WirelessHART adapters, for example. As part ofthe scope, be sure to review: area of network coverage, density of the area and primaryand secondary instrumentation.
2. Planning the Network
a. There are several ways by which you can plan a network and allocate devices. They are
similar to those used when allocating instruments to I/O cards in a PLC/Controller
however there are some new considerations such as gateway placement and update
rates.
b. WirelessHART could have little impact here however there will be some things that arenew. For example, the instrument data sheet and I/O schedule will need to reflect new
information such as Network-ID – Join Key – Refresh Rate.
3. Host Integrationa. Here the emphasis is upon using existing protocols (Modbus – Profibus) for hostintegration and existing tools for instrument configuration. The new consideration issecurity – which is built-in!
Device Placement
Don’t forget this is a mesh network. Instruments do not need to be within the range of the gateway but
rather just need to be close to another wireless instrument.
Tips for Network Planning:
•
•
•
•
•

Locate instruments based upon segmentation criteria
Check coverage via scaled site drawings
Locate repeaters as required
Can the gateway can be moved into the plant (check for necessary certification)
Use directional or remote antenna if needed

Device Specification
WirelessHART devices are all basically the same when it comes to their wireless characteristics. The
device should be registered with the Foundation which is an indicator of a good wireless design andinteroperability with other suppliers’ products.
Verify the range of the antenna since some devices may offer antenna options that will alter the
distance assumptions.

26Factory Configuration - Decide if you want the network ID and join key entered by your supplier (ifoffered).
Commissioning and Checkout
Planning a WirelessHART network is a fairly simple process. Common sense rules provide the guidance
for a successful installation. Here are a few things to remember:
A HART handheld or PC tool will allow you to join instruments to the network. Overlapping networks
will have different network IDs.
1. Steps – the Gateway
a. Install and power Gatewayb. Install devices one by one
 Begin with closest to the gateway
2. Steps – the WirelessHART Device
a.
b.
c.
d.
e.

Install or activate the device’s power sourceEnter the Network ID
Enter the Network Join Key
Set the refresh (update) rate
Verify the device has joined the network
 At the device using a handheld or other tool
 At the gateway

3. Steps – Commissioning a WirelessHART device
 Verify Device Operation
1. Check device TAG
2. Check device engineering units
3. Check PV Update rate
4. Check battery voltage
 Verify Gateway
1. Check for minimum of 5 direct connections
2. Check for 25% of devices with direct connections in large networks with<10% add repeaters if necessary
Commissioning a WirelessHART network
After all devices have been commissioned, allow time for the network to optimize (>4 hours). Checkeach device for at least 3 neighbors and check path stability for 60% minimum. Increasing the elevationof the antenna can correct many situations. Add a repeater if necessary.
Security
Allowing Access to the Network through Key Management (including Network ID Key Management)
includes a global key for all devices, individual key for each device, Join Key – Fixed, Rotating or27

Assignment at the factory with order or on the bench. White Lists may include only “approved” devices
allowed or require an approval procedure.
Best Practices
•
•
•
•
•

Each field device has at least 3 neighbors. The 3rd neighbor will act as a backup if one of the two
primary paths is obstructed or unavailable
Devices (antenna) mounted >0.5m from any vertical surface
Devices mounted >1.5m off the ground
Gateway should have at least 5 neighbors
25% of the network devices should have a direction connection to the gateway in large
networks

28

BENEFITS OF HART COMMUNICATIONThe HART Protocol is a powerful communication technology used to exploit the full potential of digitalfield devices. Preserving the traditional 4-20mA signal, the HART Protocol extends system capabilities for
two-way digital communication with smart field instruments.
The HART Protocol offers the best solution for smart field device communications and has the widest
base of support of any field device protocol worldwide. More instruments are available with the HART
Protocol than any other digital communications technology. Almost any process application can beaddressed by one of the products offered by HART instrument suppliers.
Unlike other digital communication technologies, the HART Protocol provides a unique communication
solution that is backward compatible with the installed base of instrumentation in use today. This
backward compatibility ensures that investments in existing cabling and current control strategies willremain secure well into the future.
Benefits outlined in this section include:•••

Improved plant operations including cost savings
Operational flexibility
Instrumentation investment protection

29

IMPROVED PLANT OPERATIONSThe HART Protocol improves plant performance and increases efficiencies in:•••

Commissioning and installation
Plant operations
Maintenance

COST SAVINGS IN COMMISSIONING
HART-based field devices can be installed and commissioned in a fraction of the time required for a
traditional analog-only system or other field protocols. Operators who use HART digital communications
can easily identify a field device by its tag and verify that operational parameters are correct.
Configurations of similar devices can be copied to streamline the commissioning process. A loop
integrity check is readily accomplished by commanding the field transmitter to set the analog output toa preset value.

COST SAVINGS IN INSTALLATIONThe HART Protocol supports the networking of several devices on a single twisted wire pair. Thisconfiguration can provide significant savings in wiring, especially for applications such as tankmonitoring.
Multivariable devices reduce the number of instruments, wiring, spare parts, and terminations required.
A single device can provide multiple measurements eliminating the need for additional wires. Some
HART field instruments embed PID control, which eliminates the need for a separate controller, andresults in significant wiring and equipment cost savings.

DIGITAL COMMUNICATION
A digital instrument that uses a microprocessor provides many benefits. These benefits are found in all
smart devices regardless of the type of communication used. A digital device provides advantages suchas improved accuracy and stability. The HART Protocol enhances the capabilities of digital instruments
by providing communication access and networking (Table 2).
Benefits

HART Instruments

Digital Instruments

Accuracy and stability

Reliability

MultivariableComputations





30

Benefits

HART Instruments

Digital Instruments

Diagnostics

Multiple sensor inputs

Ease of commissioning

Tag ID

Remote configuration

Loop checks



Adjustable operational parameters

Access to historical dataMulti-drop networkingAccess by multiple host devices



Extended communication distances

Field-based control

Interoperability



Table 2 – Digital Instruments vs. HART Instruments

31

IMPROVED MEASUREMENT QUALITY
HART-communicating devices provide accurate information that helps improve the efficiency of plant
operations. During normal operation, device operational values can be easily monitored or modified
remotely. If uploaded to a software application, these data can be used to automate record keeping for
regulatory compliance (e.g., environmental, validation, ISO9000, and safety standards).
Numerous device parameters are available from HART-compatible instruments that can becommunicated to the control room and used for control, maintenance, and record keeping (Fig 6).

Figure 6 – Examples of Device Parameters Sent to Control Room

Some HART devices perform complex calculations, such as PID control algorithms or compensated flow
rate. Multivariable HART-capable instruments take measurements and perform calculations at thesource, which eliminates time bias and results in more accurate calculations than are possible when
performed in a centralized host.

The HART Protocol provides access to all information in multivariable devices.
In addition to the analog output (Primary Variable), the HART Protocol provides
access to all measurement data that can be used for verification or
calculation of plant mass and energy balances.

32

Some HART field devices store historical information in the form of trend logs and summary data. These
logs and statistical calculations (e.g., high and low values and averages) can be uploaded into a software
application for further processing or record keeping.

COST SAVINGS IN MAINTENANCE
The diagnostic capabilities of HART-communicating field devices can eliminate substantial costs by
reducing downtime. The HART Protocol communicates diagnostic information to the control room or
asset management system, which minimizes the time required to identify the source of any problem andto take corrective action. Trips into the field or hazardous areas are eliminated or reduced.
When a replacement device is put into service, HART communication allows the correct operationalparameters and settings to be uploaded quickly and accurately into the device from a central database.
Efficient and rapid uploading reduces the time that the device is out of service. Some software
applications provide a historical record of configuration and operational status for each instrument. This
information can be used for predictive, preventive and proactive maintenance.

33

OPERATIONAL FLEXIBILITYThe HART Protocol allows two masters (primary and secondary) to communicate with slave devices andprovide additional operational flexibility. A permanently connected host system can be usedsimultaneously, while a handheld terminal or PC controller is communicating with a field device (Fig 7).

Figure 7 - Communication with Two Masters

The HART Protocol ensures interoperability among devices through Universal Commands that enable
hosts to easily access and communicate the most common parameters used in field devices. The HARTEDDL (Enhanced Device Description Language) extends interoperability to include information that may
be specific to a particular device. EDDL enables a single handheld configurator or PC host application toconfigure and maintain HART-communicating devices from any manufacturer. The use of common tools
for products of different vendors minimizes the amount of equipment and training needed to maintain aplant.
Device and Host Interoperability is also insured by a rigorous device testing and registration program.
HART technology extends the capability of field devices beyond the single-variable limitations of 4-20mA
in hosts with HART capability.

34

INSTRUMENTATION INVESTMENT PROTECTION
Existing plants and processes have considerable investments in wiring, analog controllers, junction
boxes, barriers, marshalling panels, and analog or smart instrumentation. The people, procedures andequipment already exist for the support and maintenance of the installed equipment. HART field
instruments protect this investment by providing compatible products with enhanced digital
capabilities. These enhanced capabilities can be used incrementally.

The HART Communication Protocol enables you to retain your previous
investments in existing hardware and personnel

At the basic level, HART devices communicate with a handheld terminal for setup and maintenance. As
needs grow, more sophisticated on-line, PC-based systems can provide continuous monitoring of device
status and configuration parameters. Advanced installations also can use control systems with HART I/O
capability. The status information can be used directly by control schemes to trigger remedial actions
and allow on-line re-ranging based on operating conditions and direct reading of multivariable
instrument data.

COMPATIBILITY OF HART REVISIONSAs HART field devices are upgraded, new functions may be added. A basic premise of the HART Protocol
is that new HART instruments must behave in precisely the same manner as older versions wheninterfaced with an earlier revision host system. This backward compatibility protects your investment
for years to come.

35

GETTING THE MOST OUT OF HART SYSTEMS
To take full advantage of the benefits offered by the HART Communication Protocol, it is important thatyou install and implement the system correctly. The following section contains information that can help
you to get the most from your HART system:
•
•
•
•
•
•
•
•
•

Wiring and Installation
Intrinsic safety (IS)HART multi-drop networks
Control system interfaces
Multiplexers
Reading HART data into non-HART systems
Commissioning HART networks
Device status and diagnostics
Connecting a PC to a HART device or network

36

WIRING AND INSTALLATION
In general, the installation practice for HART-communicating devices is the same as for conventional 420mA instrumentation. Individually shielded twisted pair cable, either in single-pair or multi-pairvarieties, is the recommended wiring practice. Unshielded cables may be used for short distances if
ambient noise and cross-talk will not affect communication. The minimum conductor size is 0.51 mm
diameter (#24 AWG) for cable runs less than 1,524 m (5,000 ft.) and 0.81 mm diameter (#20 AWG) for
longer distances.

CABLE LENGTH
Most installations are well within the 3,000 meter (10,000 ft.) theoretical limit for HART communication.
However, the electrical characteristics of the cable (mostly capacitance) and the combination ofconnected devices can affect the maximum allowable cable length of a HART network. Table 3 showsthe effect of cable capacitance and the number of network devices on cable length. The table is basedon typical installations of HART devices in non-IS environments, i.e. no miscellaneous series impedance.
Detailed information for determining the maximum cable length for any HART network configuration
can be found in the HART Physical Layer Specifications.
Cable Capacitance – pf/ft (pf/m)
Cable Length – feet (meters)
No. Network
Devices
1

5

10

15

20 pf/ft

30 pf/ft

50 pf/ft

70 pf/ft(65 pf/m)(95 pf/m)(160 pf/m)(225 pf/m)

9,000 ft

6,500 ft

4,200 ft

3,200 ft

(2,769 m)(2,000 m)(1,292 m)(985 m)

8,000 ft

5,900 ft

3,700 ft

2,900 ft

(2,462 m)(1,815 m)(1,138 m)(892 m)7,000 ft

5,200 ft

3,300 ft

2,500 ft

(2,154 m)(1,600 m)(1,015 m)(769 m)6,000 ft

4,600 ft

2,900 ft

2,300 ft

(1,846 m)(1,415 m)(892 m)(708 m)Table 3 – Allowable cable lengths for 1.02 mm (#18 AWG) shield twisted pair37

INTRINSIC SAFETY
Intrinsic safety (IS) is a method of providing safe operation of electronic process-control instrumentationin hazardous areas. IS systems keep the available electrical energy in the system low enough that
ignition of the hazardous atmosphere cannot occur. No single field device or wiring is intrinsically safe byitself (except for battery-operated, self-contained devices), but is intrinsically safe only when employed
in a properly designed IS system.

INTRINSIC SAFETY DEVICES
HART-communicating devices work well in applications that require IS operation. IS devices (e.g.,barriers) are often used with traditional two-wire 4-20mA instruments to ensure an IS system inhazardous areas. With traditional analog instrumentation, energy to the field can be limited with orwithout a ground connection by installing one of the following IS devices:••

Shunt-diode (zener) barriers that use a high-quality safety ground connection to bypass
excess energy (Fig 8)
Isolators, which do not require a ground connection, that repeat the analog
measurement signal across an isolated interface in the safe-side load circuit (Fig 8a).

Both zener barriers and isolators can be used to ensure an IS system with HART-communicating devices,
but some additional issues must be considered when engineering the HART loop.

Figure 8 – 4-20mA Loop with Zener Barrier

Figure 8 a – 4-20mA Loop with Isolator
38

DESIGNING AN IS SYSTEM USING SHUNT-DIODE BARRIERS
Designing an IS direct-current loop simply requires ensuring that a field device has sufficient voltage tooperate, taking into account zener barrier resistance, the load resistor, and any cable resistance.
When designing an IS loop using shunt-diode barriers, two additional requirements must be considered:••

The power supply must be reduced by an additional 0.7 V to allow headroom for the
HART communication signal and yet not approach the zener barrier conduction voltage.
The load resistor must be at least 230 Ω (typically 250 Ω).

Depending on the lift-off voltage of the transmitter (typically 10–12 V), these two requirements can bedifficult to achieve. The loop must be designed to work up to 22mA (not just 20mA) to communicate
with a field device that is reporting failure by an upscale, over-range current. The series resistance forthe same zener barrier may be as high as 340 Ω. To calculate the available voltage needed to power atransmitter, use the following equation:•

Power Supply Voltage – (Zener Barrier Resistance + Sense Resistance) × Operating Current (mA)
= Available Voltage

Example: 26.0 V – (340 Ω + 250 Ω) × 22mA = 13.0 V
Any cable resistance can be added as a series resistance and will reduce the voltage even further. In
addition, the power supply to the zener barrier must also be set lower than the zener barrier conduction
voltage. For example, a 28 V, 300 Ω zener barrier would typically be used with a 26 V power supply.
While it is difficult to meet the two requirements noted above for a network using shunt-diode barriers,
it can be done. Following are two possible solutions to the problem:
1. Shunt the load resistor with a large inductor so that the load resistor impedance is still high (andmainly resistive) at HART signal frequencies, but much lower at direct current. This solution,
while it does work, is physically somewhat inconvenient.
2. Use an IS isolator rather than a shunt-diode barrier. The output voltage on the hazardous side isusually specified as greater than X Vdc at 20mA (typically 14-17 V). This value already includes
the voltage drop due to the internal safety resistor, so the only extra voltage drop is that due tocable resistance. System operation at 22mA requires reducing the 20mA voltage by 0.7 V (340 Ω
× 2mA).

DESIGNING AN IS SYSTEM USING ISOLATORSThe implementation of HART loops in an IS system with isolators requires more planning. An isolator isdesigned to recreate the 4-20mA signal from the field device in the safe-side load circuit. Most older
isolator designs will not carry the high frequencies of HART current signals across to the safe side, norwill they convey HART voltage signals from the safe side to the field. For this reason, HART

39

communication through the isolator is not possible with these older designs. (It is still possible to workwith a handheld communicator or a PC with an IS modem on the hazardous side of the isolator.) Whenretrofitting HART instruments into an existing installation, inspect the system for isolators that may haveto be replaced (any isolators that will not support HART signals).
Major suppliers of IS isolators have introduced designs that are fully HART compatible. Modern IS
isolators provide trouble-free design and operation and transparent communication in both directions.
IS device suppliers can assist with certification and performance specifications for their HARTcompatible products. Field device manufacturers will also supply certification details for their specificproducts.

MULTI-DROP IS NETWORKS
HART multi-drop networks are particularly suitable for intrinsically safe installations. With a multi-drop
configuration, fewer barriers or isolators are required. In addition, because each field device takes only
4mA (for a total of 16mA in a four-device loop) plain zener barriers can be used. With a 250 Ω load, 25 V
– (340 + 250 Ω × 16mA = 15.5 V, which is well above the transmitter lift-off voltage and leaves a margin
for cable resistance.

IS OUTPUT LOOPS
For output devices such as valve positioners, direct-current voltage considerations will vary dependingon the drive requirements of the device. Zener barriers may be possible. If not, modern HARTcompatible output isolators are appropriate.

IS CERTIFICATION CONSIDERATIONS
If the HART loop contains an IS-approved handheld communicator or modem, slight changes may beneeded to meet IS Installation Certification. Handheld communicators and modems add the HART signal
voltage to the voltage level coming from the zener barrier or isolator. For example, a handheld
communicator typically adds a maximum of 2V to the loop. Therefore, when used with a 28V zener
barrier, a total of 30V may theoretically be present in the loop. The allowable capacitance must be
reduced by about 15% to account for this increase in voltage.

IS NETWORK CABLE LENGTH CALCULATIONS
The cable length calculation must include the resistance of both the zener barrier and the load resistor.

40

SAFETY INTEGRITY LEVEL (SIL)
When performing a risk analysis on a process operation, each loop is analyzed for its potential
contribution to an unsafe condition should a failure occur. This assessment will define an acceptable
Safety Integrity Level (SIL) for each loop in that process. Using continuous HART Communication allows
the diagnosis of potentially dangerous failures and conditions to be significantly increased which
increases the SIL.
Every device in a loop has potential failure conditions. Sometimes increased maintenance will insure ahigher degree of reliability. For many devices, online diagnoses of failures or potentially dangerous
conditions are required to insure the level of reliability demanded by the SIL of the process.
It is up to the design team to select the proper products and procedures to demonstrate theachievement of the required SIL. Guidelines are offered in the ISA Standard SP84.01 and in the IEC
standard 61508 for methods to improve loop reliability.

41

HART MULTI-DROP NETWORKS
The HART Communication Protocol enables several instruments to be connected on the same pair ofwires in a multi-drop network configuration (Fig 9). The current through each field device is fixed at aminimum value (typically 4mA) sufficient for device operation. The analog loop current does not change
in relation to the process and thus does not reflect the primary variable. Communications in multi-drop
mode are entirely digital.

Figure 9 – Multi-drop Configuration

Standard HART commands are used to communicate with field instruments to determine process
variables or device parameter information (see HART Commands on page 19). The typical cycle timeneeded to read information on a single variable from a HART device is approximately 500 milliseconds(ms). For a network of 15 devices, a total of approximately 7.5 seconds is needed to scan and read theprimary variables from all devices. Reading information from multivariable instruments may take longer,
as the data field will typically contain values for four variables rather than just one.
The typical multi-drop network enables two-wire measurement devices to be connected in parallel.
Two-wire loop-powered and four-wire active-source devices can be connected in the same network. If
both two- and four-wire devices are used in the same network, three wires must be used to properly
connect the devices (see Water Treatment Facility Upgrade on page 157).

42

MULTI-DROP WITH HART FIELD CONTROLLERS
HART field controllers can also be wired in a multi-drop network (Fig 10). Each analog output signal fromthe transmitter/controllers is isolated from every other output signal, which provides a cost-effective
HART network configuration. In this case, the analog signals are not fixed and are used for the output
signal to the controlled device.

Figure 10 - HART Controllers with Multi-drop

43

APPLICATION CONSIDERATIONSConnecting HART field devices in a multi-drop network can provide significant installation savings. The
total cable length in a multi-drop network is typically less than the maximum cable length in point-topoint connections because the capacitance of the additional devices reduces the distance that the HART
signal can be carried (see Wiring and Installation section).
To save on installation costs, use HART multi-drop networks for remote monitoring stations, tank farms,
pipeline distribution systems, and other monitoring applications in which fast update rates are notrequired.

CONFIGURING DEVICES FOR MULTI-DROP OPERATION
Using the polling address structure of the HART Protocol, up to 15 devices can be connected in a multidrop network. The analog current of a HART device can be fixed by setting its polling address to anumber other than zero (0). With the HART Protocol, each field instrument should be configured withdifferent polling addresses or tag numbers before being connected to a multi-drop network—otherwise,
the master will not be able to establish communication with the slave devices.

44

CONTROL SYSTEM INTERFACES
When you change your existing control system by adding a HART interface, it is important to understandthe complete functionality offered by the HART interface. While several control system suppliers offer
HART interfaces, not all interfaces provide the same functionality.
Control systems such as a DCS (distributed control system), PLC (programmable logic controller), or
SCADA/RTU (remote terminal unit) implement only the functionality required for a given application. For
example, a flow control system may only read the primary variable of a device and provide no additional
support for viewing or changing configuration information. Other control system interfaces provide
comprehensive HART support, maintaining complete configuration records for all connected devices.
Contact your system supplier for specific details on their HART interface(s). Use the HART Host System
Capabilities Checklist (Appendix A) to obtain information from control system suppliers to identify
specific characteristics of their products.

HART I/O SUBSYSTEMS
Many HART-compatible I/O subsystems have multiple analog channels on each I/O card. Suppliers
choose whether to provide one HART interface per channel or to share one HART interface among
several channels. The number of shared channels per HART interface impacts the frequency of data
updates from a HART field device and the HART functionality that is supported.

HART I/O FOR MULTI-DROP SUPPORTFor the best performance and flexibility, one HART interface should be dedicated to each I/O channel.
Systems that share only one HART interface among several I/O channels may not support multi-drop
networks. The effective update rate of a multiplexed interface is slow enough that the performance ofmultiplexed multi-drop networks would not be practical. Some suppliers enable multi-drop support by
fixing the HART interface to one specific I/O channel. However, the other channels on that card may
then not be available for HART communication.

HART I/O FOR BURST MODE SUPPORT
Burst mode is an optional implementation in a field device. Receiving burst mode messages is optional
in a host as well. To take full advantage of burst mode, the I/O system should have one HART interface
for each channel. If the HART interface is shared by more than one channel, messages sent by the fielddevice may not be detected by the control system. If the system does not have the ability to configure
burst mode in the field device, a handheld terminal or other configuration tool is required.

45

DATA HANDLINGAll HART-compatible control systems can read the digital primary variable from a slave device. However,some system architectures may not be able to accommodate textual data (e.g., tag and descriptor
fields). In these cases, the controller is able to read the process variable, but may not have direct accessto all other data in the HART device.

PASS-THROUGH FEATURE
Some control systems are integrated with a configuration or instrument management application. In
these systems, the control system passes a HART command, issued by the management application, tothe field device via its I/O interface. When the control system receives the reply from the field device, it
sends the reply to the management application. This function is referred to as a pass-through feature of
the control system.

GATEWAYS
Gateways can be used to bring HART digital data into control systems that do not support HART-capable
I/O. Some systems support HART gateways with communication protocols such as Modbus, PROFIBUS
DP, or TCP/IP Ethernet. The typical HART gateway supports all Universal Commands and a subset of theCommon Practice Commands. Support varies depending on the gateway supplier. Some gateways
support access to Device Specific information.

SCADA/RTU SYSTEMS
RTUs used in SCADA systems use a special telemetry to communicate with the control system. RTUs
have the same considerations regarding multi-drop and burst mode support as other systems. However,
implementation is made more complex because RTUs often communicate to an upper-level host using acommunication protocol other than HART (e.g., Modbus). While there are many benefits toimplementing HART in an RTU (support of multi-drop, burst mode, and multivariable instruments), HART
data are only available to the central host system if the telemetry protocol supports the transfer of
HART commands or specific HART data (see Multi-drop for Tank Farm Monitoring – Page 60).

46

MULTIPLEXERS
HART-compatible multiplexers are ideal for users who want to interface with a large number of HART
devices. Multiplexers can be modular and are capable of supporting both point-to-point and all-digital(multi-drop) HART communication modes. Communication between a multiplexer and a host application
depends on the multiplexer capabilities (e.g., RS232C, RS485, Modbus, and TCP/IP Ethernet).
When installing HART multiplexer systems, the following capabilities should be considered:
•
•
•
•
•

Number of HART channels supported
Number of HART channels that share a HART modem
Burst mode support
Multi-drop support
Method of communication with the host computer or control system

MULTIPLEXERS – REMOTE I/O AS THE PRIMARY I/O SYSTEM
HART multiplexers can be used as the primary I/O front end for a HART-based control or monitoring
system (Fig 11). Typically, a PC acts as the host, providing the human-machine interface (HMI) andperforming other high-level functions. The multiplexer continuously monitors the field devices, reports
the current readings and instrument status to the host, and passes HART commands from the hostcomputer to the field devices.

