IEC 61784-2-21:2023

Industrial networks - Profiles - Part 2-21: Additional real-time fieldbus profiles based on ISO/IEC/IEEE 8802-3 - CPF 21

IEC 61784-2-21:2023 defines Communication Profile Family 21 (CPF 21). CPF 21 specifies a Real-Time Ethernet (RTE) communication profile (CP) and related network components based on the IEC 61158 series (Type 26), ISO/IEC/IEEE 8802‑3 and other standards.
For each RTE communication profile, this document also specifies the relevant RTE performance indicators and the dependencies between these RTE performance indicators.
NOTE 1 All CPs are based on standards or draft standards or International Standards published by the IEC or on standards or International Standards established by other standards bodies or open standards processes.
NOTE 2 The RTE communication profile uses ISO/IEC/IEEE 8802‑3 communication networks and its related network components and in some cases amend those standards to obtain RTE features.

Réseaux industriels - Profils - Partie 2-21: Profils de bus de terrain supplémentaires pour les réseaux en temps réel fondés sur l’ISO/IEC/IEEE 8802-3 - CPF 21

L'IEC 61784-2-21:2023 définit la famille de profils de communication 21 (CPF 21). La CPF 21 spécifie un profil de communication (CP) Ethernet en temps réel (RTE) et les composants de réseau connexes basés sur la série IEC 61158 (Type 26), l’ISO/IEC/IEEE 8802‑3 et d’autres normes.
Pour chaque profil de communication RTE, le présent document spécifie également les indicateurs de performance RTE correspondants et les dépendances entre ces indicateurs de performance RTE.
NOTE 1 Tous les CP sont fondés sur des normes ou projets de normes, ou des Normes internationales, publiés par l’IEC, ou bien sur des normes ou des Normes internationales établies par d’autres organismes de normalisation ou des processus de normalisation ouverts.
NOTE 2 Le profil de communication RTE utilise les réseaux de communication ISO/IEC/IEEE 8802‑3 et leurs composants de réseau connexes et amende dans certains cas ces normes, pour obtenir les fonctions RTE.

General Information

• Status: Published
• Publication Date: 04-May-2023
• ICS: 35.100.20 - Data link layer
• ICS: 35.240.50 - IT applications in industry
• Technical Committee: SC 65C - Industrial networks
• Drafting Committee: WG 9 - TC 65/SC 65C/WG 9
• Current Stage: PPUB - Publication issued
• Start Date: 31-Mar-2023
• Completion Date: 05-May-2023

Relations

• Replaces: IEC 61784-2:2019 - Industrial communication networks - Profiles - Part 2: Additional fieldbus profiles for real-time networks based on ISO/IEC/IEEE 8802-3
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61784-2-21
®

Edition 1.0 2023-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Industrial networks – Profiles –
Part 2-21: Additional real-time fieldbus profiles based on ISO/IEC/IEEE 8802-3 –
CPF 21

Réseaux industriels – Profils –
Partie 2-21: Profils de bus de terrain supplémentaires pour les réseaux en temps
réel fondés sur l’ISO/IEC/IEEE 8802-3 – CPF 21

IEC 61784-2-21:2023-05(en-fr)

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IEC 61784-2-21

®


Edition 1.0 2023-05




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE











Industrial networks – Profiles –

Part 2-21: Additional real-time fieldbus profiles based on ISO/IEC/IEEE 8802-3 –

CPF 21



Réseaux industriels – Profils –

Partie 2-21: Profils de bus de terrain supplémentaires pour les réseaux en


temps réel fondés sur l’ISO/IEC/IEEE 8802-3 – CPF 21













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 35.100.20; 35.240.50 ISBN 978-2-8322-6914-5




Warning! Make sure that you obtained this publication from an authorized distributor.

