QoS - Application of TSN to EtherNet/IP Networks
Jordon Woods
Director, Deterministic Ethernet Technology Group
Analog Devices, Inc.
Steve Zuponcic
Technology Manager
Rockwell Automation
Presented at the ODVA2017 Industry Conference & 18th Annual Meeting
February 21-23, 2017
Palm Harbor, Florida, USA
Abstract
Deterministic Ethernet is already widely used in industrial control systems. Many Industrial protocols solve
the problem of determinism over Ethernet using proprietary layer 2 solutions. The new IEEE 802.1 TSN
standards are aimed at the same class of problems encountered in industrial control and promise tosupplant proprietary solutions in favor of a standards-based approach. EtherNet/IP has always relied
upon standard, commercially available Ethernet technologies to deliver deterministic performance and istherefore well-positioned to leverage these emerging standards.
In this paper we discuss specific use cases and examine how the emerging TSN standards can beapplied to EtherNet/IP networks to provide improved determinism and performance. We will also contrast
the results expected in a TSN-based network with those of the technologies currently in use.
Keywords
Industrial Ethernet, Industrial Control, Motion Control, EtherNet/IP, CIP Motion, CIP Sync, Time-Sensitive
Networking, Audio-Video Bridging, AVB, AVB Gen2, software-defined networking, SDN, deterministic
Ethernet.
Definition of terms (optional)
Bridge: A system that includes Media Access Control (MAC) Bridge or Virtual Local Area Network (VLAN)
Bridge component functionality and that supports a claim of conformance to Clause 5 of IEEE Std
802.1Q-2014 for system behavior. Note: “Bridge” is often used interchangeably with “switch” in TSN
discussions.
Centralized Network Configuration (CNC): A centralized component that configures network resources onbehalf of TSN applications (users).
Centralized User Configuration (CUC): A centralized component that discovers and configures application(user) resources in end stations. The CUC exchanges information with the CNC to configure TSN
features on behalf of its end stations.

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Credit Based Shaper: A prioritization mechanism that operates on one or more outgoing queues in a
bridge and guarantees “fairness” on the wire by providing lower priority traffic access to the network whenhigher priority traffic have exhausted their “credits” during a given frame of time.
End station: A device attached to a local area network (LAN) or metropolitan area network (MAN), whichacts as a source of, and/or destination for, traffic carried on the LAN or MAN.
Grandmaster: The time-aware system that contains the best clock, as determined by the best masterclock algorithm (BMCA), in the generalized precision time protocol (gPTP) domain.
Listener: The end station that is the destination, receiver, or consumer of a stream.
Stream: A unidirectional flow of data from a Talker to one or more Listeners.
Synchronized time: The synchronized time of an event is the time of that event relative to the
grandmaster.
Synchronized time-aware systems: Two time-aware systems are synchronized to a specified uncertainty
if they have the same epoch and their measurements of the time of a single event at an arbitrary timediffer by no more than that uncertainty.
Talker: The end station that is the source or producer of a stream.
Traffic class: A classification used to expedite transmission of frames generated by critical or timesensitive services. Traffic classes are numbered from 0 to N-1, where N is the number of outboundqueues associated with a given Bridge Port, 1 <= N <= 8, and each traffic class has a one-to-one
correspondence with a specific outbound queue for that port. Traffic class 0 corresponds to nonexpedited traffic; nonzero traffic classes correspond to expedited classes of traffic. For a given priority
associated with a frame and a given number of traffic classes, a fixed mapping determines which trafficclass will be assigned to the frame.

Deterministic Ethernet Overview
Deterministic Ethernet refers to an extended set of capabilities that allow standard Ethernet to be used inreal-time, mission critical applications such as Factory Automation, Process Control, and Automobile
Networks.
Ethernet has traditionally been a "best-effort" network. To allow Ethernet to be deployed in mission criticalapplications, it is necessary to add specific features including time synchronization, scheduled traffic,
ingress policing, seamless redundancy and others. These features allow network designers to ensurethat certain classes of traffic can be delivered on time, every time throughout the entire network topology.
Deterministic Ethernet started in the factory automation market, where large OEMs defined their own
methods for adding these capabilities to Ethernet and this has spawned a number of "open standards"
that are used in Industrial Ethernet today. ODVA has deployed deterministic Ethernet networks, with timesynchronization and quality of service for critical traffic, for many years.
The IEEE standards organization is currently working to add Time Sensitive Networking (TSN) features tostandard 802.1 and 802.3 Ethernet to provide deterministic performance. When this work is completed, it
will become practical to deploy standard TCP/IP Ethernet (with the TSN extensions) in real-time, mission
critical applications. However, it is unlikely that the existing industrial protocols will be replaced by TSN.
It is more likely that they will be adapted to make use of the inherent deterministic capabilities provided by
TSN.
The goal behind the new TSN standards is to achieve a truly converged network where all classes oftraffic can seamlessly coexist. This would allow mission critical real-time traffic to coexist on the same2017 ODVA Industry Conference2©2017 ODVA, Inc.

