EN IEC 61158-6-21:2019

Industrial communication networks - Fieldbus specifications - Part 6-21: Application layer protocol specification - Type 21 elements

IEC 61158-6-21:2019 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 2 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 International Standard specifies interactions between remote applications and defines the externally visible behavior provided by the Type 2 fieldbus application layer. The purpose of this document is to define the protocol provided to a) define the wire-representation of the service primitives defined in this document, and b) define the externally visible behavior associated with their transfer. This document specifies the protocol of the Type 2 fieldbus application layer, in conformance with the OSI Basic Reference Model (ISO/IEC 7498-1) and the OSI application layer structure (ISO/IEC 9545). This second edition includes the following significant technical changes with respect to the previous edition: - added WriteAndRead service; - miscellaneous editorial corrections.

Industrielle Kommunikationsnetze - Feldbusse - Teil 6-21: Protokollspezifikation des Application Layer (Anwendungsschicht) - Typ 21-Elemente

Réseaux de communication industriels - Spécifications des bus de terrain - Partie 6-21: Spécification du protocole de la couche application - Eléments de type 21

L’IEC 61158-6-21:2019 appartient à une série élaborée pour faciliter l’interconnexion des composants des systèmes d’automatisation. Elle est liée à d'autres normes de la série telle que définie par le modèle de référence des bus de terrain "à trois couches" décrit dans l’IEC 61158‑1. La présente Norme internationale contient des éléments spécifiques au protocole de communication de Type 21.

Industrijska komunikacijska omrežja - Specifikacije za procesna vodila - 6-21. del: Specifikacija protokola na aplikacijski ravni - Elementi tipa 21 (IEC 61158-6-21:2019)

Ta dokument spada v skupino standardov, namenjenih za lažje medsebojno povezovanje sestavnih delov avtomatizacijskega sistema. Povezan je z drugimi standardi v sklopu, kakor je opredeljeno s trinivojskim referenčnim modelom procesnih vodil iz standarda IEC 61158-1. Ta mednarodni standard vsebuje material, specifičen za komunikacijski protokol tipa 21.

General Information

• Status: Published
• Publication Date: 22-Aug-2019
• Withdrawal Date: 24-Jul-2022
• ICS: 25.040.40 - Industrial process measurement and control
• ICS: 35.100.70 - Application layer
• ICS: 35.110 - Networking
• Technical Committee: CLC/TC 65X - Industrial-process measurement, control and automation
• Drafting Committee: IEC/SC 65C - IEC_SC_65C
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 23-Aug-2019
• Completion Date: 23-Aug-2019
• Ref Project: SIST EN IEC 61158-6-21:2019 - Industrial communication networks - Fieldbus specifications - Part 6-21: Application layer protocol specification - Type 21 elements (IEC 61158-6-21:2019)

Relations

• Replaces: EN 61158-6-21:2012 - Industrial communication networks - Fieldbus specifications - Part 6-21: Application layer protocol specification - Type 21 elements
• Effective Date: 23-Jan-2023

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-2019
Nadomešča:
SIST EN 61158-6-21:2012
Industrijska komunikacijska omrežja - Specifikacije za procesna vodila - 6-21. del:
Specifikacija protokola na aplikacijski ravni - Elementi tipa 21 (IEC 61158-6-
21:2019)
Industrial communication networks - Fieldbus specifications - Part 6-21: Application layer
protocol specification - Type 21 elements (IEC 61158-6-21:2019)
Industrielle Kommunikationsnetze - Feldbusse - Teil 6-21: Protokollspezifikation des
Application Layer (Anwendungsschicht) - Typ 21-Elemente (IEC 61158-6-21:2019)
Réseaux de communication industriels - Spécifications des bus de terrain - Partie 6-21:
Spécification du protocole de la couche application - Eléments de type 21 (IEC 61158-6-
21:2019)
Ta slovenski standard je istoveten z: EN IEC 61158-6-21:2019
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
35.100.70 Uporabniški sloj Application layer
35.110 Omreževanje Networking
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61158-6-21

NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2019
ICS 25.040.40; 35.100.70; 35.110 Supersedes EN 61158-6-21:2012 and all of its
amendments and corrigenda (if any)
English Version
Industrial communication networks - Fieldbus specifications -
Part 6-21: Application layer protocol specification - Type 21
elements
(IEC 61158-6-21:2019)
Réseaux de communication industriels - Spécifications des Industrielle Kommunikationsnetze - Feldbusse - Teil 6-21:
bus de terrain - Partie 6-21: Spécification du protocole de la Protokollspezifikation des Application Layer
couche application - Eléments de type 21 (Anwendungsschicht) - Typ 21-Elemente
(IEC 61158-6-21:2019) (IEC 61158-6-21:2019)
This European Standard was approved by CENELEC on 2019-07-25. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61158-6-21:2019 E