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® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – IEC 61784-2-21:2023 © IEC 2023
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions, abbreviated terms, acronyms, and conventions . 7
3.1 Terms and definitions . 7
3.2 Abbreviated terms and acronyms . 8
3.3 Symbols . 8
3.4 Conventions . 9
4 CPF 21 (FL-net) – RTE communication profiles . 10
4.1 General overview . 10
4.2 CP 21/1 . 10
4.2.1 Physical layer . 10
4.2.2 Data-link layer . 10
4.2.3 Application layer . 13
4.2.4 Performance indicator selection . 17
Bibliography . 25

Figure 1 – Protocol stack for Type 26 fieldbus . 11

Table 1 – CPF 21 symbols . 9
Table 2 – CPF 21: Overview of profile sets . 10
Table 3 – DL-layer protocol / service suite selection . 12
Table 4 – Data transmission service selection . 12
Table 5 – Port number selection . 13
Table 6 – IP address selection . 13
Table 7 – CP 21/1: AL service selection . 14
Table 8 – Service selection of Subclause 6.5.4 and 6.5.6 . 15
Table 9 – CP 21/1: AL protocol selection . 16
Table 10 – Protocol selection of Subclause 5.2 . 17
Table 11 – CP 21/1: Performance indicator overview . 18
Table 12 – CP 21/1: Performance indicator dependency matrix . 18
Table 13 – CP 21/1: Consistent set of PIs for CM1 and CM2 (Erate = 100 Mbit/s) . 24
Table 14 – CP 21/1: Consistent set of PIs for CM1, CM2 and CM3 (Erate = 100 Mbit/s) . 24
Table 15 – CP 21/1: Consistent set of PIs for CM1, CM2 and CM3
(Erate = 1 000 Mbit/s) . 24

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IEC 61784-2-21:2023 © IEC 2023 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

INDUSTRIAL NETWORKS –
PROFILES –

Part 2-21: Additional real-time fieldbus profiles
based on ISO/IEC/IEEE 8802-3 –
CPF 21

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
Attention is drawn to the fact that the use of some of the associated protocol types is restricted
by their intellectual-property-right holders. In all cases, the commitment to limited release of
intellectual-property-rights made by the holders of those rights permits a layer protocol type to
be used with other layer protocols of the same type, or in other type combinations explicitly
authorized by their respective intellectual property right holders.
NOTE Combinations of protocol types are specified in the IEC 61784-1 series and the IEC 61784-2 series.
IEC 61784-2-21 has been prepared by subcommittee 65C: Industrial networks, of IEC technical
committee 65: Industrial-process measurement, control and automation. It is an International
Standard.
This first edition, together with the other parts of the same series, cancels and replaces the
fourth edition of IEC 61784-2 published in 2019. This first edition constitutes a technical revision.

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– 4 – IEC 61784-2-21:2023 © IEC 2023
This edition includes the following significant technical changes with respect to
IEC 61784-2:2019:
a) split of the original IEC 61784-2 into several subparts, one subpart for the material of a
generic nature, and one subpart for each Communication Profile Family specified in the
original document;
b) expand Common-memory-area as a new Common-memory-area-3 (CM3);
c) add new services and the protocols with expansion of Common-memory-area:
– Extended-cyclic-data service and the protocol;
– Extended-participation-req service and the protocol;
– Extended-network-parameter-read service and the protocol;
– Extended-network-parameter-write service and the protocol;
d) add new Table for CP 21/1: Consistent set of PIs with CM3.
The text of this International Standard is based on the following documents:
Draft Report on voting
65C/1209/FDIS 65C/1237/RVD

Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts of the IEC 61784-2 series, published under the general title
Industrial networks – Profiles – Part 2: Additional real-time fieldbus profiles based on
ISO/IEC/IEEE 8802-3, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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IEC 61784-2-21:2023 © IEC 2023 – 5 –
INTRODUCTION
The IEC 61784-2 series provides additional Communication Profiles (CP) to the existing
Communication Profile Families (CPF) of the IEC 61784-1 series and additional CPFs with one
or more CPs. These profiles meet the industrial automation market objective of identifying Real-
Time Ethernet (RTE) communication networks coexisting with ISO/IEC/IEEE 8802-3 –
commonly known as Ethernet. These RTE communication networks use provisions of
ISO/IEC/IEEE 8802-3 for the lower communication stack layers and additionally provide more
predictable and reliable real-time data transfer and means for support of precise
synchronization of automation equipment.
More specifically, these profiles help to correctly state the compliance of RTE communication
networks with ISO/IEC/IEEE 8802-3, and to avoid the spreading of divergent implementations.
Adoption of Ethernet technology for industrial communication between controllers and even for
communication with field devices promotes the use of Internet technologies in the field area.
This availability would be unacceptable if it causes the loss of features required in the field area
for industrial communication automation networks, such as:
• real-time,
• synchronized actions between field devices like drives,
• efficient, frequent exchange of very small data records.
These new RTE profiles can take advantage of the improvements of Ethernet networks in terms
of transmission bandwidth and network span.
Another implicit but essential requirement is that the typical Ethernet communication
capabilities, as used in the office world, are fully retained, so that the software involved remains
applicable.
The market is in need of several network solutions, each with different performance
characteristics and functional capabilities, matching the diverse application requirements. RTE
performance indicators, whose values will be provided with RTE devices based on
communication profiles specified in the IEC 61784-2 series, enable the user to match network
devices with application-dependent performance requirements of an RTE network.

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– 6 – IEC 61784-2-21:2023 © IEC 2023
INDUSTRIAL NETWORKS –
PROFILES –

Part 2-21: Additional real-time fieldbus profiles
based on ISO/IEC/IEEE 8802-3 –
CPF 21



1 Scope
This part of IEC 61784-2 defines Communication Profile Family 21 (CPF 21). CPF 21 specifies
a Real-Time Ethernet (RTE) communication profile (CP) and related network components based
on the IEC 61158 series (Type 26), ISO/IEC/IEEE 8802-3 and other standards.
For each RTE communication profile, this document also specifies the relevant RTE
performance indicators and the dependencies between these RTE performance indicators.
NOTE 1 All CPs are based on standards or draft standards or International Standards published by the IEC or on
standards or International Standards established by other standards bodies or open standards processes.
NOTE 2 The RTE communication profile uses ISO/IEC/IEEE 8802-3 communication networks and its related
network components and in some cases amend those standards to obtain RTE features.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
NOTE All parts of the IEC 61158 series, as well as the IEC 61784-1 series and the IEC 61784-2 series, are
maintained simultaneously. Cross-references to these documents within the text therefore refer to the editions as
dated in this list of normative references.
IEC 61158 (all parts), Industrial communication networks – Fieldbus specifications
IEC 61158-5-26:2023, Industrial communication networks – Fieldbus specifications – Part 5-26:
Application layer service definition – Type 26 elements
IEC 61158-6-26:2023, Industrial communication networks – Fieldbus specifications – Part 6-26:
Application layer protocol specification – Type 26 elements
IEC 61784-2-0:2023, Industrial networks – Profiles – Part 2-0: Additional real-time fieldbus
profiles based on ISO/IEC/IEEE 8802-3 – General concepts and terminology
IEC 61784-5-21, Industrial communication networks – Profiles – Part 5-21: Installation of
fieldbuses – Installation profiles for CPF 21
IEC 61918, Industrial communication networks – Installation of communication networks in
industrial premises
ISO/IEC/IEEE 8802-3, Telecommunications and exchange between information technology
systems – Requirements for local and metropolitan area networks – Part 3: Standard for
Ethernet

