wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

37
Industrial Ethernet
Gaëlle Marsal
EDF Research and
Development
Denis Trognon
EDF Research and
Development
37.1 Introduction..................................................................................... 37-1
37.2 Industrial Ethernet.......................................................................... 37-2
What Does Ethernet Mean?. •. What Does Industrial
Mean?. •. Classification of Industrial Ethernet Solutions
37.3 Standardized Solutions of IEC 61158 and IEC 61784................ 37-5
EtherNet/IP. •. Foundation Fieldbus High-Speed Ethernet. •. .
SERCOS III. •. “Exotic Solutions”: EPA, Tcnet, Vnet/ IP,
PNET on IP
37.4 Features of Major Industrial Ethernet Solutions........................ 37-9
37.5 Synthesis........................................................................................... 37-9
Abbreviations............................................................................................... 37-9
References.................................................................................................. 37-10
37.1 Introduction
The distribution of automation functions in instrumentation and control (I&C) architectures arose in
the late 1970s with proprietary network solutions designed to fit an application’s performance. To ensure
interoperability between different products from different vendors, the IEC 61158 standard has been
created. However, due to manufacturers’ pressure, this lead only to a collection of several different specifications
corresponding to each vendor’s commercial offer.
Meanwhile, Ethernet (IEEE 802.3 [12]) became the standard solution in desktop communication
systems that implements the first two layers of the OSI Model (see Chapter 1) while TCP/IP protocols
(RFC 791 [15] and 793 [16], cf. Chapter 61 of this book) did so for layers 3 and 4.
Until the late 1990s, Ethernet could not be used at the plant floor because of its nondeterministic
medium access control method, called CSMA/CD (cf. Chapter 2). Even though the apparition of fullduplex
links and switching technology turned Ethernet into a candidate for plant floor communication,
it still could not guarantee a deterministic response time, mainly because frames could still be
delayed or lost inside switches. Such a behavior would not meet the requirements of real-time control
systems. Hence, to overcome this problem, vendors developed several different “Industrial Ethernet”
solutions.
Figure 37.1 illustrates the usual network segmentation in an industrial information system. The two
highest levels—corporate LAN and Industrial LAN level 3—do not support time-constrained application.
Standard Ethernet is generally deployed at those levels. On the contrary, Industrial Ethernet
solutions are designed to address the Industrial LAN requirements of the automation network and fieldbuses.
Indeed, real-time and critical applications are performed at those automation levels.
This chapter proposes not to focus on one specific solution but to give an overview of several available
commercial solutions.
37-1
© 2011 by Taylor and Francis Group, LLC