network as traditional QoS prioritized traffic and best-effort traffic. A major driving force behind thedevelopment of these new TSN standards is the emerging Automotive Ethernet market. However,Industrial Automation market share many common requirements with automotive control applications andcan therefore leverage the standard technologies and economies of scale inherent in this very large
market.
It is important point to note that the new IEEE standards are based on some of the same basic
techniques that have been used in the Industrial Ethernet protocols for many years. However, manyorganizations have relied upon proprietary layer 2 techniques to achieve determinism. In contrast, ODVA
and EtherNet/IP have relied exclusively on widely available, ubiquitous standards from IEEE and otherorganizations. For this reason, ODVA is uniquely poised to successfully leverage the emerging TSN
standards.
TSN and the Distributed Motion and Time Synchronization SIG
ODVA has tasked the Distributed Motion and Time Synchronization SIG with evaluating how to merge
these TSN standards into the existing CIP standards. It is a common misconception that TSN is a single
standard. In reality, TSN is a set of new standards and enhancements to exiting standards. In otherwords, TSN is a basket of new Ethernet features including:•Time Synchronization
In the context of TSN, Time synchronization refers to proposed modifications to the existing IEEE
P802.1AS standard that was defined for Audio Video Bridging. To understand the proposedchanges, first we should describe IEEE 802.1AS.
IEEE802.1AS is the Audio-Video Bridging (AVB) profile of the IEEE1588 Precision Time Protocol.
IEEE1588, and therefore IEEE802.1AS uses a master-slave protocol to synchronize real-timeclocks in the nodes of a distributed system that communicates using a network. In simple terms,
PTP ensures that every node on the network knows what time it is. It does not specify what agiven node does with its knowledge of time. The AVB profile (IEEE802.1AS), has features
tailored to the “plug and play requirements” of AVB components. It does not use “transparent
clocks” to compensate for bridge latency because transparent clocks violate IEEE802 layering
conventions. Instead, each node accepts time information from the best available master clock
and produces a slave clock, in a manner similar to a boundary clock, to compensate for latency.
By nature, this approach is peer-based. This approach is not compatible with end-to-end
transparent clock defined as default IEEE-1588 profile and used in CIP Sync. For this reason,time-bridging mechanisms need to be developed to allow existing technologies and installations
to migrate into the newer TSN domains. By developing time gateways, brownfield installations
can be included in the larger TSN eco-system and benefit from many of the new features andcapabilities that TSN has to offer.
The End-to-End TC function does not require all nodes to be time aware which is important inbrownfield installations. While time accuracy will be compromised if there are non-time-aware
nodes, a common understanding of time is maintained among the time-aware nodes. In contrast,
the Peer-to-Peer mechanism utilized by IEEE802.1AS requires every node be time-aware.
Obviously, this requirement is not practical for brownfield uses cases.

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Figure 1 - Peer-to-Peer and End-to-End Clock systems

IEEE802.1AS-REV introduces new features needed for time-sensitive applications. Thesefeatures include the ability to support a multiple time domains to allow rapid switchover, should aGrandmaster fail, and a more precise measurement of time.
While time synchronization is a foundational component of most TSN features (AVB, ingresspolicing, scheduled traffic), none of these features require that specific PTP profile be utilized. For
instance, ingress policing requires an understanding of time that can come from the default
IEEE1588v2 profile, the IEEE802.1AS profile, or some other PTP profile.
•

