IEC 61158-6-27:2023

IEC 61158-6-27 ®
Edition 1.0 2023-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial communication networks – Fieldbus specifications –
Part 6-27: Application layer protocol specification – Type 27 elements

Réseaux de communication industriels – Spécifications des bus de terrain –
Partie 6-27: Spécification du protocole de la couche application – Éléments de
type 27
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni
utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et
les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Secretariat Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC Products & Services Portal - products.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always have
committee, …). It also gives information on projects, replaced access to up to date content tailored to your needs.
and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 300 terminological entries in English
details all new publications released. Available online and once
and French, with equivalent terms in 19 additional languages.
a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or need
further assistance, please contact the Customer Service
Centre: sales@iec.ch.
A propos de l'IEC
La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications IEC
Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la
plus récente, un corrigendum ou amendement peut avoir été publié.

Recherche de publications IEC - Découvrez notre puissant moteur de recherche et consultez
webstore.iec.ch/advsearchform gratuitement tous les aperçus des publications. Avec un
La recherche avancée permet de trouver des publications IEC abonnement, vous aurez toujours accès à un contenu à jour
en utilisant différents critères (numéro de référence, texte, adapté à vos besoins.
comité d’études, …). Elle donne aussi des informations sur les
projets et les publications remplacées ou retirées. Electropedia - www.electropedia.org

Le premier dictionnaire d'électrotechnologie en ligne au monde,
IEC Just Published - webstore.iec.ch/justpublished
avec plus de 22 300 articles terminologiques en anglais et en
Restez informé sur les nouvelles publications IEC. Just
français, ainsi que les termes équivalents dans 19 langues
Published détaille les nouvelles publications parues.
additionnelles. Egalement appelé Vocabulaire
Disponible en ligne et une fois par mois par email.
Electrotechnique International (IEV) en ligne.

Service Clients - webstore.iec.ch/csc
Si vous désirez nous donner des commentaires sur cette
publication ou si vous avez des questions contactez-nous:
sales@iec.ch.
IEC Products & Services Portal - products.iec.ch

IEC 61158-6-27 ®
Edition 1.0 2023-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial communication networks – Fieldbus specifications –

Part 6-27: Application layer protocol specification – Type 27 elements

Réseaux de communication industriels – Spécifications des bus de terrain –

Partie 6-27: Spécification du protocole de la couche application – Éléments de

type 27
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.040 ISBN 978-2-8322-6620-5

– 2 – IEC 61158-6-27:2023 © IEC 2023
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
1.1 General . 10
1.2 Specifications . 10
1.3 Conformance . 11
2 Normative references . 11
3 Terms, definitions, abbreviated terms, symbols and conventions . 12
3.1 Referenced terms and definitions . 12
3.1.1 Terms and definitions from ISO/IEC 7498-1 . 12
3.1.2 Terms and definitions from ISO/IEC 9545 . 12
3.1.3 Terms and definitions from ISO/IEC 8824-1 . 13
3.1.4 Terms and definitions from ISO/IEC 10731 . 13
3.1.5 Terms and definitions from ISO/IEC 19501 . 13
3.2 Additional terms and definitions . 13
3.3 Abbreviations and symbols . 22
3.4 Conventions . 24
3.4.1 General conventions . 24
3.4.2 PDU data type conventions . 24
3.4.3 State machine conventions . 24
4 Abstract syntax . 26
4.1 General . 26
4.2 Basic Data types . 27
4.3 FAL PDU types . 28
4.3.1 General . 28
4.3.2 Top of APDU types: _APDU . 31
4.3.3 PDUs for field system management service . 31
4.3.4 Detailed definitions of _FID-PDUs . 34
4.3.5 PDUs for field device control service . 48
4.3.6 PDUs for message service . 57
4.4 Detailed definitions of _FDCService-PDUs . 58
4.4.1 Enhanced PDU type . 58
4.5 Device profile . 72
5 Transfer syntax . 72
5.1 Concepts . 72
5.2 Encode rules . 73
5.2.1 INTEGER and its subtypes . 73
5.2.2 REAL type and its subtypes . 74
5.2.3 BIT STRING type . 76
5.2.4 OCTET STRING type and IA5String type . 77
5.2.5 NULL type . 77
5.2.6 Structure type and Array type . 77
6 Structure of FAL protocol state machine . 78
7 AP-context state machine (APC SM) . 80
7.1 Overview. 80
7.2 State descriptions . 81