Figure 11 – HART Multiplexer as the Primary I/O System

47

PARALLEL MONITORING WITH A MULTIPLEXER
When a traditional 4-20mA control system is using the analog signals for measurement and control
outputs, a HART multiplexer can be added to the network to gain access to the digital HART signal. Usinga multiplexer enables a supervisory computer to monitor diagnostics and device status, accessconfiguration information, and read any additional process inputs or calculations not provided by the 420mA signal.

Use a HART multiplexer to gain access to the digital HART signal

Two types of multiplexers are used in conjunction with a control system. A multiplexer wired in parallelwith the field wiring is commonly used when the control system wiring is already in place (Fig 12).

Figure 12 – HART Multiplexer with Existing I/O

A multiplexer can also be an integral part of the control system as a third-party I/O (Fig 13 ). As an I/O
system, the multiplexer can include IS barriers and other filtering capabilities and provide services to thefield device, such as galvanic isolation or power. For this type of installation, no additional terminations48

or space are required. The multiplexer can also act as a gateway to convert the HART messages toanother protocol such as Modbus, PROFIBUS, or Ethernet.

Figure 13 – HART Multiplexer Integrated with I/O

49

HART OVER PROFIBUS
HART field devices can be seamlessly integrated with PROFIBUS DP networks using the HART/DP Link,
which enables the connection of four HART devices and facilitates the pass-through of HART commands
to host applications on the DP network (Fig 14). The HART/DP Link supports IS installations.

Figure 14 – HART over PROFIBUS

50

READING HART DATA INTO NON-HART SYSTEMS
Many HART products are able to perform more than one measurement or output function (e.g., makemultiple process measurements, calculate process information, and provide positioner feedback
information). All of this information can be easily accessed digitally. However, existing controllers orinterface equipment may not have the ability to read digital HART data. Products are available that canread HART digital signals and convert them to analog (4-20mA) and alarm trip (contact closure)
information, which enables any traditional analog control system to take full advantage of the benefitsof HART-communicating devices.
The HART loop monitor continuously communicates with any HART-capable device and provides
multiple analog outputs (4-20mA) and multiple alarm trip (contact closure) outputs based on theinformation received (Fig 15). For example, smart HART multivariable mass flow transmitters sense
three process variables (pressure, temperature, and differential pressure or raw flow). Using these, they
perform an internal calculation to derive mass flow. The mass flow information is transmitted as a 420mA signal to the control system. However, there is no way to continuously monitor the non-primaryvariables used to make the calculation.
Installed transparently across the 4-20mA instrument loop, the HART loop monitor reads the HART
digital data that is continuously being transmitted on the smart transmitter’s analog loop wires, andconverts it to 4-20mA signals that can be readily accepted by a DCS (distributed control system) or PLC(programmable logic controller). This allows continuous tracking of a multivariable transmitter’s
second, third and fourth variables. HART loop monitors can also provide alarm trip (contact closure)
information to warn of high and/or low process conditions based on user-set trip points. Diagnostic
alarms can be set to warn of problems with a smart HART transmitter using the Field Device Status datathat is available in HART digital information.

51

Figure 15 – Monitoring Multivariable Transmitters

HART loop monitors also can extract data from smart HART valve positioners and damper operators (Fig16). Their 4-20mA analog outputs can be used to keep track of important parameters such as valve
stem position, actuator pressure or temperature. Alarm (relay) outputs can also be set to alert of asmart valve condition such as valve position (open/closed), low actuator pressure, and positioner
temperature (high/low).

52

For on-line testing of Emergency Shutdown valves, the HART loop monitor can be used to verify that thevalve is operational without the disruption of completely closing the valve (which is the traditional way
to verify ESD valve operation) by means of partial valve stroke testing.
For example, a Logic Solver (DCS or PLC) is used to apply a 90% (18.4mA) signal to the valve. When thevalve reaches the 90% set point, the relay in the HART loop monitor will trip to verify that the valve hasreached 90%. The test signal is then returned to 100% value by the Logic Solver, and the valve isreopened. A second HART loop monitor relay trip is set at 100% (full open) travel to ensure that thevalve did reopen completely after the test. This procedure verifies that the valve did reach 90%, provingthat the valve is not stuck. Because the valve was immediately reopened, the test has not impeded theprocess flow long enough to cause significant process disruption.
The HART loop monitor’s other analog outputs can be used to provide status information for otherimportant valve parameters such as valve travel and valve output pressure.

Figure 16 – Monitoring Partial Valve Stroke Testing53

COMMISSIONING HART NETWORKS
HART-based instruments have several features that significantly reduce the time required to fullycommission a HART network (loop). When less time is required for commissioning, substantial costsavings are achieved.

DEVICE VERIFICATION
Before installation, manufacturers usually enter device tags and other identification and configuration
data into each field instrument. After installation, the instrument identification (tag and descriptor) canbe verified in the control room using a configurator (handheld terminal or PC). Some field devices
provide information on their physical configuration (e.g., wetted materials)—these and otherconfiguration data can also be verified in the control room. The verification process can be important inconforming to governmental regulations and ISO quality requirements.
The commissioning process can be further streamlined by connecting a PC configurator to each HART
loop online, either by integration with the control system or by using one of the many available HART
multiplexing I/O systems (see Multiplexers). With this centralized approach, there is no need to movethe configuration device from one termination point to the next while commissioning all devices on the
network.

LOOP INTEGRITY CHECK
Once a field instrument has been identified and its configuration data confirmed, the analog loop
integrity can be checked using the loop test feature, which is supported by many HART devices. The loop
test feature enables the analog signal from a HART transmitter to be fixed at a specific value to verify
loop integrity and ensure proper connection to support devices such as indicators, recorders, and DCS
displays.
Use the HART Protocol loop test feature to check analog loop integrity andensure a proper physical connection among all network devices.

AS-INSTALLED RECORD KEEPINGA HART configurator also facilitates record keeping as installed device configuration data can be stored
in memory or on a disk for later archiving or printing.

54

DEVICE STATUS AND DIAGNOSTICS
Most HART field instruments provide both status information and diagnostic information. The HART
Protocol defines basic status information as information that is included with every message from a fielddevice. Basic status information enables the host application to immediately identify warning or error
conditions detected by the field device.
Status messages also enable the user to differentiate between measurements that are outside sensor or
range limits and actual hardware malfunctions. Examples of status messages are:
•
•
•
•
•
•
•
•

Field device malfunction
Configuration changed
Cold startMore status available
Analog output current fixed
Analog output saturated
Non-primary variable out of limits
Primary variable out of limits

HART instruments can implement extensive, device-specific diagnostics. The amount and type of
diagnostic information is determined by the manufacturer and varies with product and application.
Diagnostic information can be accessed using the HART Communication Protocol. Host applications
using DD files can interpret and display diagnostic information. Applications not using DD technology
may require product-specific software modules to interpret diagnostic information.
Many manufacturers offer special software applications for their own products. Some modules allow
users to customize for specific products. Manufacturers of valve actuators have made extensive use ofthis capability to provide preventative and predictive diagnostic information that greatly enhances thevalue of their products as compared to conventional actuators.
Several software applications are available that provide continuous communication with field devices
using a HART-compatible multiplexer and HART I/O (see Multiplexers). These applications provide realtime monitoring of status and diagnostic information.

55

CONNECTING A PC TO A HART DEVICE OR NETWORK
Personal Computers are commonly used for HART host applications for configuration and dataacquisition. A specially designed device (HART Modem) allows the HART network to be connected to theRS232C serial port or USB port of a PC (Fig 17).

Figure 17 – PC- based Device Configuration Using a HART Modem

56

INDUSTRY APPLICATIONS
Many companies in a wide variety of industries have realized the advantages of using the HART
Communication Protocol. In this section you can read real-world applications and the benefits thatcompanies around the world have realized through the application of HART technology. In addition to
three generic application examples (pages 60-62), information is provided from the followinginternational companies:
INDUSTRYCOMPANYLOCATION

Biopharmaceutical

Lonza

Switzerland

62

Bio-technologies

Genentech, Inc.

USA

65

ChemicalDupontUSA

70

Eastman Chemical Co.

USA

76

Monsanto

USA

78

Sasol Solvents

South Africa

84

Communications

ORBCOMM Global

USA

91

EnergyBP Canada Energy

Canada94

FoodFrench National Institute forAgronomic Research (INRA)
Cebrace

France99

Brazil102

Midwest Gas Company

USA

106

Pemex

Mexico109

PVDSA

Venezuela

112

Shell

Nigeria

115

Statoil

Norway118

Pharmaceutical

Clariant

Germany

125

Plastics

BP Cooper River

USA

129

Power & Energy

National Grid

USA

133

Glass
Oil
Gas

&

57

PAGE #INDUSTRYCOMPANYLOCATION

Ohio State University

USA

135

Appleton Paper

USA

140

Fraser Papers

Canada143

Vallviks Bruk

Sweden146

Steel

COSIPA

Brazil148

Water & Wastewater

AECOM

Canada151

Detroit Water & Sewerage
Department

USA

154

Milwaukee Metropolitan Sewerage
DistrictUSA

164

Saline Water Conversion Corporation

Saudi Arabia

166

Sluvad Water Treatment Works

Wales

169

Pulp & Paper

58

PAGE #

APPLICATION
HART MULTI-DROP NETWORK FOR TANK LEVEL AND INVENTORY MANAGEMENT
Accurate measurements for inventory management are essential in all industries. The HART
Communication Protocol enables companies to make sure inventory management is as efficient,accurate and low cost as possible.
Tank level and inventory management is an ideal application for a HART multi-drop network (Fig 18).
The HART network digital update rate of 2 PVs per second is sufficient for many tank-level applications.
A multi-drop network provides significant installation savings by reducing the amount of wiring from thefield to the control room as well as the number of I/O channels required. In addition, many inexpensive
process-monitoring applications are commercially available to further lower costs.

Figure 18 – Inventory Management with Multi-drop
One company uses a HART multiplexer to digitally scan field devices for level-measurement and status
information. The information is forwarded to the host application using the Modbus communication
standard. Multivariable instruments further reduce costs by providing multiple process measurements,
such as level and temperature, which reduces the wiring and number of process penetrations required.

59

APPLICATIONMULTI-DROP FOR TANK FARM MONITORING
In one tank farm application, 84 settlement tanks and filter beds on a very large site (over 300,000 m2)
are monitored using HART multi-drop networks and HART RTUs (see SCADA/RTU Systems). The HART
architecture required just 8 cable runs for 84 tanks, with 10-11 devices per run (Fig 19). Over 70
individual runs of over 500m each were eliminated. Cable savings were estimated at over $40,000 (USD)
when compared to a conventional installation. RTU I/O was also reduced, which resulted in additional
hardware and installation savings. The total installed cost was approximately 50% of a traditional 420mA installation.

Figure 19 – Tank Farm Monitoring with Multi-drop

60

APPLICATIONUNDERGROUND PETROLEUM STORAGE USING HART FOR ACCURACY
Underground salt caverns are frequently used for crude oil storage. One customer pumps oil frombarges into the storage caverns. An ultrasonic flowmeter records the total flow. To get the oil out of thecaverns, a brine solution is pumped into the cavern through a magnetic flowmeter. Brine and crude oil
flowing in both directions are measured and reported to the DCS using the HART Communication
Protocol for accuracy. The DCS tracks flow rate and total quantity to maintain a certain pressure inside
the caverns (Fig 20).

Figure 20 – Underground Petroleum Storage

61

LONZA CHOOSES HART TECHNOLOGY FORQUICK VALIDATION AND COMMISSIONINGPROJECT OBJECTIVES•

Assure quality data communications in processing specialty pharmaceuticalchemicals

and biotech

SOLUTION•

Used for both distributed control and asset management system applications•

A batch system exclusively using HART-enabled instrumentation across 1,700 I/O points•

Another DCS system hosts 1,400 HART devices with 7000 I/O points

RESULTS•

HART Communication reduces field device commissioning time by half; ‘pays for itself’ throughauto-generation of validation documentation•

HART technology supports continued adherence to current Good Manufacturing Practices

Lonza, headquartered in Basel, Switzerland, is one of the world's leading suppliers to thepharmaceutical, healthcare and life science industries. The chemical processor has a specialty in highquality biotech products, which are manufactured at its largest processing and research anddevelopment facility in Visp, Switzerland. Among its challenges, the site, with 2,600 employees, mustassure quality in the microbial fermentation of active, intermediate ingredients such as vitamin B3 or
niacin, of which Lonza supplies roughly 75 percent of the world’s demand.
Multi-product plants
To support current Good Manufacturing Practices (GMP) in its Small Scale Biotech Manufacturing facility(BPMSS) commissioned in 2004, Lonza chose HART technology for data communications between
process instrumentation and the distributed control system (DCS), including the plant’s first plant asset
management system. This system, integrated with its process control system, spans more than 1,700 I/O
for measuring temperature, pressure, flow, level and various analytical parameters.
HART Tech’s Speed, Validation Documentation Justifies Cost

62

The BPMSS employs 67, in two areas, microbial fermentation in one building and a purification process
housed in a new building. The facility, which uses solvents in fermentation and purification zones, isdesigned to hazardous-area standards.

Together with the DCS and asset management system, HART Communication “offers many advantages
in the BPMSS plant,” says Hermann Hutter, responsible for engineering and automation in the upstream
Lonza Exclusive Synthesis portion of the process.
Here, a 1,000-liter fermenter runs recipes in batch cycles that typically last five to eight days. HUTTER
says of HART technology’s benefits: “It speeds up the commissioning of the field devices; the device
commissioning time is halved.” Additionally, he says the asset management system “pays for itself
through the savings in the automatic creation of required validation documentation.”
HART technology is a standard off-the-shelf option from all the major instrumentation suppliers Lonza
uses; the company uses only HART technology-equipped field devices.
New, Larger Plant Also Uses HART Technology
Following success in its batch operations, Lonza chose HART technology as a solution in a new, larger
Biotech Pharmaceutical plant housing two 15,000-Liter fermentation units — that’s 30 times the
production capacity of the BPMSS facility.

63

The new facility employs an estimated staff of 150 and boasts a considerable process automation
network of more than 7000 I/O points and 1,400 HART-enabled field devices communicating across 55
DCS controllers, five servers, 30 operator stations and 60 human-machine interface stations.
Even as engineers were evaluating the extent to which it will use Foundation fieldbus, Hutter says, “wehave again decided for the HART technology, because the low risk of installing, which guarantees an intime plant start-up and offers a larger catalog of instruments.”

2005 HART Plant of the Year - FINALIST64

GENENTECH USES HART TO REDUCE LIFE CYCLE DEVICEMANAGEMENT, INSTALLATION AND START-UP COSTSPROJECT OBJECTIVES•Reduce installation costs and startup risks during construction of new biotechnology facility•

Manage critical device configurations that have a direct impact on plant efficiency and productquality•

Reduce lifecycle device management costs

SOLUTION•

Integrate HART Communication with distributed control system (DCS)•

Install HART-enabled instrumentation and products throughout facility

RESULTS•

Mitigated risks•

Eliminated addressing, network-sizing, special communication requirements•

No learning curve•

Enhanced view of instruments•

Remote device setup and configuration•

Online configuration-management database•

Regulatory compliance protection

Biotechnology manufacturer Genentech Inc. (San Francisco) is integrating HART Communication with the
distributed control system (DCS) in its CCP2 facility in Vacaville, California, to manage critical device
configurations that have a direct impact on plant efficiency and product quality. Genentech chose HART
technology because of its cost-effectiveness, availability, reliability, ease-of-use and flexibility.
“You can use HART to implement all the high-value functions of other bus technologies, but at a fractionof their cost, by using infrastructure that you probably already have in your plant today,” says Kevin
Kerls, a senior automation engineer in Genentech’s automation group. Kerls is helping automate the
Vacaville facility, which is currently under construction and is expected to produce 200,000 liters of
oncology pharmaceuticals by 2009.

65

Biotech’s Digital-Analog Future
Genentech is implementing HART technology with 15% of the I/O in the Vacaville facility. “There are a
lot of instrumentation manufacturers that offer HART-compatible products. That availability plus a huge
installed base makes HART a proven technology,” says Kerls.
“This is technology that’s going to continue to be supported and developed. It uses the same 4-20mA
wiring you’d use in traditional I/O, so there’s no steep learning curve.” He emphasizes this means
reduced installation costs and reduced risks during startup.
Kerls adds that the simultaneous analog and digital communication capability of the HART Protocol is a
key attribute. “We’re able to implement HART over simple 4-20mA twisted-pair signal cable, a provenand simple installation method,” he says. “There are no addressing schemes, network-sizing concerns,
or special communication requirements to deal with.”
And because the protocol uses standard signal cabling methods, there’s no learning curve for installers
either, he adds. “Since HART is so widely used already, there’s a very small learning curve formaintenance technicians.”

Genentech reports it also chose HART Communication because its installed instruments are HARTenabled. “So, we need no new infrastructure other than a new database server. The information isseamlessly integrated throughout the I/O, the DCS controller, and the process data server,” Kerls says. In
other systems, however, he believes multiplexers or other devices are needed to pick up digital signals.
“With our system, HART data is tightly integrated so that information is available right in the DCS.”

66

Kerls adds it’s important that Genentech can use any vendor’s flow or temperature devices as long as
they’re HART-compatible. “If a device that we wanted had a HART option, we asked for it. For almost all
devices, the HART capability was free from the vendor. But even if the HART option cost money, we stillpurchased it,” he recalls.
Remote Configuration Nearby
The ability to view instrument health and other monitoring parameters is available in Genentech’s DCS
without implementing added hardware.
“We’re able to view/modify instrument configurations without interrupting process monitoring,” Kerls
explains. Genentech chose HART Communication because other buses had design issues, which are
different from HART and its 4-20mA capability. “So it takes more time to get other buses operable. We
really felt that we get the majority of the benefit via HART,” he adds.
Number one on Kerls’ list of HART benefits is an enhanced view of the instruments. “This includes
status, alarming information, and remote configuration.”
Genentech also values the remote capabilities of HART technology. “The biggest bang for the buck isremote configuration and remote monitoring. HART won out over all the other buses,” Kerls asserts.
“Because HART provides remote capabilities, installation simplicity, and met our requirements, it easily
beat the other buses.”
Remote device setup and configuration is essential because it allows Genentech to easily backup
instrument configurations using a central database. The firm also can make changes to instrument
configurations from a controlled database compliant with 21 CFR Part 11—Title 21 Code of U.S. Federal
Regulations Part 11: Electronic Records; Electronic Signatures from the U.S. Food and Drug
Administration. Kerls says this was possible without relying on handheld devices or a technician’s
handwritten notes.
Overall Configuration Crucial
Central configuration management is another area where Genentech will use the HART protocol in their
new facility. The company will use a database to capture, view, verify, test, and backup instrument
configurations for more than 1,125 instruments during the startup of CCP2.
“The HART protocol with its online configuration-management database eliminates the need for a timeconsuming paper process,” says Kerls. “It probably saves an hour off each calibration which basically is ahalf a person-year saved under normal operations. In initial documentation of parameters and startup,
this may also save 3,000 hours. These are very conservative estimates.”Compared to traditional I/O, Genentech can use HART Communication to diagnose an instrument just by
opening a view, rather than sending someone out to the device’s location. “If anything goes wrong withthat device, it’ll notify the operator though a DCS alarm,” he adds.

67Genentech reports that HART-associated work at CCP2 is enabling more efficient management of
instrument configuration. “Once we get this up and running, part of corporate automation engineering’srole is to disseminate information about the project throughout the corporation,” says Kerls “This alsomeans educating our maintenance group on our systems’ capabilities and developing efficient processes
to leverage HART-enabled technology.”

Another benefit provided by HART technology at this facility includes building the corporation’s
instrument configuration-and-calibration Standard Operating Procedures (SOP) on how to use theprotocol and Genentech’s configuration management database.
“We’ll continue to minimize the time required to perform configurations and calibrations,” Kerls
emphasizes. “You can put these technologies in, but if you aren’t educating your lifecycle group—
maintenance and the local automation engineering group—to use them, then the corporation nevergets the full benefit.”
Benefits may be limited by not partnering with maintenance and local automation engineering on thefront and back ends of a project. “You may provide a solution based on incorrect assumptions and it
may not meet their business criteria,” says Kerls. “And, if you don’t partner with them on the back endof the project, the SOPs won’t be developed with HART technology in mind.”Compliance Protects Doses

68

Diagnostics. Maintenance. Regulatory compliance. SOPs exist for them. All are taken seriously at CCP2,
and HART technology plays a crucial role here, too.
“Our HART devices are installed as part of an 8,500-I/O DCS. Any device errors or alarms willautomatically be available to the operators/technicians,” explains Kerls. HART Communication allows
Genentech’s staff to receive device-specific alarm values, which reduces troubleshooting time. Fasterproblem identification goes directly to the bottom line.
In addition, the HART Protocol helps CCP2’s service department minimize the time required fortroubleshooting and calibrations. This is because all configuration parameters historically were noted byhand and often were misplaced, lost, or simply incorrect, Kerls adds. “Our HART implementation will
ensure that the current configuration is always correctly backed up.”
And, if an instrument needs replacement, HART also simplifies this process. “We simply need todownload the backed up configuration for the old instrument from our HART configuration
management database. These configuration parameters then upload to the new device directly throughthe analog I/O card without special connections,” says Kerls. “Being able to effectively manage our
instrument configurations reduces our regulatory risk and our risk to product.”
Risk to product involves reduced efficiency, which usually means producing less and producing poorer
quality. “If a critical instrument is involved and you can’t prove you had adequate control over properly
configured devices, it could lead to regulatory action and/or a recall of the entire batch,” says Kerls.
“More than likely, however, you’d have offline analytical measurements to monitor the batch so you
might not lose the batch, but you might spend a lot of time defending it.”Overall, Kerls is even more optimistic about the role of HART technology in Genentech’s future. “If HART
works well at CCP2, we can just roll it out to other Genentech plants,” he says. “If you use HART, you’regoing to save big time in lifecycle device management because the installation cost is no more than if we
installed traditional I/O systems.”

69

DUPONT USES HART DATA TO SATISFY SAFETY
INTERLOCK SYSTEM VALVE TEST REQUIREMENTS
PROJECT OBJECTIVES•

Needed a better way to test safety interlock control valves during plant operations.

SOLUTION•

DuPont added intermediate instrumentation to extract relevant data from the plant's HART
instruments, and Moore Industries' SPA HART loop monitor and alarm is used for this purpose•

Use partial valve-stroke testing of emergency shutdown valves during normal operations for
fewer and shorter shutdowns.

•

HART data is superimposed on the 4-20mA connection, and the SPA loop monitor and alarm
extracts the valve-stem position from the HART data. The SPA then sends the actual valve-stem
position data to the DCS via an additional 4-20mA connection.

•

Over 100 control valves equipped with Moore SPA loop monitors were installed, so valve safety
interlock testing would be a less labor-intensive and cumbersome operation

RESULTS•

Expedites testing of safety interlock valves, shortening plant shutdowns•

Provides fail-safe inputs to the hard-wired relay safety interlock system•

Allows remote configuration and ranging of virtually all instrumentation•

Reduces number / duration of shutdowns by using partial valve-stroke testing•

Establishes the foundation for an asset management system"Virtually all of the plant instrumentation is HART-enabled...temperature, pressure, level, and flow."
The DuPont DeLisle titanium dioxide manufacturing facility in Pass Christian, Mississippi, uses HART
Communication full-time in daily operations even though it does not have a HART-enabled control
system. The plant is migrating to using HART data for additional cost-effective solutions that will deliversignificant benefits to the enterprise today and into the future.

