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

Industrial Ethernet 37-5
Advantage: Provides deterministic guaranties and hard real-time performances
Drawback: Uses specific network devices and specific stations; cannot coexist with other Industrial
Ethernet and standard Ethernet stations
Examples: EtherCAT, SERCOS III
37.3 Standardized Solutions of IEC 61158 and IEC 61784
Industrial Ethernet profiles have been included in the IEC 61158 standard (Industrial communication
networks—Fieldbus specifications) and IEC 61784 (Industrial communication networks—Profiles).
Indeed, except EtherCAT and Ethernet Powerlink, Industrial Ethernet profiles are added to existing
profile families (or CPF for Communication Profile Families). In this standard, a profile (or CP for
Communication Profile) is defined as a set of all-layer specifications while a family is a set of profile with
similar application layers.
Under the promise of better interoperability, 16 different Industrial Ethernet profiles are standardized
grouped in 11 families in IEC 61158 [1–6] and IEC 61784 [7–9], which are not more interoperable
than their ancestors, fieldbuses.
The Table 37.1, extracted from IEC 61158-1 [1], synthesizes all the industrial communication profiles
standardized in IEC 61158 and 61784. The Industrial Ethernet solutions are outlined in red.
Among these Industrial Ethernet, ProfiNet* is detailed in Chapter 40, EtherCAT in Chapter 38,
Ethernet Powerlink in Chapter 39, and Modbus in Chapter 36.
Before synthesizing the main features of standardized solutions, the ones not detailed in other chapters
of this section are briefly described.
37.3.1 EtherNet/IP
EtherNet/IP [18] is a communication standard supported by Open DeviceNet Vendor Association
(ODVA) and ControlNet International Association. As DeviceNet and ControlNet, EtherNet/IP uses a
messaging Common Industrial Protocol (CIP). This protocol is supported by Rockwell and Schneider
Electric. While ControlNet sets (in IEC 61158 part 6) to support its own messaging and DeviceNet uses
CAN as a carrier, EtherNet/IP stack uses Ethernet/TCP/IP as a means of transporting CIP messaging.
CIP is the higher layer protocol and is based on object-oriented approach. It defines objects for the messaging
application and objects to describe the devices.
The use of CIP messaging provides, in addition to the CIP team model, a set of features including
• CIPsync, which allows synchronizing clocks of network equipments to the milliseconds
and is based on the standard IEC 61588 protocol that defines the Precision Time Protocol
(PTP) [10]
• CIPSafety, which is an upper layer for functional security for CIP applications, standardized in
the IEC 61784–3 [9]
Ethernet/IP provides
• Services for cyclic exchanges of variables, called implicit transfers, based on multi-cast traffic in
UDP/IP
• Services to exchange event-based messages, called explicit transfers, based on TCP/IP traffic
The event-based messages over TCP/IP are used both for transmission of system information (configuration
and diagnostic operation) and for information in applications that do not require fast response
times.
* The classes listed in the standard (CC-A, CC-B, and CC-C) do not correspond to the real-time profiles ProfiNet RT,
or IRT, but are conformance classes reporting to the scope of functions needed.
© 2011 by Taylor and Francis Group, LLC