Scheduled Traffic
Applications implementing control loops over Ethernet (factory automation, robotics, automotive
control systems) require delivery of control data at precise times with minimal latency and jitter.
Existing priority mechanisms provide for prioritization of traffic or guarantees of bandwidth (AVB),
but the time of delivery is unpredictable. IEEE802.1Qbv supports this requirement by divided
Ethernet traffic into different classes thus ensuring that, at specific times, only one traffic class (orset of traffic classes) has access to the network. This division, in effect, creates a protected“channel” that is used by that traffic class alone. For clarity, this traffic class is scheduled traffic in
all cases, and scheduled traffic is given the highest priority on the wire.
As shown below IEEE802.1Qbv accomplishes this division by introducing time-aware“transmission gates”. These gates are used to enable separate transmission queues. The Qbv
shaper provides a time-based circular schedule which opens and closes the transmission gate at
specific times. Note that once a gate is open, existing IEEE802.1Q transmission selection
algorithms function normally. A given queue may operate on strict priority (best effort) basis while
another may use the credit-based shaper defined for AVB applications. However, it is worth
noting that IEEE provides no guidelines regarding which QoS/traffic-shaping mechanism to use ina given situation. Such uses cases are application-specific. It will fall to industry bodies such as
Avnu and ODVA to develop TSN profiles for these use cases. This task is vitally important inproviding system models and behaviors that are consistent across applications and even within
the same application. Without consistent models and behaviors, one CNC may configure a
network in one way – while another CNC may configure the same network in a different way.

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Figure 2 - IEEE802.1Qbv Queuing Structure•

Preemption
Today’s infrastructure components are designed to complete transmission of an entire packet
before the next packet can be transmitted, if the initial packet has already been placed in theegress port. Therefore, a 1500 byte packet of lower priority can “hold off” a higher priority packet(~120 us at 100Mb/s wire speed). Preemption (also called Interspersing Express Traffic per
IEEE802.3br/IEEE 802.1Qbu) defines a mechanism that allows the switch to stop a transmission
in mid-stream in order to allow a higher priority packet to move through the system. Note that only
one level of traffic is defined as preemptive.

Figure 3 - Preemption•

Seamless Redundancy
Frame Replication and Elimination for Reliability (IEEE P802.1CB)To ensure robust and reliable communication, control systems must be tolerant to packet loss
due to congestion, link failures, cable breakage and other faults. To minimize the impact of such
faults, P802.1CB aims to send duplicate copies of critical traffic across disjoint paths in the
network. If both frames reach their destination, the duplicate copy is discarded. If one copy fails to2017 ODVA Industry Conference

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reach its destination, the duplicate message is still received, effectively providing seamless
redundancy.
To minimize network congestion, packet replication can be selected based upon address/trafficclass and path information. Likewise, duplicate frame elimination can be based upon
address/traffic class and timing. In other words, only critical traffic need be replicated. Best effort
and other traffic tolerant to congestion loss can still be transmitted normally.
•

Ingress Policing
Ingress policing generically refers to methods used to prevent traffic overload conditions (e.g.,Distributed Denial of Service or DDoS or erroneous delivery) from affecting the receiving node or
port. These methods may be used to protect against software bugs on endpoints orswitches/bridges but also against hostile devices or attacks. P802.1Qci proposes to provide
filtering on a per stream (traffic class) basis by providing an input gate for each stream. These
gates would be responsible for passing or blocking a given stream or streams based upon apolicing function. Supported functions include a time window (only allowing streams to pass at a
certain time), only allowing specific streams to pass on specific ingress ports, a maximum burst
size, a leaky bucket algorithm and others. Note: a leaky bucket algorithm checks that streams
conform to defined limits on bandwidth and burstiness (a measure of the unevenness orvariations in the traffic flow). Thought of another way: each talker has a contract with a respective
listener (excess bandwidth, burst sizes, packet sizes, misuse of labels, etc.). The input gate
serves to enforce that contract.

•

Centralized Configuration
IEEE P802.1Qcc (Stream Reservation Protocol (SRP) Enhancements & Performance
Improvements) enhances the existing Stream Reservation Protocol with the addition of a User
Network Interface (UNI) which allows for a centralized network configuration (CNC) entity. This
CNC can then provide a centralized means for performing network calculus, scheduling and otherconfiguration via a remote management protocol such as NETCONF or RESTCONF. A
Centralized User Configuration (CUC) entity communicates to the CNC via a standard API. The
CUC may be used to discover end stations, retrieve end station capabilities and user
requirements, and configure TSN features in end stations.