70

The DeLisle plant produces DuPont's proprietary
R-104 Ti-Pure titanium dioxide (TiO2). TiO2 is awhite pigment used in paint, plastics, andproducts where color retention is desired. TiO2
absorbs ultra-violet light energy and it also
possesses light-scattering properties thatenhance whiteness, brightness, and opacity.
TiO2 production requires a sophisticatedmanufacturing process that includes chemical
reduction, purification, precipitation, washing,and chlorination of titanium, iron, and othermetal sulfates.
"DuPont determined that the best way to control and monitor these processes was with HART-enabled
instrumentation," says Joe Moffett, project manager with DuPont. "Virtually all of the plant
instrumentation is HART-enabled, and this includes instruments used to monitor and control
temperature, pressure, level, and flow."
The DeLisle plant control and instrumentation system uses the HART Communication Protocol in avariety of ways. HART data is used as an input to the safety interlock system and as an input to thecontrol system. Like most other users, DeLisle personnel use handheld HART communicators forconfiguration, calibration, and troubleshooting. And as we'll see, future plans call for HART data as a key
input to an asset management system.
Normal plant operations are controlled by a Honeywell TDC-3000 distributed control system (DCS), andthe DCS is also used with a hard-wired relay system to control safety shutdown systems. Although future
generations of Honeywell DCSs will be able to directly receive and transmit HART data, the present DCS
does not have HART communications capability.
DuPont needed to add intermediate instrumentation to extract relevant data from the plant's HART
instruments, and Moore Industries' SPA HART loop monitor and alarm is used for this purpose.
One of the main reasons DuPont selected the SPA instrument is that Moore Industries submitted the
SPA to an independent third party for failure modes, affects and diagnostic analysis (FMEDA).

71

"FMEDA is a detailed circuit and performance evaluation that estimates the failure rates, failure modes,
and diagnostic capabilities of a device," explains Bud Adler, director of business development with
Moore Industries. "Using the reliability data from the SPA's FMEDA report, DuPont is able to verify that
required safety integrity levels (SILs) are attained."
HART Increases Uptime
TiO2 production involves many critical and potentially hazardous processes, so reliable operation of thesafety shutdown systems is of paramount concern. DuPont uses HART to provide key safety interlock
inputs to the DCS and to the hard-wired relay system.
The safety interlock system has a number of on/off control valves, each equipped with a HART-enabled
valve-stem positioner. Each control valve is connected to the DCS via a 4-20mA signal sent from the DCS
to control the valve position. HART data is superimposed on the 4-20mA connection, and the SPA loop
monitor and alarm extracts the valve-stem position from the HART data. The SPA then sends the actual
valve-stem position data to the DCS via an additional 4-20mA connection.

72

CRITICAL INTERLOCK DESIGN - OVERVIEW
SAFETY INTERLOCK SYSTEMREGULATORYSAFETYCONTROLLERCONTROLLERANALOG I/ O

ANALOG I/ O

STANDARDS

Dual Sensors
Dual FCE’s
VLV Position
Bad PVDual Diverse SIS’s

DISCRETE I/ O

RELAYSANALOG I/ O
HART BAD PV

SPA

HART VLV POSSPASC VLV TRIPSOL

RELAY VLV TRIP
SOL

INTERLOCK TRIP

13

The DCS compares the valve control output signal to the HART valve-stem position data to ensure
proper positioning. This data is used to verify correct functioning of the valve in normal operations, andto test the valve when DuPont performs periodically required plant shutdowns to verify operation of thesafety shutdown system.
The HART data allows DuPont to test valve safety interlock operation from the control room. Control
room operators place the appropriate DCS output in manual mode and adjust the 4-20mA control valve
output signal to open and close the valve. The SPA sends a 4-20mA signal derived from the HART databack to the DCS to verify valve position.
Consider the alternative: If the valve-stem position data was not available at the DCS through HART and
the SPA, DuPont would have to station an instrument technician at each valve to observe valve
operation. The technician would have to observe valve travel, and communicate this information tocontrol room personnel.
"There are over 100 control valves equipped with Moore SPA loop monitors, so valve safety interlock
testing would be a labor-intensive and cumbersome operation without HART Communication," observes
Moffett.

73

Online Tests Reduce Outages
DuPont has plans to take valve testing to another level-a level that will reduce the number and lengthsof outages required for safety interlock testing. Certain valve testing requirements for safety interlock
systems can be met with partial valve-stroke testing of emergency shutdown valves during normal
operations. Performing those tests during normal operations means fewer shutdowns are required, andthe required tests take less time so the shutdowns can be shorter.

Partial valve-stroke testing during normal operations is a procedure, either manual or automated, used
to stroke a valve over a small percentage of the valve's total travel range. For example, a safety interlock
valve might be fully closed during normal operations. Partial valve-stroke testing could be used to movethe valve to a slightly open position. This would verify valve operation without affecting normal
operations.
The present system could be used to undertake manual partial valve-stroke testing, or an upgradedsystem could be used to implement automated partial valve-stroke testing.

74

"We are currently evaluating device management system that would be able to directly accept datafrom all of our HART instruments," Moffett says, "and the system could be used to implement
automated partial valve-stroke testing."
Other plans call for using additional SPA capabilities to monitor the diagnostic status of the valve-stem
positioners, to provide alarm on low valve-operating air pressure, and to provide relay contacts for open
and closed valve position. For more critical applications, one-out-of-two (1oo2) and two-out-of-three(2oo3) configurations can be used to increase availability and reliability.
Fail-Safe System Relies on HART Communication
Most safety interlocking at the DeLisle plant is implemented through a dedicated DCS controller, but
certain processes must be equipped with a hard-wired relay safety shutdown system. Many of theseprocesses use HART-enabled pressure and temperature transmitters. Each of these transmitters sends a
4-20mA process variable signal to a Moore Industries SPA loop monitor that decodes the HART data
superimposed on the 4-20mA signal.
The SPA then sends a process variable signal derived from the HART data to the DCS, and it also sends
fail-safe alarm contacts to the hard-wired relay safety shutdown system. These alarm contacts are set toindicate high-level, low-level, and the presence or absence of the HART signal.
HART-enabled instruments allow DuPont to operate the plant in a safe and efficient manner. "HART and
the SPAs provide a solution that unlocks a wealth of diagnostic and process information in thepositioners and transmitters," says DuPont project manager Joe Moffett. "This information is used toincrease reliability and minimize the duration of required plant shutdowns."
DuPont is using this highly efficient TiO2 processing site as a benchmark for other facilities because of its
outstanding compliance with safety, health, and environmental requirements. DuPont plans to fully
exploit the available HART data with an asset management system that will provide automated partial
valve-stroke testing, predictive maintenance alerts, and comprehensive management of the plant
instrumentation system.
Major Benefits of HART Communication for DuPont
•
•
•
•
•

Expedites testing of safety interlock valves, shortening plant shutdowns
Provides fail-safe inputs to the hard-wired relay safety interlock system
Allows remote configuration and ranging of virtually all instrumentation
Reduces number / duration of shutdowns by using partial valve-stroke testing
Establishes the foundation for an asset management system

2002 HART Plant of the Year75

EASTMAN CHEMICAL USES HART PRESSURE TRANSMITTER TO
ACHIEVE COST-EFFECTIVE MAINTENANCE
PROJECT OBJECTIVES•

During process upsets, tank pressure exceeded range of analog pressure transmitters

SOLUTION•

Installation of a single HART-enabled transmitter, replacing two analog transmitters

RESULTS•

HART Communication lets the transmitter read actual voltage to determine actual pressure
without re-spanning the transmitter and introducing error•

Upsets that exceed expected range can be accurately measured by the digital HART
Communication signal.

•

Remote configuration saves time by reducing trips to the field

One HART-enabled transmitter replaces two analog transmitters to cope with pressure spikes and offer
more cost-effective maintenance

At Eastman Chemical Co.’s operation in Longview, Tex., pressurized tanks may have an allowable
working pressure of 63 psig, which may be 10 times more than the span of the tanks’ pressuretransmitters. According to Josh Lowery, electrical engineer at Eastman Chemical, pressure variations in
those tanks can cause problems.
On startup, one tank’s pressure shot up and popped a relief valve. “The tank shot up past 12 psig,” says
Lowery, who adds that the tank’s pressure transmitter span is 0-12 psig. A solution using HART
technology includes only one transmitter, rather than two as required before.
We use the HART signal to read the actual value at the cell, and so read the full range of thetransmitter,” says Lowery. This means operators can determine the actual pressure without re-spanning
the transmitter, which can increase transmitter error tenfold. “We can strip the HART signal, and get full76

range from transmitters in which the scale has decreased,” he says. “When we have upsets where theprocess went out of the expected range, we can capture the actual reading from the HART signal.”

Fewer instruments, a HART-enabled device, and improved diagnostics help Eastman Chemical save on
equipment cost and maintenance time.
In addition, HART technology’s remote configuration capability has helped improve operations at the
Texas facility. “HART saves us the time we used to spend going to and from the instrument,” Lowery
says. “More importantly, hazardous-area work requires many more permits. Hooking up with HART in
the control room is much easier.”
Remote configuration also allows Eastman to verify field wiring from the control room. Fewer
instruments, a HART-enabled device, and improved diagnostics means Eastman saves on equipment andmaintenance.

77

MONSANTO USES HART TO OPTIMIZE ASSETRELIABILITY AND IMPROVE PRODUCTIVITY

PROJECT OBJECTIVES•An engineer responsible for managing communication and control systems across two new
chemical plants with a combined 10,000 I/O points, sought a communication solution with theintelligence to predict failures•

Expand opportunities to take advantage of a new smart I/O infrastructure to incorporate datausing the HART Protocol.

•

Identify instrumentation issues before they impact production for better planning of scheduled,
predictive maintenance repairs.

SOLUTION•

Implemented Asset Criticality review and assigned ratings to more than 14,000 pieces ofequipment and instrumentation plant wide, including transmitters, control valves, and vapor
sensors.

•

Used the 700 installed HART-enabled devices and smart valve positioners to take advantage ofboth handheld and remote office-based systems.

•

Analyzed their data to quantify predictive versus reactive work by generating a “bad actor” listthat shows how much “cost avoidance” the reliability program is providing.

•Integrated intelligent HART device information with plant control, CMMS (SAP), asset
management and maintenance systems...and users.

RESULTS•

By getting connected to the information in their HART devices, improved instrument reliability
and reduced reactive maintenance costs•

Deployed predictive and condition-based techniques for early detection of instrumentation
issues (plugging, fouling, etc.) and prevented incidents costing $100,000 per hour of downtime.

•

Eliminated incidents of expedited products and environmental and safety problems that can
result when work is rushed during unplanned outages.

78•

Reduced the number of nuisance alarms and the ability to “turn off” tracking for somepreviously tracked data.

•

Identified “bad actor” devices through reliability efforts saving the plant $800,000 to $1.6
million per year in cost avoidance.

For the past few years, Monsanto’s Muscatine, Iowa, manufacturing facility has undergone atransformation in communication, in part through utilizing the capabilities of HART Communication inorder to enhance reliability data and help the plant achieve a new level of productivity. Using theintelligent device information significantly reduced costs and improved plant operations enabling thetransition from reactive to proactive and predictive maintenance.
The Muscatine facility spans 150 acres and employs more than 450 people to operate and manage eightprocess units running 24/7, year round, to produce agricultural chemical products including Roundup
herbicide and Acetanilide SelectChemistry products such as Harness
Xtra, Degree Xtra, and Warrant
herbicides. Starting in 1997, theinstallation of HART Communicationcompliant devices has helped enable
the plant to switch from batch tocontinuous
operationacrossprocessing units as well as in its Waste
Treatment and Utility process andFormulations and Packaging process.
Operating since 1961, the plant has
undergone various changes andexpansions, resulting in a variety of
automation systems. Ongoing efforts
have helped to integrate systems site wide, including an SAP computerized maintenance management
system (CMMS) and Emerson’s AMS asset management system.
This is a distributed platform that includes a central server, which hosts a master database andinterfaces with three DeltaV distributed control systems (DCSs) and four legacy Provox DCSs. Additional
applications are also installed including: ValveLink software to manage control valves, AlertTrack for
pushing critical device alerts to plant personnel; AMS Wireless for interfacing with a WirelessHART
Protocol-based network; and Connector software for pushing/pulling information between the database
and the calibration database. These systems and applications manage control networks site-wide.

79

In turn, control networks connect to more than 600 HART-enabled devices with more than 3,200
instrument assets total.
Setting asset priorities"Asset Prioritization is the foundation of all our Reliability Programs," says Joel Holmes, site reliability
engineer. That prioritization consists of continual evaluation and ranking of equipment according toseveral criteria that, in turn, determine the level of criticality for individual plant assets.
Initial efforts to prioritize assets included the reliability team’s 2006 discovery of a dramatic 30% error in
its SAP CMMS system, which lacked the ability to track reliability work such as labor and material costs
to the level of specific assets. In keeping with the plant’s Lean Sigma initiative, the plant reduced thaterror to below 5% by instituting order codes and deficiency notifications. This translated into more than
5,000 SAP records corrected.

By 2008, the plant’s use of predictive maintenance (PdM) included various conditioned-based
monitoring technologies--vibration, infrared thermography, motor analysis/testing, lubrication/greasing
and ultrasonic analysis. These paid-off in one case with the detection of early signs of plugging in two
mass flowmeters; back-flushing prevented up to six hours of downtime for a savings of $100,000 perhour.
“By implementing conditioned based monitoring techniques, we can effectively identify, diagnose,
troubleshoot, and ultimately repair issues prior to their effects negatively impacting production,”
Holmes says.

80

Hooking-up with HART technology
Since 2008, the plant has instituted a new level of reliability optimization to help prioritize, plan andschedule maintenance downtime for ongoing PdM, PM and control valve maintenance programs. This
began with the Asset Criticality reviews in which the reliability team assigned ratings to more than
14,000 pieces of equipment and instrumentation plant wide, including transmitters, control valves, andvapor sensors. Each asset was evaluated and assigned an A, B or C ranking, most critical devices getting
an “A” ranking, while others--such as run-to-fail assets or those with inline spares--being assigned a “C.”
The installation of the asset management system made it possible for the plant to use smart I/O
communication with digital fieldbuses as well as, for the first time, the digital portion of the HART
Communication signal. Today, the system encompasses approximately 700 HART-enabled devices andsmart valve positioners.
There are two phases to the program, representing two levels of use of HART Communication:••

Phase I employs evaluations in the field using a handheld communicator or mobile computer tocapture diagnostic data to an Excel-based file and, in turn, the CMMS, along with any deficiency
notifications. This allows technicians to effectively identify, plan, schedule, and kit the needed
parts and execute PM/PdM tasks.
Phase II takes fuller advantage of HART Protocol and compliant software (i.e., ValveLink forFisher and Trovis-View for Samson valve positioners) to remotely capture and compare
diagnostic test results with historical data to determine any instance of degraded performance.

From hand-held to WirelessHART
Before the asset management system was in place, HART Communication was not used at the plantother than for device configuration. Today, the protocol is used in the field as well as in the asset
management system, which Holmes says serves as “a smart handheld on steroids.”
Of course, it’s that and more. The asset management system supports a full, digital I/O infrastructure aswell as HART-enabled I/O, however, older legacy systems don't fully support this infrastructure. In suchcases, handheld communicators allow personnel to perform diagnostics and testing. Monsanto is
continuing to deploy HART technology in a way that will soon bring such data into seamless integration
with all-digital fieldbus data using WirelessHART technology. This allows standard-compliant modems or
adapters to send/receive data between HART-enabled devices and the control/automation system.
Where this has been deployed, data from devices communicating via WirelessHART and other protocols
are seamlessly integrated into the asset management system for a fuller presentation of diagnostic
information.
WirelessHART was first installed at the site's waste water facility. This was followed by a gateway81

adapter at one of the site's Acetanilide herbicide manufacturing units, which include wireless data on six
level instruments for pump seal pots. Five additional WirelessHART gateways have been purchased for
installation in the near future. Plans call for WirelessHART network coverage to extend across the entire
facility.
ROI paves way for plant wide expansion
As a result of the program’s demonstrated ROI, reliability programs have been steadily migrated acrossthe entire facility, providing increased availability, improved reliability, reduced downtime, and areduction in reactive work.
The benefits range from small improvements, such as a reduction in the number of nuisance alarms andthe turning off of previously required data flows to quantified dollar sums that are fueling expansion of
the project.

For instance, code analysis data in the asset management system helps to quantify predictive vs.
reactive work which in turn generates a Top Ten “Bad Actor” list with dollar figures on cost avoidance.
This helps quantify the level of cost avoidance the reliability programs have been providing...and hashelped leverage the program’s expansion plant-wide. Averages of 12 deficiency orders are entered eachmonth with a cost avoidance of over $1600 per work order. This correlates to more than $200,000 (USD)
annually since 2008.

82

“By increasing our focus on Asset Reliability, we’ve made a positive step change in key focus areas, notto mention ROI,” Holmes adds, calculating that since 2008, when the reliability program began, the plant
has achieved between $800,000 and $1.6 million in cost avoidance per year.
The key reason for these massive savings: connecting HART Communication and other protocol
instruments to the asset management system providing a direct dynamic tie to the health of theirinstruments. This, in turn, has helped eliminate instances of expedited products, worker stress andmistakes during outages and the environmental and safety problems that can ensue from technicalteams operating in a panic situation.
“HART-enabled devices (measurement devices and smart valve positioners) are at the core of thisachievement. Now management is asking the reliability group to identify what we want to do next.”
Holmes says.

2012 HART Plant of the Year83

SASOL SOLVENTS USES HART TO IMPROVEASSET MANAGEMENTPROJECT OBJECTIVES•An engineer responsible for managing communication and control systems across two new
chemical plants with a combined 10,000 I/O points, sought a communication solution with theintelligence to predict failures

SOLUTION•

Communication was implemented using the HART Protocol in field instruments and a DCS froma preferred vendor•

HART technology facilitated a consolidation of hardware and software vendors, and a program
to streamline and reduce maintenance-related alarms by 90%•

In one area of the site (acrylic acid and acrylates), 4,000 HART-enabled devices were used for aseamless diagnostic view for maintenance operations

RESULTS•The new system provides yearly savings estimated at a conservative 6.5 million South African
Rand, roughly $1 million at the time of implementation•

HART device-based diagnostic capabilities led to removal of 40 of 350 non-essential control
valves for savings of over a million•

Detection of faulty or poorly optimized valve positioners likewise led to savings estimated to top
two million Rand

The HART Protocol was a natural choice because it was compatible with Sasol Solvent’s existing
relationships and installed control system technology

84

Handed the task of overseeing the implementation of communication and control systems that would
serve as the automation data lifeline for two new plants, Sasol Solvents engineers started small, butfinished big. The plants, to be constructed by South Africa's Sasol Solvents and Olefins and Surfactants,
housed some 10,000 I/O points. A major installation of HART-capable intelligent devices led to big
savings by using HART technology already in the company's chemical plants.

Johan Claassen, engineering manager for control systems, instrumentation, and electrical, began with avision to implement a control system and corresponding field instrumentation that had the intelligenceto predict failures before downtime resulted. This initial vision ultimately led to estimated yearly savingsof 6.5 million South African Rand (US $1 million).
"We significantly exceeded my expectations. I was expecting two or three million Rand in savings," hesays. However, Claassen believes this figure to be conservative, as a number of benefits are hard or
impossible to quantify.
Claassen's and Sasol's results benchmark what's achievable, according to Ron Helson, Executive Directorof the HART Communication Foundation. "They really stepped out of the box and set the example forwhat is possible when you start using the full potential of smart instrumentation," he says.
To finish this big, however, Claassen faced numerous obstacles that had him battling balky technology
and overcoming objections from sometimes skeptical management.

85

Breaking new groundIn 2000, Claassen dusted off his crystal ball and peered into the future. He didn't do this because of the
new millennium. Rather, he went into the forecasting business because Sasol, an integrated oil-and-gas
company with substantial chemical interests, needed to expand.
In response to that need, Sasol would, over the next few years, build a butanol plant capable ofproducing 150,000 metric tons a year of solvent for the company's customers in the paint and ink
industries. The company would also construct an acrylic acid and acrylates project that would eventually
supply about 125,000 tons of products. Because of these projects, two plants would arise from empty
fields near the company's complex in Sasolburg, a town midway between Cape Town and Johannesburg,where Sasol had gotten its start 50 years earlier.
Claassen, who'd joined the company in 1995 with a control-system engineering degree from the
University of Pretoria, focused on the automation and control systems proposed for the new facilities.
He had his own plans for these systems, although he didn't have much of a team to help him push his
ideas.
"The team consisted of two people—myself and a Sasol technology engineer—with the vision to
implement a control system and field instrumentation that had the intelligence to predict failures before
they caused plant downtime," he recalls. The group started looking for solutions, investigating various
technology options. It also looked at different distributed control systems (DCS) to provide needed
functions.
But Claassen could not start from a blank slate. The automation and control systems for the new plants
had to take into account Sasol's existing relationships and installed technology. On that basis, HARTbased instruments and HART I/O had an advantage. Sasol already had a limited installation of HART
instruments and systems in other sites within Sasol's Solvents group. In addition, Claassen notes that thecommunications protocol offered another benefit.
"HART had the advantages of normal 4-20mA where you have one pair of wires per field device. Sasol's
design specifications for the new plants were built around this," he says.
Finding success
Changing to another industrial communication protocol would have forced the company to update
design specifications before building new facilities. But Claassen was prepared to go down that roadbecause he felt that new technologies had to be part of the new facilities.

86

Others weren’t quite as sure. The group’s proposal for a control system involving HART, Foundation
Fieldbus, and a new DCS was brought before Sasol’s board of directors in 2001, but that approach was
rejected. Disappointed, Claassen and his team continued planning. “We had to make the best of thesituation. Some of the board’s arguments made sense, and we had to honor it,” he says.
Several of those arguments involved timing and risk. The board approved a $200 million butanol projectin mid-2001 and fast tracked it for completion by the end of 2002. This approach, which involved taking
on two new technologies—one for the DCS and the other for the communication protocol—seemed too
difficult and presented too high a chance for failure.
Claassen’s team reworked their ideas, concentrating on implementing HART along with a DCS from avendor that Sasol had worked with before this project. When this idea was presented to the board,
Claassen got approval for the combination.
A wrinkle at the time was that this particular vendor offered no integrated HART I/O solution, meaningthat Sasol wouldn't be able to make use of the diagnostic capabilities of the technology. So the groupdecided to implement device management software from a rival vendor, using multiplexers to strip off
the diagnostic information from the field devices. This solution required the use of OPC forcommunication and the development of a diagnostic bit-extraction tool to handle traffic between the
hardware and software.
Disarming alarms
By the time the butanol plant was up and running in 2003, Claassen was hopeful that he had the desired
automation and communication solution in place. Over time, though, his optimism faded. Part of thecommunication set-up in the plant involved signals being sent to indicate the existence of diagnostic
errors in an instrument. An operator would then receive an alarm alerting him to the problem.

87

Unfortunately, operators and engineers were getting 10 alerts a minute, and many weren't about
anything an operator could affect. Consequently, those alarms were largely ignored.
Due to this alarm situation, the Sasol team switched its approach in 2004, implementing a solution thatused the same vendor for both hardware and software. The company also embarked on an alarm
management program and changed its philosophy on maintenance-related alarms, meaning that
operators were only presented with those alarms they could do something about. Claassen reports that,today, the number of alarms seen by operators has been cut by more than a factor of 10, and that's only
the beginning of the upgrades.
"As things improve, we will start training the operators to do first-line fault finding on our asset
management software as well," he says.
The change in alarm philosophy coincided with the completion of the acrylic acid and acrylates facility
and completion of current building projects. At present, Sasol uses some 4,000 HART instruments andabout 400 FOUNDATION fieldbus devices.

88

HART data is collected from intelligent instruments and conveyed to the process control system andasset management operator stations via HART flexible interface and via RS-485 from I/O to operator
stations.
The mix includes multiplexers, shutdown and control valves, and pressure and temperaturetransmitters. Claassen uses the intelligence and diagnostic capabilities in these instruments forpredictive maintenance strategies, root cause failure analysis, and fault tree analysis.
By using the diagnostic capabilities on the control valves, his group has determined which valves should
be removed, targeting 40 out of 350 at a savings of over a million Rand. They've also detected faulty or
poorly optimized valve positioners at a savings estimated to top two million Rand.
There are also advantages to the new systems that are harder to quantify. Claassen recalls that, after
installing the latest asset-management portal-software, the acrylic acid plant went through a scheduled
shutdown in September 2005. Using the asset management portal, Claassen and his team could give theproduction department an update on the health status of all field instrumentation and control valvesbefore restarting the plant.

89This was not possible before because it was not easy to tell how well quality-assurance and qualitycontrol tasks were done during the shutdown. Thanks to the new technology, Claassen was able toprovide an answer much quicker than before.
"In less than five minutes I could give my production department the go-ahead to start up the plant.
Before we had HART and the new software packages, it was very difficult to do this. You had to rely on
the information that your people could give you," he says.
Results obtained through the use of intelligent instruments have been so encouraging to this point that
Sasol plans to deploy similar systems in the company's other plants over the next few years.