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IEC 61784-2-21:2023 © IEC 2023 – 7 –
IEEE Std 802-2014, IEEE Standard for Local and Metropolitan Area Networks: Overview and
Architecture
IEEE Std 802.1AB-2016, IEEE Standard for Local and metropolitan area networks – Station and
Media Access Control Connectivity Discovery
IEEE Std 802.1AS-2020, IEEE standard for Local and metropolitan area networks – Timing and
Synchronization for Time-Sensitive Applications in Bridged Local Area Networks
IEEE Std 802.1Q-2018, IEEE Standard for Local and metropolitan area networks – Bridges and
Bridged Networks
IETF RFC 768, J. Postel, User Datagram Protocol, August 1980, available at
https://www.rfc-editor.org/info/rfc768 [viewed 2022-02-18]
IETF RFC 791, J. Postel, Internet Protocol, September 1981, available at
https://www.rfc-editor.org/info/rfc791 [viewed 2022-02-18]
IETF RFC 792, J. Postel, Internet Control Message Protocol, September 1981, available at
https://www.rfc-editor.org/info/rfc792 [viewed 2022-02-18]
IETF RFC 793, J. Postel, Transmission Control Protocol, September 1981, available at
https://www.rfc-editor.org/info/rfc793 [viewed 2022-02-18]
IETF RFC 796, J. Postel, Address mappings, September 1981, available at
https://www.rfc-editor.org/info/rfc796 [viewed 2022-02-18]
IETF RFC 826, D. Plummer, An Ethernet Address Resolution Protocol: Or Converting Network
Protocol Addresses to 48.bit Ethernet Address for Transmission on Ethernet Hardware,
November 1982, available at https://www.rfc-editor.org/info/rfc826 [viewed 2022-02-18]
IETF RFC 894, C. Hornig, A Standard for the Transmission of IP Datagrams over Ethernet, April
1984, available at https://www.rfc-editor.org/info/rfc894 [viewed 2022-02-18]
IETF RFC 919, J.C. Mogul, Broadcasting Internet Datagrams, October 1984, available at
https://www.rfc-editor.org/info/rfc919 [viewed 2022-02-18]
IETF RFC 922, J.C. Mogul, Broadcasting Internet datagrams in the presence of subnets,
October 1984, available at https://www.rfc-editor.org/info/rfc922 [viewed 2022-02-18]
IETF RFC 950, J.C. Mogul and J. Postel, Internet Standard Subnetting Procedure, August 1985,
available at https://www.rfc-editor.org/info/rfc950 [viewed 2022-02-18]
3 Terms, definitions, abbreviated terms, acronyms, and conventions
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61784-2-0,
ISO/IEC/IEEE 8802-3, IEEE Std 802-2014, IEEE Std 802.1AB-2016, IEEE Std 802.1AS-2020
and IEEE Std 802.1Q-2018 apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp

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– 8 – IEC 61784-2-21:2023 © IEC 2023
3.2 Abbreviated terms and acronyms
For the purposes of this document, abbreviated terms and acronyms defined in IEC 61784-2-0
and the following apply.
ARP Address Resolution Protocol (see IETF RFC 826)
CP Communication Profile [according to IEC 61784-1-0]
CPF Communication Profile Family [according to IEC 61784-1-0]
FA Factory Automation
FCS Frame check sequence
ICMP Internet Control Message Protocol (see IETF RFC 792)
IETF Internet Engineering Task Force
IP Internet Protocol (see IETF RFC 791)
LLDP Link Layer Discovery Protocol (see IEEE Std 802.1AB-2016)
NoS Number of Switches
Phy PHY Physical layer entity sublayer (see ISO/IEC/IEEE 8802-3)
PI Performance indicator
RSTP Rapid Spanning Tree Algorithm and Protocol (see IEEE Std 802.1Q-2018)
TCP Transmission Control Protocol (see IETF RFC 793)
UDP User Datagram Protocol (see IETF RFC 768)
3.3 Symbols
For the purposes of this document, symbols defined in IEC 61784-2-0 and Table 1 apply.
NOTE Definitions of symbols in this Subclause 3.3 do not use the italic font, as they are already identified as
symbols.