7.3 Triggering events . 81
7.4 Action descriptions at state transitions . 82
8 FAL service protocol machines (FSPM) . 84
8.1 Overview. 84
8.2 RT Protocol Machine (RT PM). 84
8.2.1 Link layer discovery . 84
8.2.2 MAC bridges . 84
8.2.3 Virtual bridges . 105
8.2.4 IP suite . 105
8.2.5 DLL mapping protocol machine (DMPM) . 105
8.3 Field System Management Protocol Machine (FSM PM) . 110
8.3.1 Overview . 110
8.3.2 Discovery and basic configuration . 112
8.3.3 Starting up of system . 115
8.3.4 Sync methods . 144
8.3.5 Plug-and-play entry . 153
8.4 Field Deice Control Protocol Machine (FDC PM) . 154
8.4.1 Protocol overview . 154
8.4.2 Cyclic communication mode . 156
8.4.3 Event driven communication mode . 160
8.4.4 Master Protocol Machine (FDCPM-M) . 161
8.4.5 Slave Protocol Machine (FDCPM-S) . 169
8.4.6 Error procedure summary . 179
8.5 Message Protocol Machine (MSG PM) . 181
8.5.1 Protocol overview . 181
8.5.2 Requester Protocol Machine (MSGPM-RQ) . 183
8.5.3 Responder Protocol Machine (MSGPM-RS) . 186
9 Application relationship protocol machine (ARPM) . 188
9.1 General . 188
9.2 ARPM for FDC ASE . 188
9.2.1 Overview . 188
9.2.2 ARPM for FDC Master (ARPM-FDCM) . 189
9.2.3 ARPM for FDC Slave (ARPM-FDCS) . 196
9.3 ARPM for MSG ASE (ARPM-MSG) . 203
9.3.1 State descriptions . 203
9.3.2 Triggering events . 203
9.3.3 Action descriptions at state transitions . 204
10 DLL mapping protocol machines (DMPMs) . 204
Annex A (informative) Device profile and FDC command sets . 205
Annex B (normative) Virtual memory space and Device Information . 207
B.1 Overview. 207
B.2 Communication Data Object . 207
B.3 Device Information . 208
B.3.1 Device identifier area structure . 208
B.3.2 Detail specifications of device IDs . 209
Annex C (informative) Basic message function . 217
Bibliography . 218