2005 HART Plant of the Year90

ORBCOMM USES HART COMMUNICATION IN SATELLITESTO TRANSFER DATAPROJECT OBJECTIVES•

Find a low-cost communications solution for satellite transceivers sourced from multiple
manufacturers

SOLUTION•

HART technology equipped the full 28-satellite network for remote asset monitoring
applications•

Provide a method for customers to transmit critical data from offshore pipelines, remote wellheads, tanks or flowmeters

RESULTS•

Critical data easily, efficiently transmitted from the field to 500 miles ‘up,’ via Internet or filetransfer•

Rapid, fully-configurable data transfers and remote diagnostics for a wide variety of applicationsin the upstream oil and gas market

ORBCOMM Global, the first low-Earth orbit (LEO) satellite provider of data communications services,
helps its customers transmit wellhead pressures, natural gas production and tank levels

It’s official. HART Communication is “out of this world.” Since 1999, ORBCOMM Global has successfully
used the HART Protocol to transfer data from HART field devices to low-Earth orbit (LEO) satellites. Stillflying high today, ORBCOMM’s Controlsat FieldSentry RTU continues to support two-way message trafficwith HART-enabled field devices through the company’s satellite network.
“ORBCOMM Global became the first commercial LEO provider of data communications services when
we completed our 28-satellite constellation in September 1998” says Wally Walter, Controlsat productmanager. “The network was designed to be a low-cost communications solution with typical messaging
fees between 10 and 50 dollars a month (circa 1999) and affordable satellite transceivers available fromfive major manufacturers.”

91

HART Communication plays a pivotal role in ORBCOMM’s strategy for remote asset monitoring. With the
HART-based FieldSentry, rapid, fully-configurable data transfers and remote diagnostics are possible fora wide variety of applications. The FieldSentry is in service now providing remote diagnostics via satelliteof wellhead pressures, natural gas production and tank level monitoring for the upstream oil and gas
market.
Unlike expensive, high altitude Geostationary Earth Orbit (GEO) satellites, the new LEO satellite
technology places a constellation of small, inexpensive satellites in continuous motion at approximately
500 miles altitude. This reduced distance lowers the power requirements dramatically and greatly
simplifies the transmitter design.

92

“This system allows us to transmit critical data from offshore pipelines, remote well heads, tanks or
flowmeters to distant clients via Internet or file transfer,” Walter says.
In this “out of this world” application, the HART Protocol has proven itself once more to be a highly
capable, cost-saving process management tool. Many new HART-compatible products, like theFieldSentry, are making remote operations—data transfers, diagnostics, monitoring andmeasurements—easy and efficient.

93

BP CANADA ENERGY USES HART
COMMUNICATION TO IMPROVE PROCESS CONTROLAND SAVE MONEYPROJECT OBJECTIVES•

Achieve accuracy between 0.1 and 0.2 percent in custody transfer of oil as it changes ownershipen route to and from sites across Canada’s oil-rich Alberta province to meet contractual
requirements

SOLUTION•

In roughly a decade, a majority of the 600 transmitters were upgraded with HART devices andflow computers handling up to four transmitters each•

HART Communication provided an all-digital data path, eliminated the need for conversion
when analog-to-digital conversions were resulting in metering inaccuracies•

Transmitters were also upgraded for greater accuracy

RESULTS•

HART-enabled transmitters helped improve accuracy to save almost a quarter-million dollars
annually•

The plant achieved higher performance using upgraded transmitters and flow computers that
did not require analog step in obtaining measurements•

Marcel Boisvert, senior instrument/electrical craftsman, credits HART Communication with"fantastic" measurement balances and "phenomenal" accuracies•

Engineers and technicians saved time by reducing trips to the field94

Making use of the digital process variable output of HART-enabled transmitters, BP Canada Energy
improved its process control and saved substantial time and money.
Just as all roads once led to Rome, today all pipelines lead to Fort Saskatchewan – at least those carryinghydrocarbons in the middle of Canada’s oil-rich Alberta province. The pipeline hub is the BP Canada
plant located in the city. “We have just about every pipeline in central Alberta coming in and out of Ft.
Saskatchewan,” says Marcel Boisvert, a senior instrument/electrical craftsman with BP Canada Energy.

BP Canada Energy Plant - Fort Saskatchewan

The material in the pipelines not only moves through the area but also changes owners. BP Canada Ft.
Saskatchewan does the custody transfer measurement, and getting those readings right presents achallenge. However, thanks to hard work and HART Communication technology, Boisvert reports, "Ourmeasurement balances are fantastic. Our accuracies are just phenomenal.”
The plant’s engineering staff put the digital process variable output of HART-enabled transmitters touse, thereby improving accuracy, saving up to a quarter million dollars annually, and earning HART Plantof the Year honors for 2006. Theirs is a tale interest for anyone who wants to know how HART
technologies can help improve processes.

95

Balancing the Books
The Ft. Saskatchewan plant makes propane, butane, natural gas liquid (NGL) condensate and ethanewith carbon dioxide removed. In a given year, 1.5 million cubic meters of propane leaves the plant,
bound for other BP facilities. The other products produced also ship in large volumes. The plant staff
employs temperature and pressure readings to compensate the flow measurement and quantify what’s
in the pipes.
A decade ago BP Canada started installing HART-enabled temperature and pressure transmitters in Ft.
Saskatchewan. Today a majority of the 600 transmitters in the plant are HART-enabled. As part of the
upgrade package, the company also installed flow computers, up to four transmitters per computer.
In the initial configuration, Boisvert says the 4-20 mA analog signal output from a transmitter was fed
into a flow computer. The digital signal superimposed atop the analog signal as part of the HART
standard functioned as a second communication channel to and from the transmitter but was not being
used by the flow computer.
For audit and other purposes, flow-computer readings were and are compared to that of a standard,
certified gauge. One plant staff person handled transmitter calibration while another did the meter
proving. The accuracy in the mass delivery demanded by contract was one or two tenths of a percent, afigure that translated into a need for highly accurate temperature and pressure readings.
For example, a temperature error of 0.25 °C results in up to a 0.07% net flow error. Multiplied by theamount of product Ft. Saskatchewan ships, that error meant a potential loss of $250,000 a year. For
NGL, the corresponding figure was $350,000, creating strong incentives for accurate measurements. In
addition, those receiving the product would make their own readings and take action if a large enoughdifference was found. “There will be a correction, if you have somebody at the other end able to do themeasurement as well as you do or better,” says Boisvert in explaining what would happen.
Speaking one language
Problems, however, cropped up when Boisvert and coworkers tried to reduce the measurement error.
Despite diligent transmitter calibration efforts that should have kept the devices operating within atenth degree, meter proving continued to indicate an inaccuracy of up to half a degree. The employee
proving the meter would then adjust the transmitters or ask for them to be calibrated. Calibration
showed that the transmitters were working well within tolerances. The sequence would then repeat foreach employee's area until various team members witnessed each.
The team finally found the problem to be within the flow computer, specifically in the transformation of
the analog signal into its digital equivalent. “The analog to digital conversion was not as accurate as
what we were looking for,” notes Boisvert.

96

The errors weren’t great, perhaps 0.2 to 0.5 °C on a range of -18 to +65.5 °C. On the pressure side, thediscrepancy might be up to 50 kiloPascals on a range of 10,000 kPa. Those small errors, though, wereenough to eat up a significant part of the overall allowable error budget.
Faced with this problem, the team started looking for a solution. A series of tests convinced them thereadout at the transmitter agreed with analog and digital signals. That was when the group decided tosidestep conversion, notes Boisvert. “If the flow computer speaks HART and the transmitter speaks
HART, let's read the digital value rather than the analog value,” he says, thinking through the process.
The simple-sounding idea required a bit of work. For one thing, the flow computer's model didn’t
natively read or write HART commands. However, it was programmable at a low level. The vendor
provided what was essentially a translator, allowing Ft. Saskatchewan’s team to worry only about thehigher level application software.
Part of the solution also involved upgrading the transmitters. A typical specification for a transmitter of
0.5-degree accuracy wouldn’t work. “We were looking for that 0.2 degree accuracy,” says Boisvert.
Working with vendors, they found transmitters that would hit the more stringent spec. Such a tightening
only made sense, though, because the conversion-induced error had been eliminated.
Highly accurate results
With transmitters and flow computers talking without an analog step in the middle and with moreaccurate transmitters, the Ft. Saskatchewan plant achieved the desired performance. It’s hard to
pinpoint an exact dollar figure saved due to the improvement because, as Boisvert notes, the error could
have been positive or negative. The total amount of the possible adjustment, however, runs in the97

hundreds of thousands of dollars a year. Since the setup has been in place for a decade, potential
savings are in the millions of dollars.
Another benefit even harder to quantify has been removal of internal inconsistencies. That hascontributed to creation of a well- deserved reputation that helps in certifying measurements to external
parties. “There are never any issues about our accuracy,” says Boisvert.
There’s also been some savings of engineering and technician time. To take one example, the old meter
proving required one employee to take a reading from a certified device placed next to the transmitter.
The staffer would then have to go to where the flow computer was located and see what it measured.
Finally, the employee would have to travel back to the certified instrument and hope there hadn’t beena process change during this back and forth. Now the task is much easier because the transmitter's
digital display shows what the flow computer sees. “He can look at the certified device sitting right next
to the digital display on the transmitter and compare his readings,” notes Boisvert.
There are also time savings because instruments aren’t being tweaked, and other adjustments aren’t
being made only to be undone later. BP Canada Energy estimates total savings of at least an hour aweek of engineering and technician time.
As for lessons learned by the whole process, Boisvert cites one that could apply to a wide variety ofsituations. “HART is not just a maintenance tool. It is a process improvement tool as well,” he says.

2006 HART Plant of the Year98

INRA USES HART COMMUNICATION TO GAINING HIGHRESOLUTION PROCESS VALUESPROJECT OBJECTIVES•

Optimize the number of process variables that can be cost-effectively measured inline•

Obtain an accurate data feed for math modeling of multivariable parameters

SOLUTION•

In addition to direct data measurements, use HART-enabled multivariable transmitters for
proprietary math models used in real-time process optimization

RESULTS•

HART Communication-derived data leads to predictive process models, resists electrical noise•

Wiring and device maintenance require minimal investments•

Measurement quality is “superb, “accuracy is excellent“ and “the analog path in themeasurement chain is shorter” _ INRA reports

French agro-food researchers use HART technology to create a mathematical model with high resolution
real-time HART process values
Researchers at the National Institute for Agronomic Research (INRA) in Thiverval-Grignon, near Paris,
France, are using HART Communication for inline measurement of key parameters in microbiologic
processes as they occur during the production of yogurt, beer and wines. The French researchers arealso acquiring valuable data required for the calculation of fermentation rates inside tanks, determining
sugar and ethanol concentration, and obtaining indirect pH measurements during yogurt maturation
through mathematical models developed by INRA.
“We are a state research lab, but we market the information gained in our labs to industrial production
plants throughout Europe and worldwide,” says Bruno Perret of INRA’s Department of Food andFermentation Engineering. “We use pilot plants, where we experiment with fermentation processes.”
According to Perret physical parameters are difficult to measure because many of INRA’s biologicalprocess parameters require inline measurements that are physically challenging to achieve in a costeffective manner. In addition, it is hard to find a sensor that is reliable and inexpensive, as is the case in99

pH measurement during yogurt production or in measuring alcohol and sugar concentrations during
fermentation in breweries and wineries.
"Therefore, we have developed software packages with mathematical models that receive real-time
digital measurements from HART multivariable transmitters to calculate these values," Perret says.
Specifically, according to
Perret, process values fromthe multivariable transmitters
are filtered (mean value)
locally in the transmitters fora better stability of themeasurement, using the
HART transmitters integrated
output damping functions.
This is more efficient thenhaving filtering done by thehost software, and especiallyavoids bottlenecks in thedigital communication rate,
which is limited in a multidrop network. The result isbetter resolution and stabilityof measurements, which
would be much more difficult
toachievemakingevaluations based solely on
analog transmitter outputs.
"Our process control is much
more efficient with HART
Communication. In fact, ourmodel is so accurate that
simply changing a few
parameters makes it possible
to predict the process
evolution," Peret says. This last point is particularly important when the electrical environment of afactory is noisy.
INRA has two trademarked HART software packages with HART technology-derived master capabilities:
Oeno-Beer Control, which is used to manage ethanol concentration and density; and YAB, a specialized
in in-line pH estimation and trending routine used in yogurt production.

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"With HART, the wiring is simple and economical, and measurement point maintenance is easy. So,
operating costs are low," Perret says. "But the best thing is HART instruments have a superb
measurement quality. The accuracy is just excellent. Most importantly, with HART digital datatransmission, the analog path in the measurement chain is shorter."
INRA was founded in 1946 and became a national public scientific and technological establishment in1984 under the joint authority of the French Ministries of Research and Agriculture. Today INRA
operates 260 research centers, 80 experimental units and technological facilities and 100 service units.

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CEBRACE USES HART INTERFACE FOR ASSETMANAGEMENT INTEGRATIONPROJECT OBJECTIVES•

Improve plant maintenance by increasing volume and quality of data received from equipment•

Integrate data from HART-enabled devices in conjunction with data from a Foundation fieldbus(FF) network in a single plant asset management software system

SOLUTION•A HART-to-FF gateway brought data from both protocols together in a single plant asset
management software system•

An additional converter added full access to valve positioner variables for advanced diagnostics•

A profusion of cable types, lengths, impedances…

RESULTS•

Plant gained access to data from multiple protocols in an integrated, Web-enabled, asset
management application system•

Smart valve-positioning diagnostics further improved and loop operation and downtime
avoidance“The benefit for us was the ability to pull all our process information together, improve maintenancequality, and, most importantly, improve our mean time between failure,” the user reports
HART Communication proves a familiar, practical diagnostic solution that can coexist with Foundation
fieldbus networks – and integrate well in a single plant asset management software environment
As part of a major upgrade to their plant in Sao Paulo, Brazil, Cebrace Cristal Plano, a large plate andspecialty glass manufacturer, sought to improve overall plant maintenance quality by increasing thevolume and quality of data received from plant equipment.
Although a Foundation fieldbus (FF) network was already in place in the plant, Cebrace engineers choseto rely on instrumentation using HART Communication to enhance data retrieval in their maintenance102and diagnostic system. “Our plant technicians are more familiar with HART technology and feel more
comfortable relying on its proven capabilities in critical situations,” says Benedito Adalberto Pestana,
Cebrace Automation Systems Coordinator.
Using an off-the-shelf gateway between the HART and FF protocols, operators were able to view andcontrol instruments on both networks from the same plant asset management software system. The
software allowed the user to apply several tests via HART, such as partial/complete stroke, valve
signature, step response, mileage/stroke/reversal tracking, and input/output pressure checks. All thesefeatures allow analysis, alarm/warning generation preventing problems by identifying them before theyoccur.
“The benefits for us were the ability to pull all our process information together, to improve
maintenance quality and, most importantly, improve our mean time between failures,” says Pestana.

DESIGNED SOLUTION
Because of the advanced diagnostics demanded by this project, achieving a complete HART-to-FF
technology conversion, comprising Universal, Common Practice and Specific commands, required
accessing all the valve positioner variables. To do this, Cebrace engineers selected a HART-to-FF
converter since an analog signal is not required when the control strategy is being performed via a third
party programmable controller (see diagram).
Since there were a small number of positioners in the system, Cebrace engineers placed all ten
converters into a single battery of backplanes inside the control room instead of distributing them in thefield. One cell was also installed next to the converter sets and interconnected to the network via a fiber
optic cable with one FO/ETH converter at both ends.

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The proposed architecture to address the problem

A derivation was taken from every cable to connect each positioner to the converter’s eight HART
master ports. Even with such a wide variety of cable types, lengths and impedances, no operational
problems were detected after the installation was completed.

The installation scheme of each positioner

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ASSET MANAGEMENT“Our manufacturing facility is built around a huge linear machine hundreds of meters long. Any
disturbance, especially in the initial stages of the production process, can cause a major shutdown and,even worse, destroy the main oven,” Pestana adds.
“If this occurs, set up and restart lasts a minimum of 60 hours, which represents a cost of about$30,000US in lost product. Through the use of HART technology, we are able to maintain online
preventive maintenance full time and reduce maintenance costs at least 50 percent.”
HART integration allows Cebrace to monitor process-related variables, diagnostic status, andinformation stored in their database, such previous operation conditions, next scheduled shutdown formaintenance, etc., 24 hours a day, seven days a week. They are able to access all field devices fromevery station plant-wide and even worldwide (if an Internet connection is available) in a single, webbased, integrated software environment to improve loop operation and to avoid unscheduled
downtime.
CONCLUSION
The main benefit of this integration project was that the plant gained access to data from all fieldbus aswell as HART-enabled devices, in a single, integrated asset management application, at every station in
the plant as well as remotely using a secure Internet connection.
The high level of diagnostic data available via the HART smart valve positioner additionally allowed
access to information needed to improve loop operation and to avoid unscheduled downtime.

2003 HART Plant of the Year - FINALIST105

GAS PIPELINE COMPANY USES HART TO MODERNIZEOPERATIONS AND SAVE $1.25 MILLION ANNUALLY
PROJECT OBJECTIVES•

Replace paper chart recorders with cost-effective digital communications•

Extend automated meter-reading to a wireless network with an 80-mile radius.

•

Extend the HART Communication network beyond the traditional 10,000-foot (3,000-meter)
distance limitation.

SOLUTION•

Installed HART-enabled network gateway/multiplexer for use with a multivariable flowtransmitter providing flow measurement and data logging•

Spread spectrum radios provided the wireless link, with multipoint and repeater configurations,
between the network gateway and the HART-enabled instruments

RESULTS•

Reliable data acquisition from devices within a radius of up to 80 miles to a central host in Tulsa,
Oklahoma•

Data easily integrated with the pre-existing measurement system.

•

Eliminating manual paper-based operations saves an annual $1.25 million•

Additional savings include elimination of costly cable runs and hardware savings of almost 30%
on future instrumentation installations

When a major Midwestern gas pipeline company sought to modernize its legacy paper-based meterreading operations, HART technology proved equal to the challenge by providing a capable, flexible andcost-saving solution.
In an extraordinary automation project involving multiple “wireless” messaging links, the power andadaptability of the HART Communication helped a major Midwestern gas pipeline company meet thechallenge of modernizing its analog meter-reading infrastructure. HART technology provided thecommunication tool needed to create an extended meter reading network via spread spectrum radio
and satellite communication.

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The gas pipeline company planned to replace paper chart recorders on their natural gas pipeline with anautomated meter reading (AMR) system. The AMR system would have to be capable of acquiring datafrom devices within a radius of up to 80 miles, publishing field data from locations throughout theMidwest to a central host in Tulsa, Oklahoma, and integrating the data with an existing measurement
system.
To meet the challenge, company engineers chose the Director, a HART-enabled network
gateway/multiplexer from Arcom Control Systems used in conjunction with a multivariable flowtransmitter providing flow measurement and data logging capabilities.
“The HART master satisfied all the requirements for the project,” says John Tandy of Arcom Control
Systems. “The Director uses HART to acquire real-time and historical information. Data is then published
to a central host via satellite or over Ethernet via TCP/IP.”The AMR system uses spread spectrum radio and satellite communication to extend the HART network
beyond the traditional 10,000-foot (3,000-meter) distance limitation. Spread spectrum provides thewireless link between the Director and the HART instruments.
Tandy adds that the radios “allow great flexibility in network architecture through multipoint andrepeater configurations, as well as providing reliable data transmission of the HART messages,” Tandy

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adds. “With the use of repeaters, HART units can be brought into a single multiplexer from a radius of 80
miles or more.”
At each remote site the Freewave radio connects to the field devices using a serial HART interface. Thistransmits the HART signal from the radio onto the local current loop to a single or multi-dropped HART
network. Because up to 32 devices per radio network were required, the HART “poll by tag” feature was
implemented to allow more than the traditional 15 devices.
By implementing the HART-based AMR system, the pipeline company was able to realize cost savings inseveral ways. The paper chart recorders previously had to be collected and tabulated manually for eachmonthly billing. Now this is done automatically with ongoing savings estimated at $1.25 million per year.
Because the HART signal is transferred over the radio link, there is no need for a separate Remote
Terminal Unit (RTU) or multiplexer at each meter site. One Director is master to 32 HART meters,
allowing data consolidation.
Wireless communication avoids very costly cable runs to each HART meter. The multivariable flowtransmitter effectively combines a traditional flow meter and three discrete instruments into a single
instrument, yielding hardware cost savings of almost 30% per site. TCP/IP communication allows remotediagnostics and configuration, reducing the need for on-site technical support.
Global industry growth continues to present an ever-increasing challenge to provide strong networking
and interoperability communications solutions. HART technology has demonstrated for more than adecade that it is capable of meeting the challenge.

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HART-TO-ETHERNET GATEWAY: TWO DIVERSEAPPLICATIONS, ONE SOLUTION
What does a large refinery have in common with a 650 year-old wheat mill? A common HART Protocol
and a simple solution to a sometimes complicated problem in the HART-to-Ethernet gateway.
Numerous automation suppliers offer off-the-shelf gateways to bridge the data divide between the
HART protocol and many industrial Ethernet protocols. These gateways provide a highly effective meansof bring data from HART devices in the field and any host computer or device on the Ethernet network.
Consider these two very different plant environments…

REFINERY – MEXICOPROJECT OBJECTIVES•In Mexico, a PEMEX refinery required a means of integrating of all HART-compatible fielddevices into one user program.

SOLUTION•

Installed autonomous 100Mbit Ethernet Network (HART-LAN), ring topology with optical
Ethernet ports, conversion from RS485 using COM servers and HART LANs to accesses devices

RESULTS•

Each satellite room got a COM server; RS485 bus line extended as a two-wire cable as a bus line
connecting to HART multiplexer; HART Server automation interface allows user monitoring.

•

PEMEX refinery uses HART-to-Ethernet Gateway Web Server to integrate 10,230 analog inputs
and 2,430 analog outputs to satellite rooms up to 3 kilometers away

Faced with a daunting integration task, the PEMEX refinery in Madero, Mexico, turned to HART
Communication for a viable solution. A part of the overall requirement of the project was the full
integration of all HART-enabled field devices for parameter assignment and configuration into one user
program.

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Access to these field devices had to be via both a central computer with a back-up system andindividually using a Notebook in each individual satellite room. This involved the transfer of a total of
10,230 analog inputs and 2,430 analog outputs via 728 HART multiplexers (211 masters, 517 slaves).
Distance to the individual satellite rooms was up to 3km.
In order to effect the required functionality, engineers decided in favor of an autonomous 100Mbit
Ethernet Network (HART-LAN). A ring structure topology was selected with automatic redundancy
switchover. The ring structure was achieved by interconnecting the optical ports of the Ethernet
switches in the CCR bunker.
Successful conversion from Ethernet to RS485 interfaces in the satellite rooms has been achieved
through the use of COM servers. These devices are set to a specific IP address and can be addressed
through the corresponding device driver via Ethernet as an outlying RS485 interface. Thus, every stationon the HART LAN has access to these devices, which proved to be an excellent solution for individual
access via the Notebooks.
One COM server has been installed per satellite room and the RS485 bus line has been extended as a
two-wire cable. Up to 15 HART multiplexer masters are connected to this bus line. The centralcomputers and the Notebooks are equipped with seven software packages, including the HART Server
automation interface.

110

WHEAT MILL – GERMANY
PROJECT OBJECTIVES•

Ancient German wheat mill needed to transfer radar level-sensor data from silos to the control
room

SOLUTION•

HART-to-Ethernet Gateway acts as a Web server, sending data via wireless LAN to control room

RESULTS•

Process variables displayed in standard Web browser; no new cabling needed to bring data tocontrol room.

•

In Germany, the H. Thylmann Kilianstädtermühle wheat mill needed to transfer radar levelsensor data from silos to the control room.

A 650-year-old wheat mill near Frankfurt, Germany, is now linked with 21st Century process automation
thanks to the power of HART Communication used to send data from silos to the mill’s control room via
a standard Web browser.
The H. Thylmann stores bran in six silo tanks of 40- to 60-tons capacities. The mill equipped the silos
with guided radar level sensors that monitor tank levels. A HART-enabled multiplexer scans and collects
the analog and digital data from the level transmitters.
The data is fed to a HART-to-Ethernet gateway which acts as a web server. The data is then transmitted
via a wireless LAN to the control room located about 40 meters away and displayed as process values byusing a standard Web browser.
“There was no new cabling to the control room needed,” says Thomas Funfgeld, the mill’s
instrumentation manufacturer representative. “All equipment could be mounted in a single cabinet near
the silo tanks. Also, the HART data is available via the network to all users in the company.”
Visualizing the data with a standard Web browser saves additional money because custom display
software is not required. This is another example of how HART Communication, when used in a realtime process application, can provide simple, cost-effective solutions that can reduce operating costs
and improve process operations.