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Industrial Control Overview
Modern industrial networks combine the disciplines of both information technology (IT) and operational
technology (OT) to meet the requirements of industrial applications The applications served by theindustrial control sector are sophisticated processes requiring complex and modularized designs that
often require modification and augmentation during runtime. These applications require highperformance, determinism, and predictability; their infrastructures demand highly robust and reliable
designs both in hardware durability and in resiliency features to support high-availability needs.
The networking legacy in the industrial control market is long established with roots that extend to multiple
industrial technology standards as well as to multiple vendor-specific, proprietary technologies. The
industrial installed base that has settled on these technologies is a conservative community of
manufacturers that move carefully and slowly from one generation of technology to the next. Solutions
need to be proven and ROI is carefully calculated before investments are made. The move from any
current position is always done through migration and evolution in order to protect installed assets and to
maximize profitability for any given change in architecture.
Prior to the advent of TSN technologies, there hasn’t been much motivation to drive these differing
industrial solutions to a more unified approach. The TSN conversation, however, has driven anawareness that future networking solutions will require a holistic approach and a true system perspective.
The future network requires a comprehensive answer that includes all elements - infrastructure and end
stations alike – to be included in the final solution. Moreover, in order to solve the complete Industrial
Internet of Things (IIoT) problem statement, this comprehensive solution will require the collaboration of
the existing, differing, technologies and standards to morph toward solutions that can allow their inclusionin this new eco-system. If any specific technology, vendor, or product does not participate in this newparadigm, there is no way for “the system” to accommodate or plan for the traffic that needs to be
managed to or from these components. The result is that these components will either not be properly
served in the overall design – or that they will interfere with the overall design in a non-productive fashion.

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Industrial Use Case
Consider the following representative architecture of an industrial control application and associatednetwork design:

Figure 5 – Industrial Use CaseIn this system, an industrial process is controlled by a single machine which consists of four different
sections of machinery. Each section of machinery is delivered to the process via different OEMs, each ofwhich have different specialties in the parts of the process that they control. The end user has 7
manufacturing sites around the globe. There are 15 of these machines per site, and each machine IP
addressing scheme is identical to the other machines in the same manufacturing facility, which matches
the other addressing schemes of the other facilities. Moreover, each machine section is a subnet with aunique VLAN so that the equipment can be constructed modularly and functional organization isachieved. All sections of the machine are synchronized and coordinated to produce final product andrelevant events are timestamped so that data on the manufacturing floor can be correlated against data in
the MES system and data from the supply chain. The entire manufacturing facility uses the sameunderstanding of absolute time and all events are related back to the common notion of “wall clock time.”
Additionally, this use case acknowledges the pre-existence of products and technologies that utilize other1588 based solutions. In this case, component A in Machine Section A may communicate withcomponent A’ in Machine Section C; Component B in Section A may communicate with component B’ in
Machine Section D. Finally, component C in Machine Section A produces data to be consumed by C’components in sections B, C, and D. The implementation of time bridges or time gateway mechanisms
via the switches provides a migration path for an extended community of existing products andtechnologies to be included in the wider TSN value proposition. In this use case, components A and A’,
and B and B’ would require time gateway translations.
Scope and timing
It’s important to note that the use case given above is typical for a very wide range of industrial
applications. This use case illustrates the need for solutions at layer 2 (switching), layer 3 (routing) and fortime bridging functions.

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Today, the IEEE-802.1 TSN Workgroup focuses on layer 2 in the architecture and this is where themajority of TSN work is being defined. Here, there is work complete enough to begin implementation in asystem or in a product. Additionally, AVnu has defined compliance specifications sufficient enough tocertify some products for this level of operation. This version of the “Theory of Operation” document
focuses on the technology in this part of the architecture and will expand its scope in future versions toinclude other areas as those technologies become defined.
Layer 3 (routing) functionality is currently being designed by the Internet Engineering Task Force (IETF)
and it essentially extends the capabilities of the 802.1 TSN specifications into layer 3. This work, often
called “Detnet”, (deterministic network) is not yet complete, at the time of this writing.
Time bridging, also referred to as time gateway capability, is shown in the layer 2 switches and provides
the mechanism for migrating legacy technologies into a TSN system. This functionality has not been
identified as a required work item for any standards communities. Individual suppliers could developthese bridge functions as solutions for the market.
Finally, it shouldn’t go unnoticed that a CNC device is shown in this diagram as the centralized
configuration tool that is used to manage the network and ensure proper management of networking
traffic and streams for this given application. This is consistent with the concepts discussed abovearound Figure 4 where CNC and CUC relationships are described.
Effect of TSN features on Control Applications
To examine the effects TSN can have on control applications, let us consider the model depicted below:

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This model consists of a controller and drives connected through an infrastructure consisting of “m” switch
hops. Input data must arrive at Controller before the end of the input interval. Planned data outputs
should be transmitted before the end of the planner interval. Output data must arrive at the drive before
the end of the output interval. For the sake of simplicity, these intervals are divided in thirds at an update
rate of 1 mS. Further the model assumes:••••