– 4 – IEC 61158-6-27:2023 © IEC 2023
Figure 1 – Encode of Integer subtypes . 73
Figure 2 – Example of transfer of INTEGER value . 74
Figure 3 – Encode of Unsigned subtypes . 74
Figure 4 – Float32 type encode . 75
Figure 5 – Float64 type encode . 75
Figure 6 – Bit field definition example with named bits . 76
Figure 7 – Bit field definition example with field size . 77
Figure 8 – SEQUENCE type encode . 78
Figure 9 – Structure of FAL protocol state machines . 80
Figure 10 – State chart diagram of APC SM . 81
Figure 11 – Master CTC state transition chart . 86
Figure 12 – Slave CTC state transition chart . 96
Figure 13 – Structuring of the protocol machines within the DMPM (bridge) . 106
Figure 14 – SRC state transition chart . 106
Figure 15 – Example of network configuration . 111
Figure 16 – Network initialization procedures . 112
Figure 17 – Neighboring node notification sequence . 113
Figure 18 – Connected node detection sequence . 114
Figure 19 – Example of neighboring node information . 115
Figure 20 – FSMUL state transition chart for the master with SM function . 116
Figure 21 – FSMUL state transition chart for the master without SM function . 129
Figure 22 – FSMUL state transition chart for a slave . 138
Figure 23 – Sequence of SM delay time notification by CDO writing. 145
Figure 24 – Delay measurement sequence (SM: BM) . 147
Figure 25 – Master delay measurement sequence for the BM (SM: master with band
master function (BM)) . 148
Figure 26 – Delay measurement sequence for the master other than the BM (SM: BM). 149
Figure 27 – Delay measurement sequence (SM: S#1) . 151
Figure 28 – Master delay measurement sequence for the BM (SM: S#1) . 152
Figure 29 – Plug-and-play entry sequence . 154
Figure 30 – Example communication cycle of FDC master AP . 156
Figure 31 – Example communication cycle of FDC slave AP . 157
Figure 32 – Synchronous command communication in sync state . 158
Figure 33 – Asynchronous command communication in sync state . 159
Figure 34 – Asynchronous command communication in async state . 160
Figure 35 – Event-driven communication . 161
Figure 36 – State chart diagram of FDCPM-M . 162
Figure 37 – State chart diagram of FDCPM-S . 170
Figure 38 – PDU transmission flow for user message . 182
Figure 39 – PDU transmission flow for one-way message . 183
Figure 40 – State chart diagram of MSGPM-RQ . 184
Figure 41 – State chart diagram of MSGPM-RS . 186
Figure 42 – Example of single transfer process . 188

Figure 43 – Example of dual transfer process . 189
Figure 44 – State chart diagram of ARPM-FDCM . 190
Figure 45 – Statechart diagram of ARPM-FDCS . 196
Figure 46 – Statechart diagram of ARPM-MSG . 203
Figure B.1 – Memory map of virtual memory space . 207
Figure B.2 – Memory map of device ID area . 208

Table 1 – State transition descriptions . 25
Table 2 – Description of state machine elements . 25
Table 3 – Conventions used in state machines . 26
Table 4 – Multicast address . 29
Table 5 – Length_or_type . 29
Table 6 – IPv4 Header . 30
Table 7 – IPv6 Header . 30
Table 8 – UDP Header . 30
Table 9 – Node address . 33
Table 10 – Mapping for Protocol State Machines . 79
Table 11 – State descriptions of APC SM . 81
Table 12 – Trigger event descriptions of APC SM . 82
Table 13 – Transitions of APC SM . 83
Table 14 – Master CTC state transition table . 87
Table 15 – Slave CTC state transition table . 96
Table 16 – List of CTC macros . 101
Table 17 – The primitives and parameters for FDC interface issued by FDC . 103
Table 18 – The primitives and parameters for FSM interface issued by CTC . 104
Table 19 – The list of primitives and parameters (FSM source) . 104
Table 20 – The list of primitives and parameters (FSMUL source) . 105
Table 21 – SRC state transition table . 107
Table 22 – List of SRC macros . 108
Table 23 – List of SRC functions . 109
Table 24 – Primitives and parameters for SRC-CTC interface . 110
Table 25 – Send frame primitive and parameters . 110
Table 26 – Receive frame primitives and parameters . 110
Table 27 – Primitives and parameters of repeat select service . 110
Table 28 – FSMUL state transition table for the master with SM function . 117
Table 29 – FSMUL state transition table for the master without SM function . 129
Table 30 – FSMUL state transition table for a slave . 138
Table 31 – List of FSMUL macros . 142
Table 32 – FDC protocol mode . 155
Table 33 – State descriptions of FDCPM-M . 162
Table 34 – Trigger event descriptions of FDCPM-M . 163
Table 35 – Transitions of main SM of FDCPM-M . 164
Table 36 – Transitions of submachine of FDCPM-M . 166