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PDVSA USES HART TECHNOLOGY TO
STREAMLINE PREVENTIVE MAINTENANCE PROCESSPROJECT OBJECTIVES•

Achieve trouble-free plant startup of a 248,000 barrel/day oil processing facility•

Eliminate erratic performance of under-performing field devices in a DCS network of 5,000
instruments

SOLUTION•

Addition of asset-managing software system platform to its DCS•

Use the combined platform's HART technology to access intelligent device diagnostic
information and root-out "bad actor" devices to be eliminated and/or replaced

RESULTS•Streamlined work processes led to reduced maintenance costs for a 60% reduction in lost profit
opportunities valued at $70 million in two years•

Instrumentation performance and calibration problems were prevented before startup. Numberof failures attributed to instrumentation during startup? Zero•

Since startup, HART technology has streamlined preventive maintenance, allowing this large
plant to operate with a staff of only five reliability engineers and 12 instrument technicians

One of Venezuela’s major producing oil fields lies in its Orinoco River basin; however, crude from this field isextra heavy and must undergo upgrading in one of several plants before refining. One of those plants isusing HART Communication to streamline operations and their preventive maintenance process.
The Petropiar Mejorador (upgrader) facility in the José Antonio Anzoátegui industrial complex nearBarcelona, Anzoátegui, Venezuela, is controlled by PDVSA (the Venezuelan national oil company) in ajoint venture with Chevron. It begins with the tar-like feedstock at 7.5 °API, and turns it into 26 °API
synthetic crude. The plant first started operation in 2003 as Petrolera Ameriven, and began delivering
product in January, 2004. By the middle of that year, it achieved normal production, with capacity rated at
248,000 barrels per day with 1,500 employees.

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As in any oil processing facility, reliability isparamount, and with 5,000 instruments communicating with the DCS, eliminating problems fromerratic devices was key. To achieve that,
Petropiar added an Asset Management System
platform to its DCS. This system uses HART
technology to communicate intelligent device
diagnostic information from instruments andactuators throughout the plant.

“Since our plant went on line in 2004, HART technology has opened a door of opportunity to thereliability community,” says Mariela Leon, Petropiar instrumentation reliability leader. “We were able tooptimize our work process creating a reduction of maintenance costs which led to a 60% reduction oflost profit opportunities (LPO) caused by instrumentation faults. Eliminating bad actors and having theability to reduce random failure has resulted in a reported reduction of LPO on the order of $70 million
in two years.”Petropiar’s maintenance group found that their efforts using HART technology made the plant startup
go much smoother, as instrumentation performance and calibration problems had been sought out andcorrected before it went on line. As a result, there were no failures attributed to instrumentation113

reported during the startup period. Their bad actors had already been identified and corrected,
eliminating 95% of related problems.
Since startup, this preventive method has continued. Calibration tasks are thoroughly defined, withroutes and schedules laid out for the entire universe of instrumentation. This emphasis on predictive
maintenance allows them to attend to only the items that really need attention, resulting in a 10%
increase in effective personnel “wrench time.” This has allowed the plant to operate with a staff of only
five reliability engineers and 12 instrument technicians and still stay ahead of most problems.
These experiences have caused the reliability team to look for other opportunities where HART has notalready been put to work. There is still a small population of installed devices that are not HART
capable, but these will be upgraded. All new instruments and process analyzers must be HART
compliant.
Moreover, all systems have not yet been integrated into the AMS, but this is also underway. Some partsof the safety instrumented system (SIS), some PLC driven subsystems, and the fire and gas (F&G) detection
system are still being incorporated into the larger asset management network.
One example of this increased reliability relates to valve positioners. “HART technology was used to
pinpoint a bad valve positioner which provided the justification to change or add positioners to 400
valves,” says Livia Lefebre, reliability superintendent. “We also demonstrated the partial valve stroke
application to management who then approved its use, significantly increasing the time between
required shutdowns.”
HART technology is also used at the oil production site that feeds Petropiar, and by the end of 2008 thetwo systems will be interconnected. This will allow the reliability engineers at the upgrader to analyze
what’s happening upstream as well.

2008 HART Plant of the Year

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SHELL USES HART COMMUNICATION TO IMPROVE NIGERIANPLANT OPERATIONSPROJECT OBJECTIVES:•

Improve on plant operation to increase throughput•

Improve maintenance efficiency

SOLUTION:•

HART devices and communications installed across the plant’s field instrumentation and control
networks for real-time process monitoring•

Use of remote HART communications for maintenance activities

RESULTS:•

Remote access to hard-to-reach places reduces the time and cost of trips to field devices•

Shortens time for instrument installation and configuration in half…or better•

Improves plant operations and maintenance through greater data visibility

HART Communication has sped instrument installations as well as maintenance jobs for Shell Petroleum
Development Company Nigeria, for improvements to operations and maintenance in the Soku Gas Plant
located in Port Harcourt, Rivers State, Nigeria.
Shell Petroleum Development Company Nigeria, needed to “improve on plant operation andmaintenance and to increase throughput,” says Awe Kayode, leader of the effort to bring HART benefits
to the company’s Soku Gas Plant.

115

The Solution
Devices equipped with HART communications were installed across the plant’s field instrumentation andcontrol networks for real-time process monitoring. Additionally, HART communication is used forpreventive maintenance and first-line maintenance jobs.

HART Communication made it easier to access the instrumentation in hard-to-reach areas such as theplant’s glycol regeneration skids where technicians would otherwise climb ladders. Kayode explains thatthe HART capability has helped the maintenance staff comply with its goals, which has had a “direct
impact in keeping our plant running.”
Benefits and Outcomes
The use of HART technology “has greatly reduced set-up and configuration time of field devices,”
Kayode says, citing the installation of new transmitters at the Soku plant’s Enhanced Gas Gathering
System: “The configuration time was initially scheduled for seven days, but was completed in threedays.”
Additionally, remote communications access has “greatly reduced” trips to the field. Instead of climbing
ladders to access instruments on a glycol regeneration skid, HART technology speeds access while
reducing time, cost and risk.

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Kayode adds that plant work processes and operations have been “greatly improved” through the betterdata visibility the HART Protocol provides, which he sums up as “knowing the status of field devices andbe able to be proactive in their maintenance.”

117

STATOIL USES HART COMMUNICATION TO
DELIVER NATURAL GAS FROM UNDER THE SEA
PROJECT OBJECTIVES•

Optimize efficiency in communicating data from an undersea gas field of 24 wells to a 1,200 kmlong undersea pipeline—the longest ever built•

Minimize the staff required to effectively manage communications with the control system

SOLUTION•

An distributed control system was installed with secondary controllers at substations to handle
the interfaces with field devices•

Approximately 1,400 HART-enabled field devices were connected to the system full-time•

Several traditional 4-20mA anti-surge valves were connected to HART multiplexers to allow theirdata can be converted for communication•

A videoconferencing application lets experts around the world collaborate on diagnosing andcorrecting problems as they arise

RESULTS•

HART technology helped the plant meet a commissioning schedule•

Diagnostic data enhance compliance with the company's Total Reliability Initiative for higher
efficiency, asset availability and safety•

A full-time connection between HART-enabled devices and the control system’s asset
optimization package allows real-time tracking, troubleshooting and fault diagnosis

By designing in the advanced communication and self-diagnostics capabilities of HART technology,
Norway’s Statoil and its partners started efficiently delivering natural gas to the U.K.
When winter strikes, you need heat to beat back the cold. It would be best if the fuel were reliable,
plentiful, and relatively clean burning. Now consumers in the U.K. have a new source for that heat,natural gas and condensate pumped across the ocean from Norway’s subsea Ormen Lange gas field.

118

They’ll warm water for tea, cook food, heat homes, generate power and otherwise use the fuel for years
to come.

Statoil Offshore Plant – Ormen Lange

They’re able to do so, in part, because of HART technology. Erling Ramberg is an automation leadengineer at the Norwegian oil company Statoil. The firm designed the onshore processing facility
that produces the natural gas and condensate shipped to the U.K. He notes that the goal was tobe as efficient as possible and that HART-capable transmitters and valves were chosen for this andother factors.
“It has to do with size of the plant, of course, and the location out on the island. Also, we do notwant to bring in more people than required,” he says.
Up from the Cold, Dark Sea
Discovered a decade ago by one of Statoil’s parent companies, Ormen Lange is a natural gas field
off the Norwegian coast. It’s large in more ways than one. It measures 40 kilometers long andeight wide. It also has proven gas reserves total nearly 400 billion cubic meters, an amountprojected to be able to supply up to 20 percent of the natural gas needs of the U.K. for the next
forty years.

119But Ormen Lange is not easy to exploit. The gas field itself lies roughly 3000 meters below sea
level, buried beneath an uneven seabed and sitting under 800 to 1100 meters of water. Situated
120 km off the coast of Norway, the site experiences some extreme natural conditions. There aresubzero temperatures, whether measured in Fahrenheit or Centigrade, most of the year. The seas
are stormy, with strong underwater currents.

Subsea wells in seabed templates

The project that brought this fuel up from the bottom of the sea and into British homes consists ofa 24 subsea wells in four seabed templates. The output of the wells is sent in pipes 120 km to
Nyhamna on the island of Aukra on the west coast of Norway. There the fuel is processed andreadied for shipment to the U.K. via a 1200 km long undersea pipeline.
Ramberg notes that direct pumping of the fuel to shore-based processing won’t be problematic
because special steps are taken to prevent pipe-clogging due to freezing of the liquid. That’s donewith an on-shore monoethylene glycol (MEG) plant. “We pump the MEG liquid out to the wells,
inject it in the pipelines and transport it with the gas to shore to prevent freezing.”
Meeting the Challenge for Less
Once onshore, the MEG is removed and reused. The fuel then has to be processed and readied forshipment to the U.K.
When designing the plant, Statoil faced several constraints. One was the remote location, anotherwas the sometimes harsh weather, and a third was the size of the facility. As finally built, the onshore plant is one square km, with a main control room and 10 substations. “This plant is quite120

large,” says Ramberg.
An overriding concern in the design was the need for absolutely reliable operation. No one, after
all, wanted a consumer in the U.K. to turn on a burner and get nothing out because of a problem
with a plant across the sea. The company, quite naturally, also wanted to accomplish all of its
goals as efficiently and with as little onsite manpower as possible.

Ormen Lange Onshore facility

Ramberg recalls the technology selection process. Given the constraints, the ability to do
predictive diagnostics was particularly important. With that capability, the health of a valve orother component could be gauged and maintenance could be done as needed. Valves wouldn’t bechanged out too soon, which would waste money. They also wouldn’t be changed out too late,which could potentially jeopardize operations.
There were other benefits to having a wealth of diagnostic information. With the right data, it
should be possible to identify the root cause of a problem. It might then be possible to correct theissue remotely, meaning fewer personnel would be exposed to harsh weather and possibly
dangerous conditions. What’s more the collection of data could, over time, lead to the eliminationof some problems as root causes were identified and fixes implemented.
Because of the advantages of a communication rich approach, the company selected HART
Communication technology to deliver the device diagnostic information they were seeking. The
finished plant has about 1400 separate HART-enabled field devices connected on-line—full time.

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Of these, about 350 are valve positioners, with most of the rest transmitters. A handful of
traditional 4-20 mA anti-surge valves are connected to HART multiplexers so that their data can beconverted for communication.
Control is handled by a DCS with secondary controllers in the substations handling the interface
between local devices and the plant-wide controller. As might be expected given the need forreliability, there are redundancies and intelligent approaches built into the setup. Some of thesearen’t those typically thought of or used. For example, there’s a robust video conferencing
capability so that experts from around the world can meet virtually to help diagnose problems andpropose solutions.

After processing at the plant, the fuel begins a trek to the U.K., traveling 1200 km before arriving
at a terminal at Easington at the other end. “It is a very long pipeline. I think it is the longest
subsea pipeline so far,” says Ramberg.

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Operations Begin
He notes that startup of the operation was an activity that took some time, with an eye toward
full production over a span of months. “The startup was an activity going on for weeks, but theactual startup was when they opened the valve to the well,” he says.
Ramberg adds that HART technology helped the plant meet its commissioning schedule. However,in some sense, his job is done. Starting in December, operation of the plant was taken over by
project partner A/S Norske Shell, the Norwegian member of the Shell family.

Graham Baird, a condition monitoring engineer for A/S Norske Shell, will be one of those responsible formonitoring of the plant’s day-to-day operations and health. He’s had input in the design phase,particularly with regard to what’s needed for operational monitoring of intelligent field equipment
condition.
While there hasn’t been a lot of operational data so far, what the HART-enabled technology hasdelivered is promising. Baird cites the control system’s asset optimizing package and device manager.
“Early indications are that these will give us a lot of useful actionable data, as they are online systems
scanning the HART-enabled instrumentation continuously,” he says.
With alert reporting activated, work can be prioritized, scheduled, and tracked. Baird notes that so far
fault diagnosis has been made very quickly, thereby enabling corrective action to be taken in acontrolled manner. Often, this has allowed fixes to be made directly to the root cause of the problem.

123

There also can be synergies with other non-HART condition monitoring systems. For example,
compressor performance can be influenced by surge valve conditions, instrumentation calibrations, andso on. With more diagnostics data available, it’s possible to cross reference between systems toestablish why equipment may not appear to be performing according to design.
“All in all we get a much better overall view of the plant asset condition right now” sums up Baird.
He explains that the use of HART technology and the wealth of diagnostic information it provides aligns
with Shell’s Total Reliability Initiative. Getting that more informative picture also helps plant operators
rest easier at night, Baird says.
“Having a large number of instruments and valves connected to the HART-based systems for diagnostics
can help us achieve a high availability for safety related instruments, critical process instruments andcontrol valves. This gives plant operators the confidence that they have properly operating control
equipment.”
Thus, an intelligent application of HART technology helps keep the U.K warm. With the predictive
diagnostic capabilities built into the system, the Ormen Lange plant should be able to do so in a costeffective manner for years to come.

2007 HART Plant of the Year124

CLARIANT USES HART TECHNOLOGY TO SOLVE
MAJOR PRODUCTION PROBLEM
PROJECT OBJECTIVES•

Re-configured field devices from a safe area to adapt to a new production batches.

SOLUTION•

Create a centralized system that would allow access to and modification of the HART devices
currently installed in the plant via a Remote Device Management concept•

Centralized access to all devices and centralized the database and management of our
instruments.

•

HART Communication is used to deliver the process measurement values and device
configuration information to a PROFIBUS-Remote-I/O system, which converts the data to cyclic
PROFIBUS DP Data.

•

The data and device information is viewed daily

RESULTS•

Initial investment cost was low since installed devices were HART-capable•

By saving just 2 or 3 hours of downtime, initial investment could be recovered•

Plant engineers have determined that this project has reduced downtime by at least 60-70%•

Changing device parameters to adjust for a new product is now faster and easier•Device problems and errors can now be quickly analyzed•

Accessing data from devices in hazardous area is no longer a problem•

Equipment replacement (when necessary) is now faster•

Predictive maintenance alerts enable problems to be detected within seconds and process
disruptions to be avoided•

Real-time access to field devices provides assurance that things are working properly

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“The return on investment is very high when you use the HART technology that is already in your plant.”
Rather than waiting for a “perfect” solution that may require a significant investment, plant managers
should look at the technologies they already have for a viable solution to improve operational
performance.

The Clariant antioxidants plant in Gersthofen, Germany, solved a major production problem by utilizing
the resources already installed in their plant. Clariant uses HART Communication technology in their
daily operations to deliver process measurement values and device configuration information to a
PROFIBUS remote I/O system, which converts the data to cyclic PROFIBUS DP Data for real-time data
access, preventive maintenance and troubleshooting of critical devices located in a hazardous area.
“The return on investment is very high when you use the HART technology that is already in your plant,”
says Ludwig Wenninger, Clariant plant engineer. “Going to the device in the field took a lot of time. Now
we can access parameters from a central location in a safe area which has reduced the duration ofplanned shutdowns by at least 60 to 70 percent.”
The Clariant plant produces additives used in plastics production and is responsible for prototyping new
production plants. Because of thenumerous chemicals produced,
their field devices need to be reconfigured frequently to adapt toa new production batch. Many ofthe devices are located in ahazardous area, which limits
accessibility, so a plan wasdevised to allow access to smart
devices from a safe, remote (awayfrom the devices) location.
“To create a centralized systemthat would allow access to andmodification of the HART devices
currently installed in the plant, we
decided on a Remote Device Management concept,” says Wenninger. “The system is based on
PROFIBUS-Ethernet gateways and uses several automation technologies working together to provide a
cost-effective solution.”
Since 1995, the Clariant plant has used numerous HART-enabled devices from multiple suppliers.
Because HART technology is defined by a standard specification, all devices were able to be included in
the application regardless of supplier, device age or measurement type. HART provides the means ofremote device configuration to meet two of the projects main requirements.

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Some of the devices were installed in hazardous areas and a notebook PC and other configuration tools
could not be used in those areas. Since accessibility and management of the different devices would
provide faster process adjustments and possibly provide early notification of pending device problems,
the plan needed to provide central access to the intelligent HART devices from a safe, remote location toeliminate the need for routine visits to the hazardous areas.

“We wanted to use the possibility of device adjustments and remote configuration which is built into the
HART devices,” says Wenninger. “We wanted to centralize access to all devices and to centralize thedatabase and management of our instruments. So, we decided on a structure where the devices andtheir information were available full-time and would always be connected to the system.”
HART Communication is used to deliver the process measurement values and device configuration
information to a PROFIBUS-Remote-I/O system, which converts the data to cyclic PROFIBUS DP Data.
The remote I/O from R. Stahl was selected for this application since it is designed as intrinsically safe andcan provide access to devices in the hazardous area.
The link to the hazardous area is a RS-485 intrinsically safe option of PROFIBUS, converting to StandardRS-485 and then to the PROFIBUS Master gateway by Softing and to the Delta V Field Controller suppliedby Emerson Process Management.
“The Clariant project is an ideal example of how to use installed HART-smart devices to their maximum
potential—in other words, finding better ways to use what you have,” says Ron Helson, HART

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Communication Foundation Executive Director. “Real-time integration of HART data with plant control,
safety and asset management systems unleashes the Power of HART technology and provides significant
benefits in all phases of the plant life cycle.”
The data and device information is viewed daily and has provided several expected and unexpected
results.
•

Initial investment cost was low since installed devices were HART-capable•

By saving just 2 or 3 hours of downtime, initial investment could be recovered•

Plant engineers have determined that this project has reduced downtime by at least 60-70%•

Changing device parameters to adjust for a new product is now faster and easier•Device problems and errors can now be quickly analyzed•

Accessing data from devices in hazardous area is no longer a problem•

Equipment replacement (when necessary) is now faster•

Predictive maintenance alerts enable problems to be detected within seconds and process
disruptions to be avoided•

Real-time access to field devices provides assurance that things are working properly

Combining HART with other automation solutions delivers real-time benefits to the Clariant plant 24hours a day, 7 days a week. Re-configuration of the process to include a new product is now much fasterand is accomplished with significantly less time, effort and cost. The ability to diagnose the overall plant
operation is considerably enhanced. Downtime due to device re-configuration has been greatly reduced
and has already provided complete recovery of initial investment.
HART Communication technology is the “right tool” for management of all field devices delivering data
to the control system and device monitoring applications. Justifying the cost for the hardware andsoftware needed for this type of project is easy because the installed HART devices can be used.

2004 HART Plant of the Year128

BP COOPER RIVER USES HART DIAGNOSTICS
TO SAVE ON MAINTENANCE AND INCREASE
PRODUCTIVITY
PROJECT OBJECTIVES•

Gain diagnostic data on hundreds of control valves to pinpoint problems during scheduled
shutdowns•

Migrate to new technology with minimal production downtime for installation•

Make use of existing wiring and be compatible with existing valves and transmitters

SOLUTION•

A phased upgrade to intelligent valve positioners caused “no major disruptions to the operation”•

A multiplexer was added to send digital HART device data to an asset management system,
while also allowing analog signals to pass to the control system.

•

To accommodate an older, analog control system, a converter translated digital HART device
data where needed between HART-enabled positioners and 4-20mA signals.

RESULTS•

HART-enabled devices provided process, status and diagnostic data to provide actual valve
positions, act as control system position switches and eliminate extra field devices and wiring.

•

Plant availability has increased to about 96 percent, and site output rose more than 25 percent
in part due to the use of HART technology•

Plant personnel need only pull five or six valves during a plant shutdown instead of 35 to 50 tosave “hundreds of thousands of dollars per year in maintenance and production costs,” BPreports.

“We are saving hundreds of thousands of dollars per year in maintenance and production costs,” reports
a specialist at BP Cooper River, which supplies one-third of the world’s supply of a vital ingredient in

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plastics. HART technology improves communication from valves to analog and digital controls as well as
maintenance
A. J. Lambert, an instrument and electrical reliability specialist at the BP Cooper River Plant in Wando,
South Carolina, sought to balance two important goals: increasing plant availability without incurring
additional maintenance costs. He achieved his goals,
thanks to the application of engineering expertise, hard
work and HART Communication technology.
The latter, he notes, played a key role. “We know of noother activity that can provide the kind of savings and plant
availability that we are achieving using HART diagnostic
data. We are saving hundreds of thousands of dollars per
year in maintenance and production costs,” he says.
Located approximately 20 miles from Charlestown, the BP
Cooper River Plant manufactures purified terephthalic acid
(PTA), which is used in making polyesters, plastic bottles,
and other items. Thus, while the plant doesn’t make plastic
it does manufacture a vital plastic precursor.
There are two units on the site, one built in 1977 and the other in 1997. Between them they produce
over 2.7 billion pounds of PTA annually, the largest amount of the product from any single location in
the world. The plant accounts for nearly a third of the total global PTA production, with hundreds of
employees and contractors on site. The Cooper River Plant runs 24 hours a day, seven days a week.
However, it doesn’t run all the time. Periodically, BP has a planned shutdown so that needed
maintenance can be done. These scheduled shutdowns cost millions of dollars a day per unit. Before
2001, the plant would undergo a shutdown for maintenance purposes every couple of years.
During those times, the plant’s maintenance and engineering staff would pull 35 to 50 control valves outof a total of few hundred in both units. They selected the valves to pull based on various criteria,
including past history and an assessment of wear and use from the manufacturing process. They didn’t
have specific information pinpointing, which, if any, valves were causing problems.
As part of a plant-wide drive to lower expenses and increase availability, Lambert started looking at
items that had the highest maintenance cost. After going over records for the unit built in 1997, Lambert“… identified 50 of the more critical control valves.”
Getting information on the health of those valves could be vital in meeting the overall goals of the
Cooper River Plant. That meant intelligence had to be added to the valves, which in turn required theuse of new technology. Any upgrade, though, had to meet certain criteria. Migration had to be easy andnot interrupt current operations for any significant length of time.

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The investment needed to be minor and benefits readily attainable. Those parameters implied that any
solution would have to run over existing wiring and be compatible with the mix of valves andtransmitters already in place, a combination that varied by plant unit. For instance, at the time the 1997
unit had smart transmitters but no smart positioners and an analog control system. The 1977 unit had adifferent blend of technologies.
Getting Smart
Around 2000, BP had spent thousands of dollars installing diagnostic software. At the time the project
had been justified in order to get information from a single valve. That installation introduced the HART
Communication protocol into the plant, and Lambert started looking into getting valve diagnostics fromother locations using the HART signal. After a bit of investigation, Lambert and others were convincedthat not only could this be done but that it could be done using the wiring already in place.
Therefore, they proposed a HART-centered upgrade, which plant management approved. The project
was completed over the next few years without a problem. “The upgrade to intelligent positioners wasphased in over time with no major disruptions to the operation,” says Lambert.

Because of differences between the units, various hurdles had to be overcome. One was the analog
control system in the 1997 unit. The BP team solved this through the use of a converter, whichtransformed digital HART data from the positioner into 4-20mA signals that the analog control system
could understand.