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IEC 61784-2-21:2023 © IEC 2023 – 9 –
Table 1 – CPF 21 symbols
Symbol Definition Unit
BW Total bandwidth in %, and the 100 % is Erate %
BWnrt Non-RTE bandwidth %
BWrte Bandwidth used for the RTE communications %
Cd µs
Signal propagation delay on the cable segment #i
i
Clen m
Cable length of a cable segment #i
i
Cpd Signal propagation delay on the cabling path between sending and receiving end-stations µs
µs/m
Cε
Cable prppagation delay constant per meter on the cable segment #i
i
DT Delivery time µs
DVct Total volume of the cyclic-data sent out by all end-stations Octets
Erate Ethernet data-transmission rate Mbit/s
NoC Number of cable segments between sending and receiving end-stations
NoS Number of switches (including Hub) between sending and receiving end-stations
STTsr Sender and Receiver stack traversal time including Phy, MAC, IP, UDP or TCP and FAL µs
i
processing time of end-station #i
Tct Sum total of the transmission time of all Cyclic-data frames by all end-stations µs
Tctn
Total number of Cyclic-data frames sent out by end-station #i
i
Tcs Sum total of the transmission time up to the permissible count of general Ethernet frame µs
including the general-purpose-server-command transmission
Tms Sum total of the transmission time up to the permissible count of message-data frame µs
sporadically requested during one Tttkr time period
Tnn The total number of nodes participating in the logical ring
Trmt Refresh-cycle-measurement time which is the elapsed time period from the time after µs
obtaining the token by an end-station until the time the end-station obtains the token once
again
TRrte Throughput RTE Octets/s
Ttf Packet frame transmission time µs
Tsw Latency of the switch (including Hub) #i µs
i
Tsw Sum total of the switch (including Hub) latencies on the connection path between sending µs
and receiving end-stations
Ttk Transmission time of the token frames out of all end-stations including the inter-frame µs
space time for sending out the token frame immediately after sending out the final-cyclic-
data frame
Ttkif Inter-frame space time for sending out the token frame immediately after sending out the µs
i
final-cyclic-data frame by end-station #i
Tttkr Target-token-rotation time µs

3.4 Conventions
For the purposes of this document, the conventions defined in IEC 61784-2-0 apply.

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1
4 CPF 21 (FL-net ) – RTE communication profiles
4.1 General overview
Communication Profile Family 21 defines the communication profile based on IEC 61158-5-26
and IEC 61158-6-26 which corresponds to the communication systems commonly known as
FL-net.
• Profile 21/1 (FL-net)
This profile constitutes an FL-net communication system with star topology. It contains a
selection of AL services and protocol definitions from IEC 61158-5-26 and IEC 61158-6-26.
Table 2 shows the overview of FL-net profile set.
Table 2 – CPF 21: Overview of profile sets
Layer Profile 21/1
Application IEC 61158-5-26, IEC 61158-6-26
Data-link a set of the off-the-shelf protocol suite as follows:
IETF RFC 768(UDP), IETF RFC 793(TCP)
IETF RFC 791(IP)
IETF RFC 919, IETF RFC 922
IETF RFC 792, IETF RFC 950
IETF RFC 894 / ISO/IEC/IEEE 8802-3 Ethernet MAC
IETF RFC 826
Physical ISO/IEC/IEEE 8802-3 Phy

4.2 CP 21/1
4.2.1 Physical layer
The physical layer of 100 Mbit/s and 1 000 Mbit/s shall be according to ISO/IEC/IEEE 8802-3.
Connectors, cables and the installation guideline are specified in IEC 61784-5-21 and
IEC 61918.
4.2.2 Data-link layer
4.2.2.1 Overview
Functions of the intermediate OSI layers, layers 3 through 6, are consolidated into the
IEC 61158 data-link layer of a Type 26 fieldbus.
Three kinds of Type 26 data transmission services are defined in IEC 61158-5-26 and
IEC 61158-6-26, which are Cyclic-data transmission (CT), Message-data transmission (MT) and
General-purpose-server-command transmission (CS).
The Cyclic-data transmission and the Message-data transmission are performed as message
transfer services through UDP communication channe
...