Ethernet –To the Field

Ethernet-APL™. Ease of adoption. Seamless integration.
Simplified installation. Greater range. Valuable data.

01

Abstract
Process plants operate for 20+ years and are required to be safe for people, the product,
and the environment. Explosion potential in hazardous areas and harsh conditions requirethat any deployment of new technology is both thoroughly tested and provides added
business benefits. Technology must not be complicated in handling or require extensive
training. Ethernet is the de-facto communication standard in enterprises, but it does notmeet the requirements in the field of process automation without modification.
Ethernet with an Advanced Physical Layer (Ethernet-APL™) will enable long cable lengths
and explosion protection via intrinsic safety with communication and power over two wires.
Based on IEEE and IEC standards, Ethernet-APL supports any Ethernet-based automation
protocol and will develop into a single, long-term stable technology for the entire process
automation community. This white paper covers the business environment, technical specifications, implications for different user types, and the development status of Ethernet-APL.

Situation and Business
Environment for Process
Applications
Process plants today compete to produce more products with less waste, and thin profit
margins require increased output yield with increasing quality. Digital transformation has
made it increasingly worthwhile for companies to consider making investments to obtain
more plant data from process automation systems and instrumentation. However, to do so,
new procedures and products are required to gain access to this data from every part ofthe plant and to extract more value on every production run.
In the manufacturing industries, the Industrial Internet of Things (IIoT) and Industrie 4.0 are
already part of everyday operations, and in the near future, these technologies will also
enter the field of process automation and instrumentation. In the process industries, domainspecific concepts like the NAMUR Open Architecture (NOA) or the Open Process Automation Standards (O-PAS™) by the Open Process Automation Forum (OPAF) are presently
attempting to simplify the efficient construction, commissioning, and operation of process
plants. Broader use of wireless solutions, simplified field device integration, and Ethernet tothe field represent integral components of these concepts.
Leading suppliers to process automation recognize the need from their customers to add
the universality and communication speed of standard Ethernet to existing field device installations. Ethernet has been deployed at the upper levels of the automation pyramid andin the field with 4-wire Ethernet devices, such as drives, flow, analyzers and motor control
centers. However, it requires enhancements to support applications in the field of process
plants. Figure 1 compares attributes of technologies connecting the field of process automation.

02

A key group of these leading suppliers and standards development organizations have cometogether with the goal of accelerating development and adopting a new open standard for
an Ethernet physical layer for the use in process automation and instrumentation that can be
deployed in hazardous areas, allow long-reach connectivity, and include an option for device
power over the line. This new Ethernet advanced physical layer, called “Ethernet-APL,”
together with the automation protocols that define the structure and meaning of information
being transmitted to and from field devices, will be one of the key enabling factors of the
IIoT in process automation. It will provide a vital prerequisite to extend the digitized world toprocess automation and instrumentation.
This paper describes the standardization and development of Ethernet-APL: a single, ruggedized and reliable physical layer with attributes that meet the requirements for the field ofprocess plants. Ethernet-APL enables a logical extension of Ethernet-based communications
from enterprise systems to the field. This last meter of Ethernet connectivity would allow any
enterprise boardroom to obtain data from all regions of its extensive network.

Past

Present

Pneumatic

Electronic + Fieldbus

Ethernet

Technology

Pneumatic

4 – 20 mA

4 – 20 mA+ HART

Fieldbus

Ethernet

Media

Air

AnalogAnalog+ serial

Serialdigital

Network

Measurement

1 value

1 value

1 + n values

n values

n values

Local accessto data––

GatewayrequiredIntegrated

Integrated

Gatewayrequired

GatewayrequiredIntegrated

Remote accessto dataFigure 1: Technologies for the field of process automation

03

Organization of
the Cooperation
The agreement to develop the Ethernet-APL technology under “The APL Project” was estab­lished in 2018 and is backed by the leading industry standard development organizations(SDOs) FieldComm Group, ODVA, OPC Foundation, and PROFIBUS & PROFINET International,
as well as by major industry suppliers of process automation, including ABB, Emerson,
Endress+Hauser, Krohne, Pepperl+Fuchs, Phoenix Contact, R. Stahl, Rockwell Automation,
Samson, Siemens, Vega, and Yokogawa.