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That same data, sans conversion, eventually also had to go into an asset management system thatwould eventually provide intelligence, data for analysis, and other benefits. For that, they used amultiplexer, sending digital data to the asset management system while allowing the analog signal to go
to the control system.
Another hurdle involved handling valve position feedback. For that, the Cooper River Plant staff selectedinterface instruments to extract process, status and diagnostic data from the HART transmitters andvalves. These provided actual valve position feedback and acted as position switches for the control
system. They also eliminated the need for extra field devices and wiring.
By mid-2004 all of the positioners in the 1997 unit had been upgraded, while 10 percent of those in the
1977 unit were smart. While far from complete, the figure for the older unit includes the most criticalcontrol valves. Also at that time, some 150 transmitters and 125 valves were connected to the AMS.
Benefiting from Brains
The payback for this work, notes Lambert, shows up in a number of areas. For one thing, there’s been a
reduction in valve maintenance costs. Whereas before, some 35 to 50 valves would be pulled during aplanned plant shutdown that number has now been cut to only five or six. The maintenance andengineering groups know also why the valves should be yanked out of production before they’re pulled.
The annual cost savings for this more accurate maintenance is in the hundreds of thousands of dollars.
Through the use of HART monitoring, the plant’s staff is able to monitor the health of half a dozen
critical valves. They’re notified if those valves show signs either of freezing or overheating, allowing
preventive measures to be scheduled and taken. This prevents those valves from causing unscheduled
shutdowns, which can be very costly.
As a result of the upgrade, plant availability has increased to about 96 percent. One consequence is anincrease in output. The installed capacity of the two units was originally 2.2 billion pounds a year.
Through these and other improvements, that production has now risen to 2.76 billion pounds a year, an
increase of more than 25 percent.
In the future, additional benefits are expected. Plans call for both engineering and operations personnel
to begin using the data collected by the smart instrumentation to pin down problems and spot trends.
By taking action based on this ongoing analysis, availability should go up and costs come down evenmore.
So the smart control valves, transmitters and HART Communication have led to both more paper, in theform of monetary savings, and more plastic, due to the increased plant output. The lesson for Lambert isthat the payoff of the right solution to a problem could be large. “Get control of the items that touch the
product and you can save some big money,” he says.

2004 HART Plant of the Year132

NEW YORK POWER UTILITY USES HART TO REDUCE COSTS
AND IMPROVE RELIABILITY
PROJECT OBJECTIVES•

Monitor and control pressure data•

Enable monitoring of AC power status, which 4-20mA analog wiring could not do•

Reduce costs by eliminating a remote terminal unit (RTU) or programmable logic controller (PLC)

SOLUTION•

Eliminated the need for a mini RTU or PLC at each remote measurement site•

Eliminated the need for as well as an analog modem at each remote measurement site

RESULTS•

Saving approximately $700 per site•

Facilitates future improvements to reliability, redundancy and regional customer service

Public infrastructure projects are necessary but power utilities face ongoing challenges to provide themost reliable, cost-effective service possible. In keeping with this need, Mark Viglucci at the public power
utility of National Grid, Niskayuna, N.Y., used HART technology to reduce costs and improve reliability.

What Needed to Happen
The evolution toward digital communication raised the possibility of finding more cost-effective ways tomanage Supervisory Control and Data Acquisition (SCADA) systems than to continue using a traditional
4-20mA remote terminal unit (RTU) or programmable logic controller (PLC) at each remotemeasurement and control installation. Additionally, Viglucci found that traditional analog wiring could
not handle all monitoring jobs needed for SCADA system troubleshooting and field diagnostics.
“Typically these sites have two pressures and one DI alarm for AC power status. Unfortunately, the AC
power status can't be monitored,” he said.

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The Solution
Viglucci decided to use HART technology in an experiment to eliminate unnecessary hardware in theutility’s SCADA system. At two sites, for example, three transmitters were being polled at two different
sites by a compact programmable SCADA RTU/controller transmitting data across leased analog datalines.
For signal level and four-wire to two-wire conversion, he designed “a simple interface board containing
only four ICs,” with the telephone company providing the bridging to allow multiple stations andnumerous HART transmitters to be polled (using long-frame addressing), and data to be received in realtime.
Benefits and Outcome
The test was a success. Eliminating a controller (RTU or PLC) and analog modem, per-site savings are$700, according to Viglucci. AC power can now be brought into the maintenance program for greatersystem reliability. This strategy sets the stage for cumulative savings as sites are added or retrofit, while
laying the groundwork for National Grid to make continual improvements in serving its customers.

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OHIO STATE UNIVERSITY USES HART TO REDUCE RISK TO
PRODUCTPROJECT OBJECTIVES:•

Improved diagnostics through greater visibility of instrumentation and process•

Improve consistency of process performance with more efficient maintenance•Speed troubleshooting and corrective maintenance for greater process consistency•

Better manage instrument configurations to reduce risk

SOLUTION:•

Installed approximately 250 HART-based devices, with automatic loading of tags and operating
information by a HART-enabled DCS•

Integration with DCS asset management software

RESULTS:•

Saved a potential $300,000 (USD) superheater replacement by using HART data to convince
vendor to instead address faulty valve controls•

Enhanced maintenance responsiveness with context-specific notifications such as “primaryvariable (PV) was out of sensor limits” or “bad: check measuring”•

Protected process integrity by validating analog readings with digital HART data to trigger eventsand investigation of discrepancies•

Broadened quality assurance through tracking of PV drift using PV validation (above)•

Enabled increased fault monitoring using automatic redundant formats

The Ohio State University’s McCracken power plant provides 85% of the campus’ steam-based energy.
“Without HART, this plant wouldn’t operate,” says Jerry Lowery, control systems engineer. Better data
visibility helped to ensure process consistency and instrument reliability for greater productivity andbetter maintenance.

135

“Being able to effectively manage our instrument configurations reduces our regulatory risk and our risk
to product,” says Jerry Lowery of The Ohio State University (USA) as he attests to the essential value of
HART Communication in industrial automation applications. One benefit he names is that mosttechnicians are familiar with HART-enabled communicators.
“The technicians just love them. They’re superior for the technicians,” he says. Another importantfeature for Lowery, who is a control systems engineer for the university’s McCracken power plant, isthat HART is an open standard. “It gives everyone a common thing to work toward. HART is the way togo. It makes life so much easier.”
Operating continuously, the McCracken plant provides 85% of the Buckeye campus’ steam-based energy
needs. The steam is used for heating, humidification, sterilization, chilled-water, and domestic hot-waterproduction.
The plant has five industrial boilers, a Babcock & Wilcox D-Style, 600-psi, 220,000 lbs/hr unit, and four
200-psi Nebraska D-style units that produce 150,000 lb/hr of steam. Co-located at the plant are ten Yorkchillers producing 16,000 TR/hr, and three Caterpillar emergency diesel generators with a rated total of
6,300 kWH.
Lowery doesn’t mince words about how important HART technology is to the plant. “We haveapproximately 250 HART-enabled devices. Without HART, this plant wouldn’t operate,” he says. HART
also helps the plant’s technicians save time finding instrument problems. “We don’t have to spend asmuch time looking for what’s wrong,” Lowery adds.
In one instance, staffers observed intermittent signal failures on a temperature transmitter on one
boiler’s superheater (SH) vent control, which caused the vent to go into the wrong position. However,thanks to a HART-enabled DCS system on the Nebraska boiler, they were able to quickly correct the
problem.
Intermittent signal failures are some of the more difficult field problems to diagnose as the problem may
only happen occasionally for no apparent reason. ”Before having continuous HART monitoring ofdevices, we would have to guess at the problem if it wasn’t apparent and start replacing items (sensor,
transmitter, or analog input) to see if the problem would go away, says Lowery. “With HART and theability to continuously monitor the HART signal from the device, we are able to log the issue in the
DCS/Asset Management software and go out and correct the actual problem.
“We have two quad operator stations with four human-machine interface (HMI) screens and four others
where HART data appears via the DCS,” he explains. “This was the first time we’d seen this type of HART
information.”
The displayed spreadsheet showed data which has a log/time-stamp describing an event. In this case,descriptions included “primary variable (PV) was out of sensor limits” or “bad: check measuring” and“field device malfunction.”136

Once the staff learned of the event descriptions in the event log, they were able to solve their problem
the same day. “We knew exactly what was wrong. The technician went out and repaired the resistancetemperature device (RTD),” Lowery says, adding that with their HART-enabled DCS, “our technicians
know exactly what the problem is.”Results Proven, Risks Lessened
A second occurrence at Ohio State involved a Superheater (SH) vent-control valves failure. The boiler
superheater vent valve wouldn’t open or would become stuck while partially open, Lowery recalls. “Avent-control valve failure put the boiler superheater at risk.”
Lowery’s solution was to use the HART Protocol’s digital PV (DigPV) that was accessible from the DCS. He
used the valve positioner digital PV to validate the valve’s position. He says if the valve didn’t reachproper position within 30 seconds, an alarm would sound and a warning would simultaneously bedisplayed on the HMI screen.
The DigPV, which proved that the valve was not seating properly, and the digital secondary variable(DigSV), in this case positioner temperature, indicated that a temperature “over range” had occurred.
“The HART secondary value or device temperature on the original positioner was trended and used toprove that the device had never exceeded its maximum operating temperature of 50 ºC,” says Lowery.
The data convinced the vendor to replace the valve positioner, “and the problem went away.” This isimportant because the vendor originally claimed the boiler’s operation had overheated and caused theSH vent-control valve to become stuck.

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Armed with their HART-enabled DCS evidence, Ohio State got the vendor to fix six SH vent valves saving
approximately $10,000 (USD). Also, the combined digital PVs’ and SVs’ performance not only saved apotential $300,000 (USD) cost of replacing the existing superheater, but also led the vendor to install amore reliable positioner.
Lowery appreciates this digital value functionality. “Digital PVs are extremely valuable in critical loops tovalidate the analog position with the digital position,” he says. In addition to diagnostics, having both
analog and digital communication available simultaneously with HART is of particular value to Lowery.
“This capability is extremely important when validating loops. We use the digital PVs to validate analog
PVs on critical positioners. It just tells us what is wrong with the device,” he states. “And on criticalloops, if the analog PVs and digital PVs don’t match up within a certain percentage of each other, we
alarm that loop and have operators investigate the actual valve position.”

The simultaneous analog-digital capability of HART fulfills one of the most obvious asset management
functions of HART-enabled automation—protecting equipment and keeping plants operating.
Of the 250 HART-enabled devices at the McCracken plant, an asset management system (AMS) monitors
188-200 of them. With a separate server, the AMS has a processor and input/output (I/O) modules. “Theasset manager monitors and tracks device faults for all HART-enabled devices. Types of device faults —anything you can think of,” he says.
Overall, diagnostics are much improved. “Our asset manager package tracks faults that occur in HART
devices through our DCS. Small items, like a positioner losing its zero position, are now caught early andrepaired,” Lowery says. “But without that asset management software, the problem might have neverbeen corrected because it wouldn’t have been seen until complete device failure.”138

Correct monitoring, particularly with HART-enabled instruments, also concerns Lowery, who offers tips
for users. “HART device diagnostics is only as good as the vendor’s device description (DD) file. The moredetailed the DD file, the more diagnostics you’ll have.”
Lowery also suggests insuring that the DCS analog I/O is HART-enabled. “Using a third-party solution to
strip out and send HART data via a serial connection will likely prevent using HART digital PVs in a fastchanging loop,” he says. Caveat emptor (Let the buyer beware!) is his advice regarding proprietaryfunctions in HART devices.
“Some vendors tweak a HART DD file to their advantage, so you’ll use their DCS with their HART
devices,” Lowery says. He advises users to make sure all functions are accessible.
“Check that the DD file registered at the HART Communication Foundation is the file that the vendor
distributes. Also, consider joining the Foundation. DD files from the Foundation are tested to be surethey are compliant to the standards.”
Ohio State’s experience with HART was so positive that, according to Lowery, the university has only
scratched the surface of using the protocol. For quality assurance, the power plant’s staff is examining
tracking the drift of the analog PV compared to the digital PV. Also, there’ll be more use of HART device
diagnostic faults in the control strategy. Adding this tracking ensures agreement between the digital PV
and analog PV readings.
Ohio State also plans to evaluate using a field device manager (FDM) for configuring HART devices,rather than using HART communicators. How will that affect operations? “It will help us catalog devices.
We’re told that if you replace a device, when you plug it in, the DCS will automatically load its tag andother operating information,” Lowery says.
Finally, through its asset manager, the university will increase fault modeling at McCracken. What partwill HART play? “All HART devices can tell you if there’s a fault,” Lowery says. “We can go to redundant
format automatically.” That’s important, he notes, because the analog PV value could be in error.

139

APPLETON PAPER USES HART TO IMPROVE ASSETMANAGEMENT AND SAVES $40,000 ON WIRING ALONEPROJECT OBJECTIVES•

Minimize costs for hardware, software, training, spare parts, etc.

•

Find a simple, robust system to inform staff about the device health and use that system inother applications.

•Get a database for configuration, tracking, troubleshooting, etc.

•

Obtain access to all instrument/device data.

SOLUTION•

Integrate HART Communication with distributed control system (DCS).

•

Install more than 100 HART-enabled flowmeters, control valves and pressure sensors
throughout the facility.

RESULTS•

Improved instrument configuration and preventive maintenance capabilities•

Lowered operation and maintenance costs•

Accessed multivariable mass flow information•

Realized enhanced device diagnostics•

Improved control-loop validation•

Increased plant availability•

Enhanced regulatory compliance•

Achieved higher product quality and product yield

Pulp-and-paper producer Appleton Paper used HART technology in a major upgrade of their papercoating operation as the catalyst for improving asset management. The company installed more than
100 HART-enabled flowmeters, control valves and pressure sensors at its facility in Appleton, Wisconsin,
with positive results.

140

“HART gave us the best opportunity to expand with the rest of our existing control systems at the lowest
costs,” says Chris Van Sambeek, Appleton control systems technician.
The papermaker targeted several criteria for the project: minimize costs for hardware, software,training, spare parts, etc.; find a simple, robust system to inform staff about the device health; use thatsystem in other applications; get a database for configuration, tracking, troubleshooting, etc.; andobtain access to all instrument/device data.
Appleton uses HART Communication via a PLC and a HART-enabled I/O system to link the smart
instruments to an asset management system. With the enhanced troubleshooting capability that HART
technology provides, Appleton has improved its instrument configuration and preventive maintenancecapabilities.

“HART technology saved us roughly $40,000 on wiring alone with its ability to pull multivariable
information from our mass flowmeters,” says Sambeek. Appleton has also saved time and money by141remotely configuring devices. HART technology saved the company another $10,000 because they now
need 12 fewer pressure and 12 fewer temperature transmitters.
Sambeek says HART also improved operations in other areas including “better diagnostics; control-loop
validation by pulling information into the PLC through the HART signal; increased plant availability;
better product quality and utility; higher product yield; lower operations and maintenance costs; andenhanced regulatory compliance.”
Finding a new HART smart card that the PLC system could use also helped Appleton. This card allowed
the company to upgrade existing systems with minimal equipment and costs, says Sambeek. “Most of
our existing instruments are HART-enabled, and the HART cards used are compatible with our existing
control systems.”
Installing an OEM’s HART-enabled cards into the control PLC platform allowed Appleton to use HART
data in both the asset management and control systems. “HART provides additional information notavailable to normal analog systems,” Sambeek adds.
“HART has been very effective,” says Sambeek. “We succeeded because the HART Protocol is a better fit
for expansion than other fieldbus technologies.”142

FRASER PAPERS GAINS PREDICTIVE MAINTENANCE EDGE
USING HART VALVE POSITIONINGPROJECT OBJECTIVES•

Connect HART-enabled valve positioners to a single central computer•

Integrate the newly accessible control valve position data into a predictive maintenanceprogram

SOLUTION•

HART-based positioners were linked to a multiplexer using a HART-enabled interface modulewith additional hardware and software•

Import and archive critical data such as valve signatures and operational data•

Operational and diagnostic data coming through the multiplexer were presented to control aswell as device-managing system software

RESULTS•

The maintenance system provided critical benefits in diagnosing problems during outages aswell as ongoing preventive maintenance benefits•

By avoiding direct PC and handheld calibrator contact at the field level, HART technology
reduced the risk of creating an upset to the process, and also reduced maintenance man-hours•

Using HART Communication and interfacing digital valve positioner data using a multiplexer
allows a Canadian paper mill to increase efficiency, improve data retrieval and perform
continuous remote diagnostics.

Many end users have realized the benefits of installing HART-based control valve positioners and using
HART technology to integrate the positioners with their central computer system. Fraser Papers, adivision of Thurso in Quebec, Canada, standardized its paper mill on HART-based positioners as the firststep in a proactive maintenance program.

143

In June of 2000, the mill wanted to connect all of its HART-based positioners to one central computer.
An integration package consisting of digital products and software solutions allowed the mill to realize
the full benefit of their HART Communication investment.
The solution was to link all HART-enabled positioners to a multiplexer (MUX) using a HART-based
interface module in addition to other hardware and software components. The MUX allows the facility
to use computer software to oversee all of its digital positioners in the mill and link the information in an
effective device management system.
Fraser Papers began to realize significant benefits soon after implementing the HART-enabled device
management system, including increased efficiency, easier retrieval of information and continuous
remote diagnostics.

“With this system in place, our maintenance technicians can quickly access the device to calibrate andcreate electronic maintenance records,” says Mario Leclerc, Fraser Papers instrumentation engineer.
“This reduces the risk of creating an upset to the process by avoiding a PC or handheld calibrator
connection to the loop terminals. It also helps us manage man-hours more efficiently.”

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Archiving information (such as valve signatures and continuous operational diagnostics) in maintenancerecords allows technicians and maintenance engineers to implement a program of preventive
maintenance on control valves in various sectors of the mill during outages.
Using the dial-up modem or through the Ethernet, personnel can remotely troubleshoot valves orrequest remote assistance from the positioner manufacturer. This helps determine whether to pull thevalve out or simply do minor corrections. The maintenance software can generate step tests of varying
amplitudes, making it easy to validate valve responsiveness online.
Using the online diagnostic capabilities of the positioners, the MUX is able to acquire information
seamlessly. This, in turn, simplifies the implementation of a preventive maintenance program, based onrecorded mean-time-between-failures. These continuous diagnostic values allow the user to determine
if the valve selected is adequate for the service. They can also determine premature trim wear, using thetime-near-closed counter.
HART-based technology has opened new doors to help run plants with less downtime while providing amechanism to transport critical information from field devices over existing field wiring. The
implementation of a HART system similar to that installed at Fraser Papers is the key element in
implementing a predictive and preventive maintenance program.

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SWEDISH PULP AND PAPER PLANT USES HART TECHNOLOGYTO IMPROVE PLANT AVAILABILITY
PROJECT OBJECTIVES•

More efficient, effective calibration of field devices•

Higher data availability without the up-front investment in digital field networks.

SOLUTION•

Enhanced connectivity from control room to instruments•

HART-enabled devices can be installed anywhere on the 4-20mA control loop.

RESULTS•

HART technology eliminated a 30-minute trip to the field for any given device.

•

Calibration now done from the safety and comfort of the control room.

HART technology saves trips to the field for improved plant availability. That's what user Jimmy
Andersson, found when he upgraded existing control loops with HART protocol-compliant
instrumentation at a pulp and paper plant operated by Vallviks Bruk AB in Söderhamn, Sweden.

As with many users, the Swedish plant needed a way to upgrade its 4-20mA analog wiring without theexpenditure in full digital field networks. Without effective calibration and data access, plant operations,asset availability and quality compliance suffer.
The Solution
Handheld or PC-based HART-enabled devices/applications that can be installed anywhere on the 420mA control loop help Andersson save time and reduce costs. “Now I don’t have to go out in the field
to check if a specific instrument is 'alive',” he says. A trip to the field averages about 30 minutes per
device. Multiplying the number of devices accordingly multiplies the savings.

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Benefits and Outcome
According to Andersson, HART technology improves operations, specifically enhancing plant availability
and quality compliance. “The greatest benefit is that I can calibrate instruments from inside the control
room,” he says, which is “a lot safer and more comfortable than doing it out in the field.”
HART Communication has reduced configuration and set-up time as well. “Before HART we had tocalibrate the instruments out in the process. Now we can do it right where the signal goes into thecontrol system,” Andersson says. After initial implementations, the plant's plans with HART technology
expanded to the start-up of a new turbine.
According to Andersson, using HART technology for data including instrument calibration has improved
the performance of controls for improved plant operations, asset availability and quality.

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BRAZILIAN STEEL PLANT USES HART COMMUNICATION TO
REDUCE DATA RETRIEVAL TIME
PROJECT OBJECTIVES•

Faster, more complete access to data•

More data visibility for process management and instrument maintenance•A cost-effective solution for an existing plant

SOLUTION•

HART-enabled control, software and asset management systems•

Handheld communications devices (Models 275 and 375).

•

PC Anywhere for remote off-site access.

RESULTS•

More data available to personnel on off-hours—including technicians at home—to assist atplant personnel as needed.

•

Time and money savings through faster configuration and modifications.

•

Changing a range in a traditional analog setting once took an hour; it now takes five minuteswith HART technology.

HART technology helped engineers and technicians at a COSIPA plant in Sao Paulo, Brazil, more
effectively configure and access data to better manage field devices across the automation network. In
fact, some tasks that once took an hour to complete now take five minutes.

What Was Needed
Personnel at this existing plant needed faster data access for process management and instrument
maintenance.
The Solution

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HART-enabled process control and asset management systems plus handheld communications devices(Models 275 and 375).
Benefits and Outcome
To calculate the cost savings in time and money realized by the COSIPA plant, we must first note that in
Brazil a technician earns the equivalent of $10 USD per hour. Using HART Communication saves theplant about one hour on each device and there are 200 devices in the plant.
According to user Marcos Martins, when with traditional 4-20mA wiring, “I spent one hour just tochange a range. I spend five minutes to do this same task with AMS.” Equipped with HART
Communication, the asset management system provides the user with instant visibility.

Eliminating trips to the field has significantly sped setup time for Martins’ technical team. Instead of
traveling to a device in the field, opening it and working with configuration tools there before heading
back to the workshop, a technician can cut an hour down to 20 minutes using the HART- enabled asset
management system without leaving the workshop.

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HART information, of course, travels wherever the network takes it. Martin says, “With PC Anywhere
and the asset management system, I can work from my house to see the diagnostics, configuration andprocess variables at the plant, 24/7.” The same goes for all plant personnel off their shift, who might becalled upon to solve problems on an ad-hoc basis.

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AECOM CANADA USES HART COMMUNICATION TO KEEP
WATERWAYS CLEAN
PROJECT OBJECTIVES•

Prevent unplanned discharges of sewage to keep waterways clean•

Avoid fines that result from tightening regulations•

Find the most cost-effective and accurate system so the system can be widely replicated.

SOLUTION•

HART-enabled remote terminal unit and instrumentation at each site•

HART communications card and IP-addressable Ethernet data radio at each site for remote
access•Standard single-wire, single-bus connection for a faster, more accurate multi-variable data pathto magnetic flowmeters and pressure transmitters

RESULTS•

Full access to multiple variables from field instruments on a single wire.

•

Significant time savings over the use of separate 4-20mA wiring.

•A reliable defense against potential 100s of thousands in regulatory fines.

•

Future-proofing: Engineers can change their control strategy without running new wires or rewiring their systems.

•

With WirelessHART technology solutions now shipping, future installations will reap additionalsavings by eliminating physical wiring labor, time and cost.

Few cities use modern technology to monitor and detect leaks, particularly as sewerage travels acrosswaterways. Facing tightening environmental and regulatory requirements, AECOM Canada, Ltd., in
Winnipeg, Manitoba, designed and created first-case system using HART Technology to address theissue.

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To prevent unplanned discharges—leaks—in its sewage system, particularly at river crossings, one city in
Manitoba, Canada, called upon engineering firm AECOM Canada, Ltd., Winnipeg, to design and test afirst-of-a-kind monitoring and detection system. HART technology proved critical in speeding
implementation and providing the flexibility to reconfigure the system without the time or expense ofphysical rewiring,
The particular challenge was to monitor force-main sewer lines at river crossings, where gravity cannot
lift material through lines and low-pressure pumping (10 to 15 psi) is a common solution. Despite
tightening environmental regulations, engineers could find no existing solutions. Most cities rely on
visual inspection—a poor substitute for technology because contamination can leak for weeks before aproblem is detected, damaging waterways and drawing regulatory fines.
Unfortunately, "very few" cities have applied modern monitoring solutions because, says AECOM's Kent
McKean, senior automation designer, and a viable commercial solution couldn't be found.
The Solution
McKean's team used a basic architecture involving instrumentation connected to a remote terminal unit
(RTU). The RTU was equipped with an IP-addressable Ethernet data radio at each site to remotely accesssite data and a HART communications card.
McKean and team decided that for test installations, they would specify a system that would “give us
flexibility, perhaps more flexibility than what we actually needed” because there was no way to“definitively predict” which system design would work best.
In mid-2007, the first test installation went online using magnetic flowmeters sending data to the RTU to
be totalized and compared with data points coming in eight- to 10-hour increments. The HART protocol
would prove its value in providing that flexibility when McKean's team decided on a "change inphilosophy" that would require reconfiguring the system to provide instantaneous, real-time data in
addition to the existing totalization strategy.