– 6 – IEC 61158-6-27:2023 © IEC 2023
Table 37 – State descriptions of FDCPM-S . 170
Table 38 – Trigger event descriptions of FDCPM-S . 171
Table 39 – Transitions of main SM of FDCPM-S . 172
Table 40 – Transitions of submachine of FDCPM-S . 174
Table 41 – State descriptions of MSGPM-RQ . 184
Table 42 – Trigger event descriptions of MSGPM-RQ . 185
Table 43 – Transitions of MSGPM-RQ . 185
Table 44 – State descriptions of MSGPM-RS . 186
Table 45 – Trigger event descriptions of MSGPM-RS . 187
Table 46 – Transitions of MSGPM-RS . 187
Table 47 – State descriptions of ARPM-FDCM . 191
Table 48 – Trigger event descriptions of ARPM-FDCM . 193
Table 49 – Transitions of main SM of ARPM-FDCM . 193
Table 50 – Transitions of submachine of ARPM-FDCM . 195
Table 51 – State descriptions of ARPM-FDCS . 197
Table 52 – Trigger event descriptions of ARPM-FDCS . 199
Table 53 – Transitions of main SM of ARPM-FDCS . 200
Table 54 – Transitions of submachine of ARPM-FDCS . 201
Table 55 – State descriptions of ARPM-MSG . 203
Table 56 – Trigger event descriptions of ARPM-MSG . 203
Table 57 – Transitions of ARPM-MSG . 204
Table A.1 – Example of registered device profiles . 205
Table A.2 – Example command list of the profile '00'H . 206
Table B.1 – Memory map of CDO area . 207
Table B.2 – Specifications of device IDs . 209
Table C.1 – Example of message command set . 217

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 6-27: Application layer protocol specification –
Type 27 elements
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
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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 the associated protocol type is restricted by its
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 its
intellectual-property-right holders.
NOTE Combinations of protocol types are specified in the IEC 61784 1 series and the IEC 61784 2 series.
IEC 61158‑6‑27 has been prepared by subcommittee 65C: Industrial networks, of IEC technical
committee 65: Industrial-process measurement, control and automation. It is an International
Standard.
– 8 – IEC 61158-6-27:2023 © IEC 2023
The text of this International Standard is based on the following documents:
Draft Report on voting
65C/1205/FDIS 65C/1234/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 61158 series, under the general title Industrial communication
networks – Fieldbus specifications, can be found on the IEC web site.
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.
INTRODUCTION
This document is one of a series produced to facilitate the interconnection of automation system
components. It is related to other standards in the set as defined by the "three-layer" fieldbus
reference model described in IEC 61158-1.
The application protocol provides the application service by making use of the services
available from the data-link or other immediately lower layer. The primary aim of this document
is to provide a set of rules for communication expressed in terms of the procedures to be carried
out by peer application entities (AEs) at the time of communication. These rules for
communication are intended to provide a sound basis for development in order to serve a variety
of purposes:
• as a guide for implementers and designers;
• for use in the testing and procurement of equipment;
• as part of an agreement for the admittance of systems into the open systems environment;
• as a refinement to the understanding of time-critical communications within OSI.
This document is concerned, in particular, with the communication and interworking of sensors,
effectors and other automation devices. By using this document together with other documents
positioned within the OSI or fieldbus reference models, otherwise incompatible systems can
work together in any combination.
The International Electrotechnical Commission (IEC) draws attention to the fact that it is claimed
that compliance with this document may involve the use of a patent. IEC takes no position
concerning the evidence, validity, and scope of this patent right.
The holder of this patent right has assured IEC that s/he is willing to negotiate licences under
reasonable and non-discriminatory terms and conditions with applicants throughout the world.
In this respect, the statement of the holder of this patent right is registered with IEC. Information
may be obtained from the patent database available at patents.iec.ch.
Attention is drawn to the possibility that some of the elements of this document may be the
subject of patent rights other than those in the patent database. IEC shall not be held
responsible for identifying any or all such patent rights.