Figure 2: Industry partners and associations of The APL Project04

The main objective of the cooperation is the specification of one single physical layer thatmeets the requirements of process automation. To achieve this goal, representatives ofproject members have been working on enhancements of IEEE and IEC standards underlying
the technology, have been collaborating on the development of a port profile to fit the
specific requirements of the process industries, and are participating in working groups tocreate or enhance the SDO’s relevant specifications and guideline documents. The finalization of all these standards and specifications makes this technology accessible to all users
and vendors.
With the cooperation of large companies and the most important SDOs in process automation,
as well as being based on existing and widely used standards, strong market adoption of thesingle physical layer “Ethernet-APL” is expected.

Technology for
Ethernet to the Fieldof Process Plants
Ethernet is a broadly accepted standard for wired digital communications that is standardized in IEEE 802.3. Its wide acceptance in industries and households created an eco-systemof standardized tools for installation, troubleshooting, and diagnostics.
This provides efficiencies in practice such as:
Low network configuration efforts
Same tool sets for troubleshooting and fault finding in OT and IT
Low installation efforts
However, Ethernet’s physical layers today do not address and fulfill the specific needs resulting from the harsh environmental conditions in the field of process plants. To be suitable forprocess plants, an Ethernet physical layer needs to meet the following criteria:
Two-wire cableLong cable runs
Power and communication on the same cable
Support of all explosion protection techniques incl. intrinsic safety
Simple installation technology
Potential reuse of existing fieldbus cable type ‘A’, which reduces cost and provides
easy migration strategies from fieldbus to Ethernet-APL
Resilience to electro-magnetic interference
Support of surge protection05

Ethernet-APL is an enhanced physical layer for single-pair Ethernet (SPE) based on 10BASET1L as shown in Figure 3. It communicates via a cable length of up to 1000 m at 10 MBit/s,
full-duplex, which is more than 300 times faster than current technologies, such as HART or
fieldbus. It is the logical extension for Ethernet and provides the attributes required for reliable
operation in the field of a process plant. Ethernet-APL is a physical layer that will be able tosupport EtherNet/IP, HART-IP, OPC-UA, PROFINET, or any other higher-level protocol.

Speed (M…GBit/s)
Ethernet Type2.5/5/10 GBit/s*** BASE-T1
Cable Type1 GBit/s
1000BASE-T1

Shielded
Unshielded

100 MBit/s
100 BASE-T1
10 MBit/s
10 BASE-T1S

Ethernet-APL based on 10BASE-T1L with provisions
for process industries defined in IEC Standards

10 MBit/s
10 BASE-T1L
10

15

40

100

1000
Cable Length (m)Figure 3: Ethernet-APL and Types of Single-Pair Ethernet defined in IEEE 802.3

Standardization forLong-Term Stability
Communications are based on 10BASE-T1L as defined in IEEE Std 802.3cg-2019, which is being
adopted by suppliers serving many market segments in building and industrial automation.
This significant market size enables manufacturers of semiconductors to provide chips in ahigh volume, contributing to a long-term, stable technology and platform, which can be integrated seamlessly into existing devices or instrumentation.
Ethernet-APL includes additional attributes required by process applications. The requirements result from outdoor installations and explosion hazardous area protection beyond
the long cable lengths. The additional electrical features follow respective IEC standards andprovide interoperability and simplicity in application.

06

stands for 2-Wire Intrinsically Safe Ethernet. This IEC technical specification,
1 2-WISE
IEC TS 60079-47 (2-WISE) defines intrinsic safety protection for all hazardous Zones
and Divisions. For users, this includes simple steps for verification of intrinsic safety
without calculations.

APL Project” creates the concept of Ethernet-APL by defining port profiles for2 “Themultiple power levels with and without explosion hazardous area protection. Markings
on devices and instrumentation indicate power level and function as sourcing or
sinking. This provides a simple framework for interoperability from engineering tooperation and maintenance.

allows wiring to screw-type or spring-clamp terminals, thus supporting
3 Ethernet-APL
cable entry through glands. Additionally, well-defined connector technology ensures
simplicity during installation work.