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This change "was easily accomplished because we had selected HART," says McKean. Instead rewiringand reconfigure physical equipment, he says, "HART technology and the system's software put all of thevariables we needed at our fingertips." The change in data handling led to an increase in resolution from10 to 15 liters per second, to one or two liters per second.
Late in the summer of 2008, the AECOM team installed a second test-site system using the same
strategy but switching from flowmeters to smaller, easier-to-install pressure transmitters measuring thepressure inside and also in the interstitial space. This enabled users to pinpoint the location of a leak as
well as its failure mode, such as whether the exterior or interior pipe has failed. This solution was lessintrusive and provided easier, safer access; reduced maintenance trips by several hours; and slashedsystem cost from roughly $500,000 to between $30,000 and $50,000 per crossing, according to McKean.
Benefits and Outcomes
HART technology provided “much higher accuracy and resolution” than 4-20mA analog wiring while
requiring no hardware and only minor software changes to accommodate the upgrade from totalization
to instantaneous data monitoring. The same benefits can, in turn, reduce the cost of future upgrades. "If
we had gone with a non-HART solution or a non-data bus solution, we would have been very limited in
the data that we could have gotten,” McKean says. “We would have had to use a separate radio or datachannel for each variable that we may need, or we would have had to change things on the fly as wewere developing.”“If we were to implement this system today, we would utilize WirelessHART,” McKean says.

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DETROIT WATER DEPLOYS HART TO
IMPROVE CUSTOMER SATISFACTION
PROJECT OBJECTIVES•Redundant metering systems would register different volumes, which led to billing disputes.

SOLUTION•

Modernize and unifying the point of sale metering system and transmit the data in real-time to
DWSD and every wholesale customer.

•

Use existing analog instrumentation and the skill set of our technicians while providing us thebenefits of a state-of-the-art digital and paperless metering system.

•

Distribute the totalization function to a lower, HART-enabled smart device level, instead of the
traditional PLC/RTU device.

RESULTS•

Complaints about low water pressure have been virtually eliminated since a majority of thesecomplaints have been attributed to faulty regulating valves operated by our wholesalecustomers.

•

Safety has also been improved since the need to enter the OSHA regulated confined space of
the underground metering facilities for troubleshooting purposes has been greatly reduced oreliminated..

•

Metering data obtained from the HART-instrument is communicated and stored in digital form,
eliminating paper-based recordings.

•

A digital packet radio network, which functions like a wireless intranet, is used to “carbon copy”
all metering data to redundant data historians and to SCADA PCs that DWSD provided to eachcustomer.

The need for having redundant metering systems has been eliminated since the same metering datareported from our HART-based instruments to the RTU, is “carbon copied” every five minutes directly154

from the on-site RTU to DWSD as well as to our wholesale customers within a few seconds – we provided
a SCADA PC to each wholesale customer. This has already contributed to improved customer satisfaction.

“HART has served us so well by utilizing all of our existing plant assets.”
By Dennis L. Green, P.E.
Head Water Systems Engineer
Detroit Water and Sewerage Department (DWSD)The Detroit Water & Sewerage Department (DWSD) is the third largest water and wastewater utility in
the United States. DWSD provides services to nearly 1 million Detroit residents and, on a wholesalebasis, to over 3 million suburbanites living in the surrounding areas.
To determine water consumption at the point-of-sale, we had installed metering systems. Our point-ofsale metering systems included a variety of traditional instruments such as mechanical meters, venturis,orifice systems, magnetic flowmeters and chart recorders. Likewise, our wholesale customers had
installed their own point of purchase metering systems, acting in parallel, to make their own
measurements. Very often, the redundant metering systems would register different volumes, which led
to billing disputes.
The solution was modernizing and unifying the point of sale metering system and transmitting the data
in real-time to DWSD and every wholesale customer. An essential and critical part of the multi-million
dollar modernization project was implementing an automatic meter reading/supervisory control anddata acquisition (AMR/SCADA) system that relies on the HART global standard to deliver consistent,
reliable data on system performance.
The innovative application of HART technology enabled us to use existing analog instrumentation andskills set of our technicians while providing us the benefits of a state-of-the-art digital and paperlessmetering system.
Today, the HART standard based digital metering system has not only improved the reliability of ourwater metering operations but has also provided our customers with greater satisfaction by virtuallyeliminating billing disputes caused by metering problems. As a bonus, our new HART based smart
instruments also provide additional flexibility to make on-line configuration changes including
calibration, perform calculations and support real-time remote diagnostics.
DWSD Services
With an operating budget of over $350 million, DWSDs’ services extend well beyond the Detroit city
limits to an 8-county area of more than 1,000 square miles including approximately 43% of Michigan’s
population. DWSD, which is a branch of the City of Detroit government, employs about 3,200 persons
and has the fifth lowest combined water and sewerage rates per month amongst the 20 most populated

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cities in the United States. DWSD operates five water treatment plants pumping an average of 655
million gallons of clean drinking water each day, peaking at 1.5 billion gallons per day.
DWSD serves about 90 wholesale customers representing about 137 suburban communities via nearly
300 underground metering facilities. Figure 1 illustrates one such underground metering facility. These
metering facilities typically include flow and pressure measuring instruments, valves and actuators tomonitor and control the flow of water to the wholesale customer.
Akin to custody transfer stations, these metering systems, which include approximately 750 smart
instruments, provide valuable inputs to detect and compute water usage, and hence billable sale toeach wholesale customer. Since the metering systems are critical for billing purposes, we often refer tothe meters as our point-of-sale “cash registers”.

Figure 1. Typical underground metering facility

Need For a New Metering System
Prior to implementation of the AMR/SCADA project, the metering facilities included a variety of
traditional instruments such as mechanical meters, venturis, orifice systems, differential pressuretransmitters, sonic meters, magnetic flowmeters and chart recorders. The existing metering facilities
used no electronics with the mechanical meters, and all other instruments used chart recorders andmechanical pulse totalizers.

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Thus, recording of all metering data was paper-based and collected manually bi-monthly or weekly byhuman meter readers. Various instrumentation companies including Smar, Endress+Hauser, and ABB
manufactured these instruments.
By the mid-1990s, however, many of our wholesale customers had concerns over their water
consumption data. They elected to install their own point-of-purchase “cash registers” to collect more
frequent readings and validate their DWSD water bills. The point-of-purchase “cash registers” included
redundant metering systems measuring the same water flow and pressure as DWSD recorded on ourpaper chart recorders. Quite often, the two metering systems disagreed over the water consumption
data.
Moreover, the resolution of the chart records was insufficient to prove one party’s assertions over theother, the simple odometer-type totalizers provided no profiles of the consumption data between visits
by our meter readers, and all humans make occasional mistakes when recording data. The
disagreements over a mutually acceptable set of measurements resulted in billing disputes, customer
dissatisfaction and loss of thousands of dollars in revenues.
Acquiring Leading Edge Technology to Improve Customer Satisfaction
DWSD decided it must modernize and unify the point-of-sale metering system and improve customer
satisfaction. Our goal was to eliminate dispute-causing devices such as chart recorders and mechanicaltotalizers and replace them with a digital and paperless metering system specifically to:1) Improve dependability, accuracy and confidence in the metering data by recording meterreadings every 5 minutes – Objectives were ending the practice of our wholesale customers
installing their own redundant metering equipment that often disagreed with DWSD’s, leading
to billing disputes. Failure of any single component of the system must not disrupt system
performance, any recording of data, or any calibration work of the meter technicians –excepting the one failed meter register.
2) Preserve metering data integrity – Data consistency must be maintained throughout thesystem. The same consumption data must be concurrently provided to DWSD as well as eachwholesale customer. In addition, there must be opportunities to recover data when failuresoccur.
3) Archive 10-years of meter data in redundant historian systems for efficient storage andretrieval, engineering analysis and process improvement.
4) Provide an intuitive, easy-to-use, user interface to assist our staff in the setup and calibrationof the meters while automatically documenting the data for certification of our “cash register” the billing meter. Minimal reliance on paperwork to share information throughout the system
by storing the calibration reports in the database of the AMR/SCADA historian.
5) Reduce operating costs of the Meter Operations Division by standardizing on the equipmentused and by controlling software revisions.

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To get the maximum out of the investment in the meters, they are usually sized for predicted future
consumption that may or may not develop. By using peak hourly consumption data, rather thanmaximum meter capacity, a more equitable rate formula can be established based on peakconsumption. In addition, the range of the instruments can be set based on actual peak demands toimprove the accuracy of the instruments as the technicians have a basis for making their range
adjustments as consumption increases or declines over the years.
DWSD is owned and operated by The City of Detroit and has had to resist frequent regionalization
attempts by some of its suburban customers. Being a rate funded utility and having to defend those
rates annually, the project risk and overall installed costs were of paramount importance to ourmanagement. Any proposed solution incorporating the latest and greatest technology had to addressrisks and costs satisfactorily and, in addition, had to address the risk of failure. That is, a backup plan had
to be developed and approved by our management in case the proposed solution did not function asplanned.
Demand Based Rate Model
In addition to the above described project objectives, Stephen Gorden, former director of DWSD, hadexpressed a desire to use the modernization project for restoring DWSD’s traditional position as anindustry leader. His vision was to introduce a demand based water usage rate model in the water utility
industry. More specifically, he wanted a system that would support the development of a demand based
rate model, similar to the model(s) used by the electric utility industry, where there is an infrastructure
charge based on peak load and a consumption charge for total usage. This requirement implied that the
new metering system was capable of performing and preserving multiple reads every hour to identify
the peak hourly demand.
Developing a New AMR/SCADA System by Leveraging HART Technology
Before launching the project to modernize the point-of-sale metering system, we had recognized theability to calibrate instruments remotely and on-line as an important function to improve reliability andconfidence of metering data. By 1996, we were well underway to implement an instrument upgrade
project to incorporate the HART standard into many of our existing 4-20mA instruments. The HART
based smart instruments would facilitate calibration and at the same time preserve our investment.
During 1996-97, DWSD developed and implemented a pilot-scale version of the AMR/SCADA system tomodernize the point-of-sale metering system. The pilot project was expanded (1999-2002) to a $10
million major infrastructure upgrade. Figure 2 illustrates a schematic diagram of DWSD’s AMR/SCADA
system. The AMR/SCADA system utilizes a packet radio network of personal computers, programmable
logic controllers (PLCs), and remote terminal units (RTUs). The system relies on the power of HART
communication to deliver consistent, reliable data on system performance.

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Figure 2. Schematic of DWSD’s AMR/SCADA system

The decision to adopt the HART standard for integrating our meters was relatively simple since wealready had in-house experience. Perhaps, more importantly, HART was evaluated to be the only stable
and reliable technology available at the time which would enable us to integrate a vast array of diverse
field devices and technologies including mechanical, venturi, orifice, magnetic and sonic meters into asingle digitally networked system.
Other field device technologies such as FOUNDATION™ fieldbus and Profibus-DP were still evolving,
costly, and radically different and incompatible with our existing smart instrumentation. Use of theseother technologies would have substantially increased the project risk and the total installed costs.
HART technology was an ideal fit for our requirements since it delivered the benefits of an all-digitalsystem at a minimized incremental investment for the modernization project. Most of our existing
instrumentation was HART-capable, which enabled us to use the existing wiring. The project easily
gained management approval mainly due to our ability to default back to the existing analog-chartrecorder system in case of difficulties.
Maintaining the Look and Feel of Mechanical Meters to Ease Transition
At the start of the pilot project, our technicians and customers indicated a strong preference formechanical meter-type totalizers at each metering site. To improve their comfort level with the159electronic instruments, we configured the LCD displays of the HART-based smart instruments to indicate
the current value of the measured variable, e.g., flow rate and/or totalized flow, which provided anemulation of the odometer-like registers of the mechanical meters. Figure 3 illustrates one such HARTbased smart instrument (manufactured by SMAR International) indicating measured flow rate. The LCD
alternates displaying the flow rate and totalized flow (not shown).

3

Figure 3. HART-based smart instrument indicating flow rate (PV measured in m /hr)

Unlocking the Power of HART to Reap Big Dividends
Most HART-based smart devices are capable of performing multiple functions in a single instrument.
Previously, we required multiple electrical devices for detecting the rate of flow, outputting a
proportional signal, integrating the proportional rate signal into a volume, and totalizing the volume.
Thus, by combining functions we were able to eliminate these old devices, as we selected HART-based
differential pressure transmitters that are capable of performing on-board, flow totalization and selfmonitoring for diagnostics. In addition, the HART data communications protocol provides the values to
the PLC/RTUs in binary bit streams that virtually eliminate signal transfer errors.
As a result of HART technology, we were able to distribute the totalization function to a lower, HARTenabled smart device level, instead of the traditional PLC/RTU device. This resulted in reducing the loadon the PLC/RTU, as well as eliminating the potential loss of data in case of a power loss. A schematic
diagram of an advanced metering system based on HART technology is illustrated in Figure 4.

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LEGEND:LEGEND:
Yellow = Differential Pressure Cells
Green = Pressure Transmitters
Purple = HART Data Communications on Instrument Loop
Pink = AC Power to Solenoid of 4-Way Cross-Over Valve
Gray = Actuator & 4-Way Cross-Over Valve
Orange = Limit Switches on Valve
Tan = RTU, Metricom Radio & DF/1 Data Communications
Dashed = Present in Some Meter Pits, or in Separate Pit

Above Ground Control Cabinet
Coax & Power Surge Suppressors,
Open Door Alarm, High Sump Alarm,
AC Power Fail Alarm, Strip Heaters

RADIO

File = Typical Meter.vds
Prepared by: Cliff Montgomery
Rhythm Technologies, LLC

PLC/RTU
Battery , Chargers& Power Supplies

Meter Pit

PT

DP

DP
PT

PT

PRV
Limit Switch

Actuator & Limit Switches,
Four-Way Valve with Solenoid

Sump &
Sump Pump

Figure 4. Schematic of a Venturi/Orifice meter based on HART technology
The flow totalization data is actually retained in the memory of each HART-enabled smart instrument
even when there is a loss of power. As a matter of fact, our system survived the massive power failure ofAugust 14, 2003 that occurred in the Northeastern part of the United States with little or no loss data.
This was an unrehearsed critical test since it occurred during our peak-revenue summer months.
As an additional benefit, by executing the totalization function at the HART device level, we were able toobtain much more accurate totalization data. The HART device integrates totalization data sampled far
more frequently than the PLC/RTU. As a result, the totalization values are more accurate.
The sampling frequency of the microprocessor based instrument approaches the Nyquist criteria for
integrating the fluctuations of the water flowing through venturis and orifices that can reach to audio
frequencies. The best of the communications protocols for instrumentation are substantially slower
resulting in random sampling errors that although small relative to instantaneous flow, accumulate in
the totalized flow far beyond acceptable limits.
With the need to read instantaneous flow for range switching combined with the necessity of totalizing
flow in the instrument, this project would have been far more costly without the HART ability to readmultiple functions in a single smart instrument. By shifting the calculations to the smart instruments, wefreed the PLC/RTU to perform other tasks, such as device monitoring for all HART devices located at theunderground metering facilities, and storing 31 days of metering data collected at 5-minute intervals.
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We were also able to maintain greater accuracy of metering data throughout our water-distribution
system, largely due to HART’s ability to preserve the full accuracy of the measuring element in a digitalformat. The improved accuracy has directly resulted in increased revenues, since our old mechanicalmeter based cash registers often erred in favor of our wholesale customers.
The need for having redundant metering systems has been eliminated since the same metering datareported from our HART-based instruments to the RTU, is “carbon copied” every five minutes directlyfrom the on-site RTU to DWSD as well as to our wholesale customers within a few seconds – weprovided a SCADA PC to each wholesale customer. This has already contributed to improved customer
satisfaction.
Our wholesale customers can access metering data received from their respective meters directly rather
than receiving it through our headquarters. This assures our wholesale customers that DWSD is not
adjusting or manipulating their metering data.
HART enables the master device such as the PLC/RTU to automatically query each smart instrument todetect the types and brands of HART-based instruments on the network. Instrument data such as theirbrand type and serial numbers are collected each day for a permanent record of each instrument. HART
enables the detection and documentation of instrument changes that invalidate calibration.
Metering data received from failed instruments is not logged or used in any billing computation.
Previously, a failed analog instrument sometimes produced bogus signals thereby corrupting the meterreadings.
HART-enabled remote monitoring, calibration, and validation of metering systems have contributed to
improved safety and greater customer satisfaction. Our technicians can now perform these tasks on
any HART-based smart device in the comfort of their office. For example, pause and resume signals canbe sent remotely to these instruments for series connected meters for range switching. With improved
diagnostics, our technicians can quickly detect and repair failures in our water distribution system.
Complaints about low water pressure have been virtually eliminated since a majority of thesecomplaints have been attributed to faulty regulating valves operated by our wholesale customers. Our
system now monitors these valves and reports any problems directly to the customers.
Safety has also been improved since the need to enter the OSHA regulated confined space of theunderground metering facilities for troubleshooting purposes has been greatly reduced or eliminated.
Previously, there have been fatal accidents in these underground metering facilities.
Metering data obtained from the HART-instrument is communicated and stored in digital form,
eliminating paper-based recordings. A digital packet radio network, which functions like a wirelessintranet, is used to “carbon copy” all metering data to redundant data historians and to SCADA PCs that
DWSD provided to each customer.

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The DWSD meter technicians use radio linked laptop computers for configuration and direct entry ofcalibration data, eliminating paper and copying errors. By analyzing the real-time and historical datacollected, we have improved efficiency by revising operating procedures.
HART has served us so well by utilizing all of our existing plant assets. Other fieldbus technologies havematured considerably since 1996, when DWSD began piloting our system. Nevertheless, we would stilluse HART, even if the project were starting today. Other newer fieldbus technologies would have cost us
at least twice as much, since we would have had to discard a majority of our existing instruments.
Looking ahead, DWSD is developing another SCADA system for controlling our treated watertransmission system and wastewater collection system, which includes new sewer meters. Since many
instruments included in the SCADA system are also HART-capable, we would like to tie them in into ourwater metering AMR/SCADA system.

2003 HART Plant of the Year163

MILWAUKEE SEWERAGE DISTRICT USES HART TO SUPPORTSAFER SEWER SYSTEMPROJECT OBJECTIVES•

Improve measurement by using temperature compensated devices and perform installation
calibration in an explosion-proof area.

SOLUTION•MMSD installed more than 200 level transmitters with HART-based interfaces in manholes,
which are Class 1, Division 1-rated areas. MMSD installed the HART instruments because thelevel instrumentation in place was not temperature compensated.

•

The HART dual functionality (analog plus digital) allows seamless operation of the system while
the instrument is being interrogated and updated.

RESULTS•

HART-enabled devices saved money for MMSD and those savings coupled with the technology’s
flexibility, reliability and field ruggedness are why HART devices are used throughout
Milwaukee’s sewage-treatment system.

•

The installation reduces the time to calibrate the instrument and eliminates the need to enter
the manhole

To keep its own process competitive, the Milwaukee Metropolitan Sewerage District (MMSD) installed
more than 200 level transmitters with HART-based interfaces in manholes, which are Class 1, Division 1rated areas. MMSD installed the HART instruments because the level instrumentation in place was nottemperature compensated.

HART technology’s analog functionality allowed an intrinsically safe barrier and installation calibration in
an explosion-proof area. “The collection-system manholes are typically entered once-a-year forcalibration checks,” explains Eugene Moe, senior instrumentation and control engineer for Earth Tech
Inc. in Sheboygan, Wisconsin. Earth Tech was part of a joint venture team hired to manage MMSD’soperations.

164

“The result is an installation that reduces the time to calibrate the instrument and eliminates the needto enter the manhole, unless the unit fails completely.”This analog functionality plus HART Protocol’s simultaneous digital functionality is important to Moe.
“It’s not critical that the signal and calibration be available at the same time,” he explains. “But the dual
functionality allows seamless operation of the system while the instrument is being interrogated andupdated.”Moe asserts that using HART-enabled devices saved money for MMSD and adds that those savings
coupled with the technology’s flexibility, reliability and field ruggedness are why HART devices are usedthroughout Milwaukee’s sewage-treatment system.

165

PERSIAN GULF COMPANY USES HART COMMUNICATION TO
IMPROVE WATER CONVERSION PROCESSPROJECT OBJECTIVES:•

Get better resolution and accuracy from measurement devices•

Save time and labor in calibration and troubleshooting.

•Achieve best functionality of asset management•

Obtain access to all instrument/device data

SOLUTION:•

Install more than 2,000 HART-enabled devices.

RESULTS:•

Saved time and labor in calibration and troubleshooting during pre-commissioning, startup andcommissioning.

•

Analog signal provided the fastest and best overall scan period•

Digital signal helped to quickly calibrate and troubleshoot devices including control valve
positioner feedback•

HART technology’s interoperability capability allowed integration of asset management systemand devices from different manufacturers•

Remote troubleshooting of device status reduced time needed to check devices in the field•

No disputes because HART is proven to be a very reliable platform

Saline Water Conversion Corporation (SWCC) used HART technology in a major re-instrumentation
project as the catalyst for improving asset management. “Despite the size of this mega project, HART
technology helped us at the core achieving best resolution and accuracy of the data,” says T. Veeresh
Prasad, Yokogawa Engineering.

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The Saline Water Conversion Corporation (SWCC) used HART technology in a major re-instrumentation
project as the catalyst for improving asset management. The company installed more than 2,000 HARTenabled devices in a facility in Jubail, Saudi Arabia, that houses six 60-megawatt power plants and adesalination plant. Water and electricity from the facility service both Jubail and the Saudi capital,
Riyadh.
“Despite the size of this mega project, HART Communication helped us at the core,” says T. Veeresh
Prasad, Yokogawa Engineering Asia System Integration Center, Singapore. “HART technology achievedbest resolution and accuracy of the data, compared to the old devices that were in place for the past 20plus years.” (The Al-Jubail Phase 1 plant was built on the Persian Gulf in 1982)
Installation of the new HART devices saved the company time and labor in calibration andtroubleshooting during pre-commissioning, startup and commissioning. HART technology’s
simultaneous analog and digital communications capability provided an additional benefit.
“Analog communications helped because of our fastest turnaround time requirements for achieving
best overall scan period,” Prasad says. Digital helped “to quickly calibrate, and to troubleshoot issues,
including control valve positioner feedback, etc.”
HART technology’s interoperability capability allowed SWCC to utilize the instrument asset management
system as part of turnkey total system integration and the field devices from different manufacturers
using HART-compatible I/O cards. “Best functionality of asset management is achieved, even though thehost system and the actual field devices aren’t from the same supplier,” Prasad says.

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HART-based HMIs provided greater accuracy and were used to calibrate most devices, adds Prasad. And,rather than running to the field to check devices’ troubleshooting status, the staff now uses the asset
management system to crosscheck that status.
“The result is less disputes—or no disputes,” Prasad says. “HART is a very reliable platform for fastest
response requirements of control and automation safety-instrumented systems. It competes with allother buses, all the time.”

168

SLUVAD WATER TREATMENT WORKS EMPLOYS HART
PROTOCOL’S MULTI-DROP NETWORK CAPABILITY FORFLEXIBILITY, REDUNDANCY, COST SAVINGSPROJECT OBJECTIVES•

Automate the water treatment plant for highest possible redundancy•

Renovate filter bed systems while safeguarding the integrity of the plant control system

SOLUTION•

92 networked HART-enabled instruments installed to control flow, level and pressure•

HART instruments connected using HART Protocol’s multi-drop networking capability•

Instruments connect to the DCS using 16-channel HART field modules to multiplex the signals

RESULTS•

Connecting up to four instruments on each multi-drop loop reduced cabling and system I/O
requirements nearly 75 percent for significant reduction in hardware and installation costs•

Highly modular design contributed significant engineering and commissioning savings; engineers
coded once, copied 28 times

Switching from hydraulic to electric valve actuation, HART Protocol’s multi-drop capability proves a time,
cost and hardware saver in networking 92 instruments

169

HART-based instrumentation was used in a major renovation of filter bed systems at the Sluvad Water
Treatment Works in South Wales. Water treatment contractor, Purac Ltd., used an innovative design torenovate the plant with HART-based instrumentation and to safeguard the integrity of the plant control
system.