All network elements are time-aware
Standard QoS/priority throughout.
Cut-through switching (cut-through latency ~2usec @ 100 Mbs; ~1usec @ 1 Gbs)
Some control of traffic volume and the size of interfering traffic on the network

This analysis will focus on a part of the problem associated with network performance. Variables such as
controller/drive latency are assumed to be understood and constant. A simple, mathematical model
describing such a system is given by:
Max Axis = 1 + {1/3 * Connection Update Period – (Drive Transmission Delay + (m + 1) *Ethernet Transmission Time + m * Switch Latency + NIC Packet Processing Delay + Bus
Interface Delay)}/NIC Packet Processing Delay







(Where m = # of hops)
Drive Transmission Delay: We’ll assume all drives have outputs queued prior totransmission, so this is contribution is small with respect to other operands, effectively 0
usec
Assume update packets are fairly small(124 bytes), so Ethernet Transmission Time is(124+20)*80ns/byte = 11.52 usec (at 100 Mbs)
Switch Latency = (interfering packet size+20)*80ns/byte
NIC Packet Processing Delay – There are techniques to ensure the network is thebottleneck (e.g. 2 cycle processing): 11.5 usec for 100 Mbs, 1.15 for Gigabit.
Bus Interface Delay: has a lot to do with the overall system architecture. Delay could go
effectively to 0 (given good bus structure, DMA/ etc.). We’ll assume 0 for this analysis.

Ideally, we’d like all of the drives to transmit their output data simultaneously. In this way, the link between
the controller and bridge is optimally utilized. As shown below, performance is strongly influenced byinterfering traffic and thus, the number of hops. In practice, control systems will engineer the network tolimit the size of interfering packets (the example below assumes 100 Mbs link speed with both 1500 and
500 bytes of interfering traffic).

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Figure 7 - 100 Mbs Baseline
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Preemption offers a standard, unified means to limit the effects of interfering traffic. With a maximum
fragment size of 64, the maximum interfering frame size is:(2*64 bytes)-1 =127 bytes
Thus, Preemption simplifies the problem of isolating the control network from interfering traffic. The
network designer still needs to ensure that other traffic of the same priority is not present on the wire orthat bandwidth is sufficient to deal with all such traffic.

Figure 8 - 100 Mbs w/ Preemption

Utilization of a line topology and scheduled traffic can further minimize effect of interfering traffic. As
shown below, the schedule of drives can be individually adjusted to compensate for drive transmission
delay, transmission time and switch latency.

Figure 9 - Use of Line Topology to Minimize the Effects of Switch Latency

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Thus, the effects due to switch latency are minimized and the effects of interfering traffic are of lessconsideration than the ability of the controller to process incoming packets. This example still assumes asomewhat isolated network (i.e. there is no other traffic of the same class which might interfere with
control packets).
As shown below, Gigabit transmission speeds further reduce the effects of interfering traffic. Note that thebenefit from scheduled traffic across hops is much less significant.

Figure 10 - The effects of Gigabit Link Speeds2017 ODVA Industry Conference

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Models vs. Reality
It is worth noting that what is shown in this analysis is a simple model intended to illustrate the effects of
TSN on an Ethernet-based control solution. There are many potential points of optimization in a complex,
real-world system. Assumptions made herein are for the purpose of discussion, not to suggest design
approaches or solutions.
You will never strike oil by drilling through the map! BUT: this does not, in any way, diminish the valueof a map! (Solomon Golomb: Mathematical models – Uses and limitations. Aeronautical Journal
1968)• Source: Dr Edward Lee (UC Berkley) TSNA’15 – The Internet of Important Things
For instance, the model used herein assumes a very conservative 11.5 microseconds for “NIC Packet
Processing Delay”. If one assumes that the system bottleneck is the network, rather than controller
packet processing, then Gigabit speeds show drastically improved results.

Figure 11 - Improved Gigabit Performance

The Distributed Motion and Time Synchronization SIG uses a more sophisticated model for modelingmotion problems. This tool is proprietary to ODVA and is therefore not included as part of this paper, but
results from that model validates the results contained herein.

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Figure 12 - Impact of Wire Speed vs. TSN Functionality per the CIP Motion Model(Distributed Linear Segment Topology)

Wire speed contributes to the majority of throughput and performance on the wire. TSN functions allow
for better “packing” of data at any given wire speed. Preemption offers a standard, unified means to limit
the effects of interfering traffic control systems. Analysis suggests many control applications could beserved with Gigabit Ethernet and preemption without the additional complexity of scheduled traffic.