Components & Topologies
Ethernet-APL is designed to support various installation topologies, with optional redundancy
or resiliency concepts and trunk-and-spur. Ethernet-APL explicitly specifies point-to-pointconnections only with each connection between communications partners constituting a“segment”. Ethernet-APL switches thus isolate communications between segments. Thiseliminates disturbances such as cross talk and natively protects communications from device
faults on a different segment.
Ethernet-APL defines two general types of segments:
The “Trunk” provides high power and signal levels for long cable lengths of up to 1000 m.
The “Spur” carries lower power with optional intrinsic safety for lengths of up to 200 m.
Port profiles specify levels for power and communication signals, ensuring interoperability.
Ports can be classified as:
P = Powered, power source
L = Load, power drain
C = Cascade, for daisy chain configurations
U = Unpowered07

Table 1: Shows all technical attributes applicable to Ethernet-APL
Parameter

Specification

Standards

IEEE 802.3cg-2019 (10BASE-T1L), IEC 60079, IEC 61158

Power supply output

Up to 60 W, on APL Trunk

Switched network

Yes

Redundant cable andswitches

Optional

Reference cable type

IEC 61158-2, Type A (100 ohms resistance, +/- 20 ohms tolerance)
for intrinsic safety

Cable cross section

0,324 … 2,5 mm2 / AWG 26-14

Maximum trunk length

1000 m / into Zone 1, Div. 2

Maximum spur length

200 m / into Zone 0, Div. 1

Communications speed

10 MBit/s, full-duplex

Hazardous area protection:

For all zones and divisions.
Inspired by fieldbus with optional intrinsic safety at the device.

Figure 4 and Figure 5 illustrate the flexibility of topology choices for compact layouts andfor plants requiring long cable runs.
Two typical types of switches enable full flexibility of topologies:
power switch feeds power and communication into one or more trunk ports.
1 The
It is typically externally powered.
field switch provides at least one port to which a spur can be connected.
2 The
It can be powered via the Ethernet-APL trunk or externally.

08

Engineering

Asset Management

Controller

APL Field Switch

Auxiliary Power

Other Applications

Zone 2/Div. 2
Zone 1/Div. 2
Zone 0/Div. 1

Facility Ethernet
Ethernet-APL with
Intrinsic Safety Option

Figure 4: Example topology for a compact star installation

Engineering

Auxiliary Power

Asset Management

Controller

APL Power Switch

Other Applications

Zone 2/Div. 2
APL Field Switch

Trunk up to 1000m

Zone 1/Div. 2

Zone 0/Div. 1

Spur up to 200m

Facility Ethernet
Ethernet-APL with
Increased Safety
Ethernet-APL with
Intrinsic Safety Option

Figure 5: Example topology for long cable reach with up to 1000 m between switches on the trunk09

Scalability & Redundancy
A managed switched network architecture, a power budget of up to 60 W, and data traffic
at 10 Mbit/s provide for excellent scalability with regards to the number of Ethernet-APL
switches and instruments that can be connected. Additionally, Ethernet-APL transports andenables the functions from higher levels of the ISO-OSI model. These higher-level functions
fulfill the general requirements for simplicity, convenience, and automation of the network
itself, which users generally expect from Ethernet-based communication. These include:neighborhood detection at the switch that provides the means for
1 Automatic
simple device exchange.
communications paths that can run in parallel. Users gain complete access2 Multiple
to field instruments for asset management and dashboards in parallel and without
interfering with process automation communications.

redundancy or resiliency concepts at the network layer re-route communications
3 Ringin the case that an Ethernet-APL trunk segment fails for superior plant availability.
Ethernet-APL provides a single and highly ruggedized version for Ethernet that is fit forprocess plants. It provides the best possible simplicity in handling of all aspects with digitalcommunications in the field.

Handling & Installation
All connection choices standardized for Ethernet-APL are proven in use and well-known:
Spring-clamp terminals
Screw-type terminals
M8 and M12 connectors
The simple two-wire cable, with shielding, requires just a screwdriver to ensure connectivity,
and the related wire preparation tools to physically connect to the rest of the automation
installation. Ethernet-APL specifies fieldbus cable type A (100 ohms resistance, +/- 20 ohms
tolerance), IEC 61158-2 as reference cable of AWG classes 26 – 14, wiring cross section of
0,324 … 2,5 mm2. This provides easy migration strategies for existing fieldbus installations,
including support for intrinsic safety. Ethernet- APL prescribes polarity independence,
reducing wiring errors during installation.