– 10 – IEC 61158-6-27:2023 © IEC 2023
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 6-27: Application layer protocol specification –
Type 27 elements
1 Scope
1.1 General
The Fieldbus Application Layer (FAL) provides user programs with a means to access the
fieldbus communication environment. In this respect, the FAL can be viewed as a "window
between corresponding application programs."
This part of IEC 61158 provides common elements for basic time-critical and non-time-critical
messaging communications between application programs in an automation environment and
material specific to Type 27 fieldbus. The term "time-critical" is used to represent the presence
of a time-window, within which one or more specified actions are required to be completed with
some defined level of certainty. Failure to complete specified actions within the time window
risks failure of the applications requesting the actions, with attendant risk to equipment, plant
and possibly human life.
This document defines in an abstract way the externally visible behavior provided by the
Type 27 fieldbus application layer in terms of
• the abstract syntax defining the application layer protocol data units conveyed between
communicating application entities,
• the transfer syntax defining the application layer protocol data units conveyed between
communicating application entities,
• the application context state machines defining the application service behavior visibly
between communicating application entities, and
• the application relationship state machines defining the communication behavior visibly
between communicating application entities.
The purpose of this document is to define the protocol provided to
• define the representation-on-wire of the service primitives defined in IEC 61158-5-27, and
• define the externally visible behavior associated with their transfer.
This document specifies the protocol of the Type 27 fieldbus application layer, in conformance
with the OSI Basic Reference Model (ISO/IEC 7498-1) and the OSI Application Layer Structure
(ISO/IEC 9545).
1.2 Specifications
The principal objective of this document is to specify the syntax and behavior of the application
layer protocol that conveys the application layer services defined in IEC 61158-5-27.
A secondary objective is to provide migration paths from previously existing industrial
communications protocols. It is this latter objective which gives rise to the diversity of protocols
standardized in IEC 61158-6 series.

1.3 Conformance
This document does not specify individual implementations or products, nor does it constrain
the implementations of application layer entities within industrial automation systems.
Conformance is achieved through implementation of this application layer protocol specification.
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 61158-5-27:2023, Industrial communication networks – Fieldbus specifications – Part 5-27:
Application layer service definition – Type 27 elements
ISO/IEC 646, Information technology – ISO 7-bit coded character set for information
interchange
ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference
Model – Part 1: The Basic Model
ISO/IEC 9545, Information technology – Open Systems Interconnection – Application Layer
structure
ISO/IEC 9899, Information technology – Programming languages – C
ISO/IEC 10731, Information technology – Open Systems Interconnection – Basic Reference
Model – Conventions for the definition of OSI services
ISO/IEC 19501:2005, Information technology – Open Distributed Processing – Unified Modeling
Language (UML) Version 1.4.2
ISO/IEC/IEEE 60559:2020, Information technology – Microprocessor Systems – Floating-Point
arithmetic
ISO/IEC/IEEE 8802-3, Telecommunications and exchange between information technology
systems − Requirements for local and metropolitan area networks − Part 3: Standard for
Ethernet
IEEE Std 802.1D, IEEE Standards for local and metropolitan area networks – Media Access
Control (MAC) Bridges
IEEE Std 802.1Q, IEEE Standards for local and metropolitan area networks – Bridges and
Bridged Networks
IEEE Std 802.1AB, IEEE Standards for Local and Metropolitan Area Networks: Station and
Media Access Control Connectivity Discovery
IEEE Std 802.1AS, IEEE Standards for Local and Metropolitan Area Networks: Timing and
Synchronization for Time-Sensitive Applications in Bridged Local Area Networks

– 12 – IEC 61158-6-27:2023 © IEC 2023
IETF RFC 768, J. Postel, "User Datagram Protocol", August 1980, available at editor.org/info/rfc768> [viewed 2022-09-16]
IETF RFC 791, J. Postel, "Internet Protocol", September 1981, available at editor.org/info/rfc791> [viewed 2022-09-16]
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 [viewed 2022-09-16]
IETF RFC 1112, S.E. Deering, "Host Extensions for IP Multicasting", August 1989, available at
[viewed 2022-09-16]
IETF RFC 2460, S. Deering and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification",
December 1998, available at [viewed 2022-09-16]
3 Terms, definitions, abbreviated terms, symbols and conventions
For the purposes of this document, the following terms, definitions, symbols, abbreviated terms
and conventions apply.
ISO and IEC maintain terminology 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
3.1 Referenced terms and definitions
3.1.1
...