Network Convergence and Centralized Configuration
Given these results, one can reasonably ask whether industrial applications need to consider scheduled
traffic. Certainly, the data would suggest that the benefits of scheduled traffic for control applications are
not as dramatic as one might expect, particularly at Gigabit speeds. However, it is important to remember
that, as deployment of Ethernet in Industrial Automation grows data access from Industrial networks
become more desirable. As the Enterprise and Automation networks become more integrated, data flows
from various applications must converge.
The centralized configuration model proposed in IEEE802.1Qcc provides a practical approach forachieving this vision of convergence. Such convergence requires publication of network traffic
requirements to and from disparate and possibly conflicting traffic sources. Scheduled traffic is one of thetools that the CNC can use manage and resolve these conflicts.
Referring to the use case outlined in “Error! Reference source not found.igure 5 – Industrial Use Case”,
we see that a centralized network control entity can be used to configure individual subsystems and that a
CNC entity can be used to integrate these various pre-configured subsystems. In this sense, TSN isclosely aligned with Software Defined Networking (SDN) concepts. Software Defined Networking or SDN
is an approach to computer networking that allows network administrators to manage network services
through abstraction of lower-level functionality. This translates to providing a system level view of network
configuration and management vs. the traditional component level view.

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Figure 13 - Concept of tomorrow’s configuration view

This approach also lends itself to network modeling prior to network commission. Given a known topology
and set of traffic requirements/constraints, the CNC can accurately predict network performance.

Conclusions
TSN technologies offer a scalable, predictable approach to deterministic networking. Because Ethernet/IP
products have always relied upon standardized technologies, ODVA is in an excellent position to leveragethese emerging standards. However, significant challenges remain. The integration of various PTP
profile and the convergence of EtherNet/IP traffic with a scheduled TSN network are chief among thesechallenges.

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References (optional)
1. Browne, B. Hotchkiss, M. Weingartner, T. "Real-Time Performance of Industrial Ethernet in Field
Devices.” November 7, 2011, http://www.innovasic.com/technology/PriorityChannel.
2. Alsup, D. Weingartner, T. "What is PriorityChannel™?” May 14, 2012,
http://www.innovasic.com/technology/PriorityChannel.
3. Chaffee, Mark. "CIP Motion Implementation Considerations." Proc. of ODVA 2009 Conference &13th Annual Meeting, Howey-in-the-Hills, Florida USA.
4. Frithjoh Klasen, Jürgen Jaskolla, “Profinet at VW de Mexico”, Profinet International – North
America General Assembly Meeting Presentation, Scottsdale, AZ, October 2011
5. Lee, Edward A. "Absolutely Positively on Time: What Would It Take?" Computer 38.1 (2005): 8587.
6. Lee, Edward A. "The Internet of Important Things?" TSNA 2015, Santa Clara, CA USA.
7. Prettyjohns, Keith, and Alsup, David. "Enhancing Determinism, Fault-Tolerance and Reliability inEtherNet/IP Systems." Proc. of ODVA 2009 Conference & 13th Annual Meeting, Howey-in-theHills, Florida USA.
8. Woods, Jordon. "Minimizing Contributions to System Delay from NIC Packet Processing in CIP
Motion and Other Real-Time Control Applications." Proc. of ODVA 2011 Conference & 14th
Annual Meeting, Phoenix, Az USA.
******************************************************************************************************************************************************The ideas, opinions, and recommendations expressed herein are intended to describe concepts of the author(s) for the possible useof ODVA technologies and do not reflect the ideas, opinions, and recommendation of ODVA per se. Because ODVA technologies
may be applied in many diverse situations and in conjunction with products and systems from multiple vendors, the reader andthose responsible for specifying ODVA networks must determine for themselves the suitability and the suitability of ideas, opinions,and recommendations expressed herein for intended use. Copyright ©2017 ODVA, Inc. All rights reserved. For permission to
reproduce excerpts of this material, with appropriate attribution to the author(s), please contact ODVA on: TEL +1 734-975-8840
FAX +1 734-922-0027 EMAIL odva@odva.org WEB www.odva.org. CIP, Common Industrial Protocol, CIP Energy, CIP Motion, CIP
Safety, CIP Sync, CIP Security, CompoNet, ControlNet, DeviceNet, and EtherNet/IP are trademarks of ODVA, Inc. All othertrademarks are property of their respective owners.

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