10

Inherent diagnostics of an Ethernet-based system can be easily utilized to determine net­
work robustness, detect signal strength, and identify possible installation issues. Working
in tandem with operational staff in the control room, the maintenance and engineering teamcan easily and quickly install, replace, re-connect and commission any device. Installation
guidelines from the standard development organizations provide details and guidance fortechnicians and electricians. The installation guides cover the planning and selection ofcable types, cable lengths and parameters to be considered. Like all Ethernet-based technologies, numerous software and hardware tools exist to monitor, verify, and test systembehavior throughout the lifespan of the installation.

Adoption of Ethernet-APL
Ethernet has proven itself as a reliable communications technology in an environment withstrong requirements for interoperability. This is true for industrial industries, office buildings,
and many private homes. High standardization of Ethernet technology causes a largely
accepted environment with tools that range from product development and protocol stacks
to network planning, commissioning, and troubleshooting. The seamless implementation will
ensure fast adoption, high involvement, and thus a long-term business environment for allparties in the life cycle of the process automation system: vendors, engineering companies,
installers and operators. Increased flexibility and reduced risk are provided by the re-use of
the already installed fieldbus cabling, which provides a path for clear migration strategies.
This significantly reduces cabling cost as firewalls remain untouched.
Ethernet-APL supports all current and future higher-level communication protocols andservices and flattens the network infrastructure. Ethernet-APL removes the need for protocol
conversions and gateways, providing barrier-free and parallel accessibility and providing
the extra speed required in a data-driven economy. Table 2 compares major attributes ofcommunication technologies in use today.
Ethernet-APL combines the best attributes of Ethernet communication with two-wire installation
techniques. This makes Ethernet-APL easy to deploy as a standard for field app­lications,from process plants with hazardous areas up to Zone 0 / Division 1 to hybrid plants, employing
technologies from discrete and process automation. Since Ethernet-APL is the physical layer
only, any current and future concepts for functional safety and security applications can beapplied that reflects the needs of end users. New developments can be applied independentof the physical layer, providing long-term stability of the technology and protecting the investment in the installation.
Table 2: Technical comparison of communication technologies
Comparison ofTechnologies for the
Field of Process Plants

4-20 mA
with HART

Fieldbus

Ethernet
100BASE-TX

Ethernet
10BASE-T1L

Communication

1.2 kbit/s
half duplex

31.25 kbit/s half
duplex

100 Mbit/s
full duplex

10 Mbit/s
full duplex

Reference Cable

n/aType ‘A’

CAT 5 / 6

Type ‘A’

Trunk Lengthn/a1900 m (typ.
700 m)

100 m

1000 mSpur Length

n/a

120 m

n/a

200 m

Single Pair Cable

Screw Type Connector
Polarity independencen/aIntrinsic safety option
One network technology
from field to enterprise

1: Available up to 1 GHz, certified for Zone 1
2: Available by 100BASE-TX-IS from Intrinsically Safe Ethernet Working Group
3: Dependent upon vendor

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Device Development
and Implementation
Field devices oftentimes contain a lot of smart data about themselves, such as self-diagnostic
functionalities.
Ethernet-APL provides the optimal method to access this data in parallel to process control.
This technology provides access to the instrument separately, and thus combines thepotential of smart instrumentation with IIoT applications. This enables product managers
to design additional services, business models, and unique selling propositions for differentiation of the field device supplier. Ethernet-APL significantly reduces the costs to access thisbeneficial data in comparison to traditional technologies. Ethernet-APL reduces the need for
protocol converters, additional system components or retrofit solutions, which would otherwise be required.
The case for considering Ethernet-APL in field device implementation is strongly bolsteredby the expected market volume:
Ethernet-APL fulfills the requirements of process automation(e.g., hazardous areas, long cable reach, simple maintenance, etc.)
The availability of a single network technology opens new business potential
for both device manufacturers and plant managers based on access to datafrom smart instrumentation.
Large companies and SDOs focused on process automation are involvedin the APL Project and collaborate in the working groups, thus a high market
acceptance for the technology can be expected.
In order to strive for technological leadership in the market, Ethernet-APL
must be considered in the product portfolio in the near future.
Implementing Ethernet-APL in smart instruments requires limited effort only concerning
the PHY and the protocol stack. What must be considered during device implementation
specifically for Ethernet-APL? The answer is simple:
Ethernet-APL enhances the Ethernet physical layer. By implementing the corresponding
10BASE-T1L PHY in the field device hardware, the necessary connection is ensured.
Standard PHY chips are available from reputable chip manufacturers.
Due to the independence of the individual layers according to the ISO OSI model,
there are no restrictions for the implementation of any Ethernet protocol. Therefore,
no adaption is necessary for the implementation of Layer 3-7 protocols regarding
Ethernet-APL. Application layer protocols, which have been in use for many years,
especially in discrete automation, can easily be implemented according to their
existing specifications, guidelines, and certifications.
As part of the extension of the specifications on the Ethernet-APL physical layer, thecorresponding test specifications and certifications can also be adapted. This ensuresthat the implementations comply with the standards.