NETWORKHART Multi-drop Network
According to Purac Senior Engineer Mark Cargill, the project objective was to automate the plant using
the most appropriate equipment for giving the highest possible redundancy. After careful evaluation,
Purac engineers based their project design on an all-digital HART multi-drop network solution thatoffered considerable hardware and installation cost savings over traditional 4-20mA and other available
options.
“There is such a wide range of HART-compatible products available for flow, level and pressure
applications that we found it offered the flexibility and performance we required at the best cost,”
Cargill says. “HART was an easy choice because it is a proven, cost-effective technology.”
The project replaced the hydraulically-operated filter bed valves with new electrically actuated valves,
and added new instrumentation and a new distributed control system (DCS) to provide full automatedcontrol of the entire facility. Because the plant had to stay operational during the refit, a modular design
approach with HART-compatible instruments in multi-drop network configurations proved to be theideal solution for each filter bed.
Twenty-eight rapid gravity filter beds were fitted with a total of 92 networked HART instruments tocontrol flow, level and pressure. All HART instruments are connected using the multi-drop networking
capability of the HART Protocol. The instruments are connected to the DCS system using 16-channel
HART field modules (HFM) to multiplex the signals.

170

Multi-drop Network with 2 & 4 wire Devices

In a novel architecture, one HFM channel is allocated to each filter bed. “If a problem occurs in any one
loop, only one filter is affected,” Cargill says. “The other 27 filter beds remain fully operational,
safeguarding the integrity of the plant control system.”
According to Cargill, with up to four instruments on each multi-drop loop, the cabling and system I/O
requirements were cut by nearly 75 percent, creating a significant reduction in both hardware andinstallation costs.
Significant savings in engineering and commissioning were also realized from the highly modular design.
System engineers had to develop the design and code only once then repeat it 28 times.

171

WIRELESSHART APPLICATIONSINDUSTRYCOMPANYLOCATION

SteelNorthstar Bluescope Steel

Ohio

173

EnergyProgress Energy

Various174

Chemical

BASF

Netherlands

176

172

PAGE #

WIRELESSHART NETWORK HELPS STEEL MILL INCREASE
PRODUCTION AND REDUCE COSTS
Replacing a traditional wired network with a WirelessHART-based network for control and monitoring
has helped Northstar Bluescope Steel improve operations and worker safety in a harsh environment at
its mini-mill in Delta, Ohio. By improving furnace control, the mill has increased production by as muchas one batch per day (with each batch worth as much as $200,000), cut maintenance costs (by $200,000
annually), and improve worker safety.
The self-organizing WirelessHART network collects data used to control the temperature of coolingpanels and water-cooled burners on the mill’s electric arc furnace. This data is critical to safe furnace
operation. Overheating cooling panels can lead to major furnace damage, with a blown-out panel
costing as much as $20,000 to repair. Production time is also lost when the furnace must be shut down
during maintenance or repairs.
The steel mill replaced a hard-wired monitoring network with hundreds of wiring junctions that sufferedfrequent measurement failures in the mill's harsh environment, with its high electromagnetic field,
flying slag, vibration, moisture, and temperatures as high as 3,000 degrees Fahrenheit.
“Between nine and 12 measurements per week would fail due to high temperatures or physical damage
to sensors, cable or conduit," says Kearney. "And when a measurement point fails, the furnace must be
shut down. The new wireless solution eliminated almost 100% of the cable and conduit – which reduced
maintenance costs by $200,000 annually.”
The Emerson® Smart Wireless network includes 32 Rosemount® WirelessHART temperature transmitters;
28 for control and four for monitoring. The transmitters send their data to an Emerson gateway, whichinterfaces with the mill’s transformer-regulation and burner-control system.
“Safety has also been improved,” Kearney said. “The furnace’s cooling panels are operating consistently
at a safe temperature, and there is less maintenance required around the hot furnace shell, where
ambient temperatures can be 140 degrees.”

173

ELECTRIC UTILITY USES WIRELESSHART COMMUNICATION TO
IMPROVE PERFORMANCE EFFICIENCY
Progress Energy, a publicly-owned U.S. electric utility, uses WirelessHART communication to improve
performance efficiency and output in multiple plant locations. The company keeps plant equipment andsystems running smoothly using HART technology for testing, troubleshooting, and verifying
performance standards on new and upgraded equipment.
Progress Energy maintains 240 temperature and pressure transmitters and some flow devices at 32
plant locations. Previously, these devices had been hardwired to HART multiplexers to accommodate
far-flung cable runs from one site to the next across facilities and even over streets, to conduct tests.
With the introduction of the WirelessHART standard and the availability of network WirelessHART
adapters that conform to the standard, the company sought to replace its aging test equipment andstreamline testing with a new wireless system. Dick Fletcher, Progress Energy’s Performance TestingGroup team manager, notes that the company had a major investment in existing HART smart
transmitters. “The logical thing to do was get a common data acquisition system to be shared across thesystem by performance testing,” he says. “A system that could handle a variety of instruments, interface
with standard commercial instruments using standard protocols and be easy to configure.”
Project objectives“We had to get the best bang for the buck,” says Fletcher, “and that meant that we had to maintaincompatibility with our existing investment in HART-enabled transmitters.”
The goals were todevelop a common field data acquisition system; allow equipment sharing across the system andminimize the total company inventory; take advantage of HART’s ability to collect data digitally and in
multi-drop mode; ease the installation of the test equipment to minimize time and effort, and benefit
from a flexible, easily expandable and easily configurable system.
Using recently developed HART-based products, like the MACTek Bullet which supports up to eight HART
transmitters in field-proven HART multi-drop mode, meant a wireless gateway could replace failing
multiplexers, and far fewer cables would need to be deployed for temporary test transmitter
installations.
“The economics of a hybrid wireless-wired HART system became more feasible for us to consider. Whilewe were able to show no connection to the plant’s cyber assets, we were impressed with the security ofthe encrypted HART protocol,” says Fletcher, who did have one caveat to using the wireless network
adapters. Because WirelessHART technology uses the same 2.4-GHz frequency band as Wi-Fi, he wasconcerned about range limits and the possibility of interference between objects and antennas.
However, in actual use, the HART instruments don’t have to be in line-of-sight to establish a network174

and, Fletcher notes, “the WirelessHART radio links will form in circumstances that Wi-Fi couldn’t hope toachieve, and they just work. Wi-Fi was designed for speed, while WirelessHART is designed for datareliability.”
Benefits Realized
The advantages of the new system were apparent, from up-front cost to the long-term reliability of thedata acquisition system and, in turn, the reliability of assets across Progress Energy’s 32 plants. Labor
savings were evident from the group’s first outing with the new system.
“I estimate that we saved 100-150 man-hours,” says Fletcher. “On a small test, we saved about six manhours on a setup that took about 10 man-hours to set up using wireless. With an average of 15 tests a
year and saving an average 33 hours of labor each, that works out to $20,000 savings per year.”Beyond up-front savings, the new system reduces cabling, as the radio links eliminate situations thatplaced cables at risk of damage. “Along with the streamlined process for data acquisition, we get abetter picture in real time of how our test equipment is performing and communicating,” says Fletcher.
While HART is a hybrid analog/digital specification, wireless data transmission is all-digital. This allows
HART technology to transcend its heritage as a diagnostic tool and enter the world of digital bus
functionality. Fletcher notes the protocol is built for redundancy and reliability.
In wireless multi-drop mode, the analog signal isn’t used; instruments use the 4-20 mA signals for
power, but process variables, from tags to diagnostics and process variable measurements, aretransmitted digitally. So, in a sense, the technology might open the door for new applications previously
thought to be the sole domain of digital fieldbus networks, such as condition monitoring and asset
management.

175

WIRELESSHART AT BASF
Challenging Applications in the Production ofHigh-Quality Catalysts

BASF located in De Meern, the Netherlands

Vacuum dryers for the drying process

In the process industry there is a growing interest in wireless data communication – not for standard
connections but for applications where wires cause obstruction. Despite the level of interest, potential
users are concerned about data loss, security, or incorrect data transfer. BASF in De Meern has
experience with a number of wireless applications.
The plant produces high-quality catalysts (chemical process accelerators) for the process industry, which
are used in the chemical, petrochemical, food and pharmaceuticals industry. An example from the foodindustry is hydrogenation of soya oil to optimize its melting point and storage life for use in margarines
or dressings. Other applications include the desulphurization of waste gases and oil, the manufacture ofplastics and the conversion of gas into liquid fuels. These processes involve a number of systemcomponents for which wireless communication would be a good solution.
Company profile
BASF is one of the world’s leading chemical companies. With about 105,000 employees, six verbund
sites and close to 385 production sites worldwide they serve customers and partners in almost all
countries of the world.
Procedure
When catalysts are being produced the product goes through a number of steps. One of the steps is thedrying process, which takes place in a large vacuum dryer. This is a ton in the form of two cones
connected at the base, with a diameter of approximately two meters. The product, a powder, can be fed
in from the top through the tip of the cone in which a manual valve is mounted. On the other side, thetip of the other cone, there is an access point for taking samples.

176

The vessel is suspended from two points on each side of the connecting surface between the two cones.
The vessel revolves around these points, ensuring that the product is mixed well with a special liquid
injected through one of the rotation points.
This liquid forms a coating around the powder grains. The product must then be thoroughly vacuumdried. The final product is tipped out of the vessel via the same valve.
Samples must be taken regularly during the process to assess how dry the product is. For this purposethe rotating drum is stopped and the operator takes a sample through the special access valve. The
sample is then analyzed in the lab. This operation takes between 30 to 45 minutes. Sometimes as manyas three samples are taken. When the product is sufficiently dry, the process can be stopped and the
product tipped out. The total drying process takes approximately eight hours. For certain types of
product it can take 10 to 12 hours.
“We went in search of alternatives so that we could dispense with the time-consuming sampling process
and free-up the operators. On the Endress+Hauser stand at a trade fair, we saw a demonstration of awireless system for measuring temperature. The system used standard transmitters and a module-withantenna was used to transmit the data signal to a host by means of WirelessHART. For us, this was
obviously an excellent solution.” - Ferry Stofberg and Ramon Kranendonk / BASF
Scope of supply
•
•
•
•
•
•

Quick scan, system integration and engineering
HART field devices
WirelessHART Gateway and Adapter
FieldCare Plant Asset Management
Commissioning and startup
Training and instruction

System overview
After the technical solution had been delivered by Endress+Hauser, the BASF engineers looked for
additional possibilities. The temperature course is the primary variable for determining the moisture
content of the product. In addition, the pressure in the drum is of interest. Therefore two transmitterswere fitted, one for pressure and one for temperature. The product in the drum is fairly aggressive,
which means special materials were required for the thermowell and chemical seal.
Another criterion was the straightforward integration in the existing system. Control is via Siemens PLCs
and PROFIBUS.
FieldCare software is used for maintenance. The gateway has a 24V feed and two outputs, Modbus andEthernet. The Modbus signal was converted to PROFIBUS DP for communication with a Siemens PLC.
Endress+Hauser provided the essential programming. The connection to FieldCare was via Ethernet.

177

Diagram of the wireless connections
The WirelessHART adapters, which also supply power, are mounted directly on the transmitters. Two
additional adapters transmit the HART information from the instruments on the continuously rotating
drum to the gateway. Experiments are still ongoing, but have already revealed the
P-transmitter uses more energy than the T-transmitter.
Longer intervals (e.g. two minutes) between measurements have already produced an excellent saving.
Another idea would be to switch the transmitter on and off when required using WirelessHART
commands.
The expectation is that, before long, the process can be fully automated, which would result in an
impressive time saving and improvement in product quality. At that point, two other drums will also be
fitted with the new wireless measuring stations.
“BASF has a number of good applications for wireless communication and, thanks to the support ofEndress+Hauser, we are putting them to good use. We won’t be converting other existing parts of thesystem to wireless, mainly because of the short distances (max. 40 meters). For our factory, wired
connections are not a significant cost factor.” - Ramon Kranendonk / BASF

178

Vacuum dryer in vertical position

Customer benefits••••

Cost savings on installation and assemblySignificant reduction of energy and laboratory costs throughincreased efficiency
Improved process control and product quality
Improved availability through condition-based maintenance strategy and centralized
device performance monitoring179

WHERE TO GET INFORMATION
www.hartcomm.org
Main Office:

HART Communication Foundation
9390 Research Blvd., Suite I-350
Austin TX 78759 USA
Tel: 512-794-0369
Fax: 512-794-3904

Europe Office:

HART Communication Foundation - Europe
Contact: Jean-Luc Griessmann
Dornacherstrasse 210
CH-4053 Basel Switzerland
Tel: +41 61 333 22 75
Fax: +41 61 333 22 77

China Office:

HART Communication Foundation - China
Contact: Wu Minhui
No. 243 Daxue Road, Room 703
Yangpu District, Shanghai 200433
P.R. China
Tel: +86 18916590360

Japan Office:

HART Communication Foundation - Japan
Contact: Kaoru Sonoda
1-31-10 Shin-machi
Ome, Tokyo 1980024 Japan
Tel: +81-50-5539-9507

180

APPENDIX A: HART CHECKLISTHART HOST SYSTEM CAPABILITIES CHECKLIST
Date:_________________

Manufacturer:
Model number/name:
Revision or version:
Product application (configurator, DCS, RTU, etc.):
Function

Commands/Notes

Support Provided

How many HART I/O channels per card?
Can the system power the devices withan internal power supply?

 Yes  No

Which HART revisions are supported?

 Rev 3  Rev 4  Rev 5

Is burst modechannels?

supportedon Yes  Noall

Is multi-drop networking supported on all
channels?

 Yes  No

If yes, how many devices can be placedon a single network?

# of devices: _____________
 Hard coded

How are device-specific functions andfeatures supported?

 HART DDL binary files
 HART DDL source files
 Application resource files
 Other: ________________
 Device-specific features are not supported.

Indicate the parameters thataccessed in ANY HART device.

are

181

Manufacturer’s identification0 Re a dDis pla y te xtDisplay code

Function

Commands/Notes

Support Provided

Device identification (device type code)0 Re a dDis pla y te xtDis pla y code

Device identification (unique ID)

0 Re a d Dis pla y te xt

Device serial number0 Re a d Dis pla y te xt

Revision levels0 Re a d Dis pla y text

TAG

13, 18

 Re a d W rite

DESCRIPTOR

13, 18

 Re a d W rite

MESSAGE12, 17

 Re a d W rite

DATE

13, 18

 Re a d W rite

Upper-range value

15, 35

 Re a d W rite

Lower-range value

15, 35

 Re a d  W rite

Sensor limits

14

 Re a d

Alarm selection15

 ReadWrite-protect status

15

 Re a d

Analog reading

1, 2, 3

 Re a dPrimary variable

1, 3 Re a dSecondary variable3 Re a d

Tertiary variable3 Re a d

Fourth variable3 Re a dChange engineering units

44 Re a d W rite

Damping value

15, 34

 Re a d Write Re a d

Read device variables How many? (u 33
to 250)182

Materials of construction

Device specific Re a d W rite

HART status information (change flag,
malfunction, etc.)

Standard status bits

 Re a dDis pla y te xtDis pla y code

Device-specific status information48

 Re a dDis pla y te xtDis pla y code

Use of status bits in control logic?

Std & 48

 Ye s No

Use of status bits in alarm handling?

Std & 48

 Ye s No

Set point (PID and output devices)
Which devices?

Device specificRead

Support of device-specific commands/
functions:(a) for your own company’s fielddevices Ye s No Ye s No(b) for other vendors’ field devices
Rezero43

 Ye s No

Loop test (fix the analog current at
specified value)40

 Ye s  No

 Ye s No

Support calibration procedures?
Which products?
Calibrate the D/A converter

45, 46

 Ye s No

Initiate device test41

 Ye s No

Clears configuration flag?

38

 Ye s Novariable50, 51

 Ye s No

Support for devices with multiple analog
outputs

6070

 Ye s No

Set polling address

6

 Yes  No

Text messages provided on commanderror responsesAll Ye s No

Read/Write
assignments?

dynamic

 Ye s No

OPC Client183

 W rite Ye s No

OPC Server
HART Command Pass-throughSome systems have the ability to act as a conduit or router between a software application running on a separate
platform and a HART field device. In effect, this ability gives the end user the functionality provided both by thesystem and by the application.
 Ye s No

Is pass-through supported?

184

APPENDIX B: HART FIELD CONTROL
HART Transmitter with PID Control Installation
The HART transmitter with PID control (Fig 21) is wired in series with the field device (valve positioner orother actuator). In some cases, a bypass capacitor may be required across the terminals of the valve
positioner to keep the positioner’s series impedance below the 100 Ω level required by HART
specifications. Communication with the HART transmitter requires the communicating device (handheld
terminal or PC) to be connected across a loop impedance of at least 230 Ω. Communication is notpossible across the terminals of the valve positioner because of its low impedance (100 Ω). Instead, thecommunicating device must be connected across the transmitter or the current sense resistor.

Figure 21 – HART Transmitter with PID Control Wired in Series

185

It is also possible to use both a smart transmitter and a smart valve positioner in the loop. The control
function can be in either device. The HART Protocol allows one low-impedance device on the network,
which is typically the current sense resistor. In Figure 22, the smart valve positioner is the lowimpedance device, which eliminates the need for a current sense resistor. Communication is possible byconnection across the terminal of either the transmitter or the positioner.

Figure 22 – Field Control in Transmitter or Positioner

186

APPENDIX C: TECHNICAL INFORMATION
Communication Signals
Type of Communication

SignalTraditional analog

4–20 mA

Digital

FSK, based on the Bell 202
telephonecommunication
standard

Logical “0” frequency

2,200 Hz

Logical “1” frequency

1,200 Hz

Data Information
Data update rate:
Request/response mode—2-3 updates per second
Optional burst mode—3-4 updates per second
Data byte structure:
1 start bit, 8 data bits, 1 odd parity bit, 1 stop bit
Data integrity:
Two-dimensional error checking
Status information in every reply message
Simple Command Structure
Type of Command

Structure

Universal

Common to all devices

Common practice

Optional; used by many devices

Device specific

For unique product features

187

Communication Masters
Two communication masters
Variables
Up to 256 variables per device
IEEE 754 floating point format (32 bits) with engineering units
Wiring Topologies
Point-to-point—simultaneous analog and digital
Point-to-point—digital only
Multi-drop network—digital only (up to 15 devices)
Cable Lengths
Maximum twisted-pair length—10,000 ft (3,048 m)
Maximum multiple twisted-pair length—5,000 ft (1,524 m)
Cable length depends on the characteristics of individual products and cables.

188

GLOSSARY
Bell 202
A U.S. telephone standard that uses 1,200 Hz and 2,200 Hz as 1 and 0, respectively, at 1,200 baud. A full
duplex communication standard using a different pair of frequencies for its reverse channel. HART uses
Bell 202 signals but is a half-duplex system, so the reverse channel frequencies are not used.
Burst (Broadcast) ModeA HART communication mode in which a master device instructs a slave device to continuously
broadcast a standard HART reply message (e.g., value of a process variable) until the master instructs it
to stop bursting
Cable Capacitance per Unit of Length
The capacitance from one conductor to all other conductors (including the shield if present) in the
network; measured in feet or meters
Cable Resistance per Unit of Length
The resistance for a single wire; measured in feet or meters
Closed-Loop Control
A system in which no operator intervention is necessary for process control
Communication Rate
The rate at which data are sent from a slave device to a master device; usually expressed in data
updates per second
DCS
See Distributed Control System.
Distributed Control System
Instrumentation (input/output devices, control devices, and operator interface devices) that permits
transmission of control, measurement, and operating information to and from user-specified locations,connected by a communication link
EDD/DD
See Device Description.
EDDL/DDL
See Device Description Language.
189

Electronic Device Description
A program file written in the HART Device Description Language (DDL) that contains an electronic
description of all of a device’s parameters and functions needed by a host application to communicate
with the device
Electronic Device Description Language
A standardized programming language used to write DDs for HART-compatible field devices
Field
The area of a process plant outside the control room where measurements are made, and to and fromwhich communication is provided; a part of a message devoted to a particular function (e.g., the address
field or the command field)
Field Device
A device generally not found in the control room; field devices may generate or receive an analog signal
in addition to the HART digital communication signal
Frequency Shift Keying
Method of modulating digital information for transmission over paths with poor propagation
characteristics; can be transmitted successfully over telephone systems
FSK
See Frequency Shift Keying.
Gateway
A network device that enables other devices on the network to communicate with a second network
using a different protocol
HART Command Set
A series of commands that provide uniform and consistent communication for all master and slave
devices; includes Universal, Common Practice, and Device-Specific commands
HART Communication Protocol
Highway Addressable Remote Transducer communication protocol; the industry standard protocol for
digitally enhanced 4-20 mA communication with smart field devices
HART Handheld Communicator
A handheld master device that uses the HART Communication Protocol and DDL to configure orcommunicate with any HART device

190

HART Loop
A communication network in which the master and slave devices are HART compatible
Host Application
A software program used by the control center to translate information received from field devices into
a format that can be used by the operator
Interoperability
The ability to operate multiple devices in the same system, independent of manufacturer, without lossof functionality
Intrinsic Safety
A certification method for use of electrical equipment in hazardous (e.g., flammable) environments; atype of protection in which a portion of an electrical system contains only intrinsically safe equipmentthat is incapable of causing ignition in the surrounding environment
Intrinsic Safety Barrier
A network or device designed to limit the amount of energy available to the protected circuit in ahazardous locationIS
See Intrinsic Safety.
Master Device
A device in a master-slave system that initiates all transactions and commands (e.g., central controller)
Master-Slave Protocol
Communication system in which all transactions are initiated by a master device and are received andresponded to by a slave device
Miscellaneous Series Impedance
The summation of the maximum impedance (500 Hz–10 kHz) of all devices connected in series between
two communicating devices; a typical non-intrinsically safe loop will have no miscellaneous series
impedance
Modem
Modulator/demodulator used to convert HART signals to RS232 signals

191

Multi-drop Network
HART communication system that allows more than two devices to be connected together on a single
cable; usually refers to a network with more than one slave device
Multimaster
Refers to a communication system that has more than one master device. The HART Protocol is a simple
multimaster system allowing two masters; after receiving a message from a slave device, the masterwaits for a short time before beginning another transmission, which gives the second master time toinitiate a message
Multiplexer
A device that connects to several HART loops and allows communication to and from a host application
Multivariable Instrument
A field device that can measure or calculate more than one process parameter (e.g., flow andtemperature)
Network
A series of field and control devices connected together through a communication medium
Parallel Device Capacitance
The summation of the capacitance values of all connected devices in a network
Parallel Device Resistance
The parallel combination of the resistance values of all connected devices in the network; typically,
there is only one low-impedance device in the network, which dominates the parallel device-resistancevalue
Pass-throughA feature of some systems that allows HART Protocol send-and-receive messages to be communicatedthrough the system interface
PID
Proportional-integral-derivative
PID Control
Proportional-plus-integral-plus-derivative control; used in processes where the controlled variable isaffected by long lag times

192

Point-to-Point
A HART Protocol communication mode that uses the conventional 4-20 mA signal for analog
transmission, while measurement, adjustment, and equipment data are transferred digitally; only two
communicating devices are connected together
Polling
A method of sequentially observing each field device on a network to determine if the device is ready tosend data
Polling Address
Every HART device has a polling address; address 0 is used for point-to-point networks; addresses 1-15
are used in multi-drop networks
Process Variable
A process parameter that is being measured or controlled (e.g., level, flow, temperature, mass, density,
etc.)
Protocol
A set of rules to be used in generating or receiving a message
PV
See Process Variable.
Remote Terminal Unit
A self-contained control unit that is part of a SCADA system
RTU
See Remote Terminal Unit.
SCADA
See Supervisory Control and Data Acquisition.
Slave Device
A device (e.g., transmitter or valve) in a master-slave system that receives commands from a masterdevice; a slave device cannot initiate a transaction
Smart Instrumentation
Microprocessor-based instrumentation that can be programmed, has memory, is capable of performing
calculations and self-diagnostics and reporting faults, and can be communicated with from a remotelocation
193

Supervisory Control and Data Acquisition
A control system using communications such as phone lines, microwaves, radios, or satellites to link
RTUs with a central control system
Zener
Type of shunt-diode barrier that uses a high-quality safety ground connection to bypass excess energy

194