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Operation
Plant efficiency is becoming an increasingly important topic in process automation. For thispurpose, it must be ensured that a process plant operates reliably, provides information on
future maintenance intervals for the instrumentation, is easy to diagnose in case of failures,and works with devices from different device manufacturers. The basis for these aspects isthe continuous collection and analysis of data from the installed base.
Ethernet-APL supports all of the following requirements of a highly efficient process plant.
Reliability: Based on well-proven Ethernet standards, the reliable operation of theplant is ensured. Ethernet has been the standard in the IT world for decades and has also
been used successfully in discrete, process and hybrid automation for many years.
High availability: Ethernet protocol features ensure the high availability of the process byavailability concepts, e.g., system redundancy for controller failures or media redundancy
for cable breaks.
Predictive Maintenance: Smart field devices have the data for predictive maintenanceinside. With Ethernet technology, the data can be made accessible and used for central
monitoring of the device status.
Diagnostic: For Ethernet technology, easy network diagnostic tools are available toidentify the root cause and reasons for failures.
Interoperability: For Ethernet-APL, test specifications and certifications will be available
to ensure the interoperability of components from various device vendors and will also
support device exchanges.
Summarized, Ethernet-APL supports this new paradigm of data by the technology consistency
in and across the automation pyramid. With Ethernet technology in the field of process
plants, operational technology (OT) is integrated with IT technology, and the vision of thesingle network technology is achieved.
The access to the data of the field enables new digital services according to the businessneeds of the process plant. Ethernet technology provides access to this information in
real-time. There are hardly any limits to the further processing of the data within the framework of IIoT applications, for example those required by NAMUR Open Architecture (NOA).
Maintenance dashboards or trend monitoring of process values support the specific processoptimization.

13

Other Applications

Engineering

Asset Management

Controller
Optimization& monitoringData
analysis

Auxiliary PowerAPL Field Switch

Zone 2/Div. 2

Process value
visualization

Zone 1/Div. 2
Zone 0/Div. 1

Facility Ethernet
Ethernet-APL with
Intrinsic Safety Option

Figure 6: Networking the entire automation pyramidPrototyping & Engineering
Working habits and procedures based on Ethernet-enabled software and tools provide ahigh degree of automation to engineering within the field of process plants. Current andcoming generations of engineers master these technologies with ease. Ethernet-APL enables
the easy integration of these features into the field of the process plant. With this, engineers canmeet their project schedules through automation of many tasks.
Software tools simplify or automate:
Network planning
Creation and design of typical control loops
Access to all details stored in the instrument such as:
Device drivers and descriptions, e.g. FDI package
Manuals
Certification
Instrument parametrization and configuration
Instrument diagnostics during operation

14

Engineering and maintenance of protocol converters and gateways will become obsolete.
App-supported work procedures running on smart phones or computers satisfy the
expectations of the new work force. Developers and experts of the SDOs and suppliers
involved in The APL Project are in the process of developing guidelines and best practices
for planning and installation. This facilitates an easy transfer of knowledge for early adoptionof Ethernet-APL. Standard Ethernet diagnostic tools assist new or seasoned instrument
techs and engineers in their daily work, providing a shallow learning curve.
Once all standards and guidelines are available, a broad base of vendors are able to adopt
Ethernet-APL in their devices or other product offerings. Companies providing engineering
services to vendors and users already show an interest. It can be expected that a robust
eco-system will evolve.

Installation in the Field
The network skills required by a new generation of electricians and instrument technicians
are the result of numerous network upgrades, which many plants introduce to access andextract more data across their process automation systems. Wired or wireless, Ethernet has
become part of the fabric of everyday life at home, in the office, and on the plant floor. Fromrouters, switches and wireless access points, the only additional feature integrated in EthernetAPL is the two-wire physical layer, including intrinsically safe ignition protection providing
the same installation and protection rules that are familiar to field and instrument technicians.
The instruments are not allowed to disturb one another and are only configured in a peerto-peer manner. With features like polarity protection and the mandatory terminations insidethe devices, the technology provides for a smooth and short learning curve.
While today’s technician may require time to calibrate, configure, and prepare an analog fielddevice prior to installation, the time spent preparing a digital field device will be significantly
reduced. Supporting techniques include apps and wizards for automatic network setup,device discovery, configuration, and instantiation – as soon as the field device is installed andconnected. The 2-wire Ethernet-APL cable allows the use of higher speed data transfer tosimplify the installation and allow the technician to complete an assignment with confidence
in very little time.
Together with a screwdriver, the handheld data device (such as a smart phone), cable test
devices, and an improved user configuration will become additional parts of the technician
toolbox in the transition from the analog to the digital field instrument with the related infra­
structure devices.

15

Project Scope, Timeline
and Conclusion
The consideration of techniques providing power and data with high bandwidth on two wires
inspired developers to develop a common physical layer that serves the needs of process
plants. The experts created and published the vision for process plants: “Ethernet to the Field”.
This evaluation project for the Advanced Physical Layer for Ethernet started in 2011 by a groupof device suppliers. The objective of the evaluation project was to define a solution that
fit the harsh requirements of process automation that didn’t affect the application layer
protocols and therefore the established Industrial Ethernet protocols. In 2016, the evaluation
project ended successfully with identified enhancements of relevant specifications.
The project to develop Ethernet-APL has already achieved first milestones as visible in the
infographic. Together with the release of the 10BASE-T1L specification in IEEE, the progressof IEC specifications for 2-Wire Intrinsically Safe Ethernet (2-WISE) and power port profiles
is on track. Final PHY chips will be available in early 2021, so the first field devices andinfrastructure components are expected to be available in 2021 as well. For the installationof an Ethernet-APL system, an Engineering Guideline will be available in time.
A first pilot project with Ethernet-APL prototypes in Germany proved the working principle
and the benefits of the technology. The installation of 2-wire Ethernet field devices, bothactuators and sensors for all kinds of measuring types, prove the simplicity of field device
installation, integration in the process automation systems, and the parallel access to thedata of field devices.

The Ethernet Advanced Layer
2018: Start ofoﬃcial APL
project

2015: Proof ofﬁrst concept
shown

IEC TS 60079-47
2WISE forintrinsic safety

Series PHY-chips
for integration
into products

Test & demo
facilities open

Engineering
guideline

IEC technicalspeciﬁcation forport proﬁlesIEEE 802.3cg-2019
10BASE-T1L

Publication ofindustrial Ethernet
network
speciﬁcationsFirst ﬁeld devices
and infrastructure
available

Ethernet-APL
conformance test
speciﬁcations

Technology launch
2021

Completed
Work in progress
Planned16

Follow us on the journey to an
Ethernet to the ﬁeld of process plants

Meeting all these requirements will favor acceptance by users:
extends easily into existing plants,
enables transparency and open, parallel access to proven-in-use field instrumentation,
ensures interoperability based on a single network,
provides standardized and well-accepted procedures for explosion hazardous areas,
achieves simple, flexible and vendor-independent use of all device functionality.
Enhanced connectivity provides a powerful tool to reduce complexity in daily operation
and work. The availability of a single network technology opens new business potential forboth device manufacturers and plant managers based on access to data from smart
instrumentation.

With the Advanced Physical Layer
for Ethernet, the vision becomesreality for process plants:“Ethernet to the Field”

17FieldComm Groupwww.fieldcommgroup.org/apl

ODVA
www.odva.org/apl

OPC Foundationwww.opcfoundation.org/apl

Profibus and Profinet International (PI)www.profibus.com/apl

September 2020