European foreword
The text of document 65C/948/FDIS, future edition 2 of IEC 61158-6-21, prepared by SC 65C
"Industrial networks" of IEC/TC 65 "Industrial-process measurement, control and automation" was
submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2020-04-25
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2022-07-25
document have to be withdrawn
This document supersedes EN 61158-6-21:2012 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice
The text of the International Standard IEC 61158-6-21:2019 was approved by CENELEC as a
European Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards
indicated:
IEC 61158-1:2019 NOTE Harmonized as EN IEC 61158-1:2019 (not modified)
IEC 61784-2:2019 NOTE Harmonized as EN IEC 61784-2:2019 (not modified)

Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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 1  Where an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 61158-3-21 2019 Industrial communication networks - Fieldbus EN IEC 61158-3-21 2019
specifications - Part 3-21: Data-link layer
service definition - Type 21 elements
IEC 61158-4-21 2019 Industrial communication networks - Fieldbus EN IEC 61158-4-21 2019
specifications - Part 4-21: Data-link layer
protocol specification - Type 21 elements
IEC 61158-5-21 2019 Industrial communication networks - Fieldbus EN IEC 61158-5-21 2019
specifications - Part 5-21: Application layer
service definition - Type 21 elements
ISO/IEC 7498-1 -  Information technology - Open Systems - -
Interconnection - Basic Reference Model: The
Basic Model
Information technology - Telecommunications
ISO/IEC/IEEE -  - -
and information exchange between systems -
8802-3
Local and metropolitan area networks - Specific
requirements - Part 3: Standard for Ethernet
ISO/IEC 8822 -  Information technology - Open Systems - -
Interconnection - Presentation service definition
ISO/IEC 8824-1 -  Information technology - Abstract Syntax - -
Notation One (ASN.1): Specification of basic
notation
ISO/IEC 9545 -  Information technology - Open Systems - -
Interconnection - Application Layer structure
ISO/IEC 10731 -  Information technology - Open Systems - -
Interconnection - Basic Reference Model -
Conventions for the definition of OSI services
ISO/IEC 9899 -  Information technology - Programming - -
languages - C
IEEE 754 2008 IEEE Standard for Binary Floating-Point - -
Arithmetic
IEC 61158-6-21 ®
Edition 2.0 2019-06
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –

Part 6-21: Application layer protocol specification – Type 21 elements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.040.40; 35.100.70; 35.110 ISBN 978-2-8322-7013-4

– 2 – IEC 61158-6-21:2019 © IEC 2019
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
1.1 General . 9
1.2 Overview. 9
1.3 Specifications . 9
1.4 Conformance . 10
2 Normative references . 10
3 Terms, definitions, symbols, abbreviations and conventions . 10
3.1 Terms and definitions from other ISO/IEC standards . 11
3.1.1 ISO/IEC 7498-1 terms . 11
3.1.2 ISO/IEC 8822 terms . 11
3.1.3 ISO/IEC 8824-1 terms . 11
3.1.4 ISO/IEC 9545 terms . 11
3.2 Other terms and definitions . 11
3.3 Abbreviations and symbols . 17
3.4 Conventions . 18
3.4.1 General conventions . 18
3.4.2 Convention for the encoding of reserved bits and octets . 18
3.4.3 Conventions for the common coding of specific field octets . 18
3.4.4 Conventions for APDU abstract syntax definitions . 19
3.4.5 Conventions for APDU transfer syntax definitions . 19
3.4.6 Conventions for AE state machine definitions . 20
4 FAL syntax description . 21
4.1 General . 21
4.2 FAL-AR PDU abstract syntax . 21
4.2.1 Top level definition . 21
4.2.2 Confirmed send service . 21
4.2.3 Unconfirmed send service . 21
4.2.4 FalArHeader . 21
4.2.5 InvokeID . 21
4.2.6 ServiceType . 21
4.3 Abstract syntax of PDU body . 22
4.3.1 ConfirmedServiceRequest PDUs . 22
4.3.2 ConfirmedServiceResponse PDUs . 22
4.3.3 UnconfirmedServiceRequest PDUs . 22
4.3.4 Error information . 22
4.4 Protocol data units (PDUs) for application service elements (ASEs) . 23
4.4.1 PDUs for Application process ASE . 23
4.4.2 PDUs for Service data object ASE . 25
4.4.3 PDUs for Process data object ASE . 28
5 Transfer Syntax . 28
5.1 Overview of encoding. 28
5.2 APDU header encoding . 29
5.2.1 Encoding of FalArHeader field . 29
5.2.2 Encoding of InvokeID Field . 29

IEC 61158-6-21:2019 © IEC 2019 – 3 –
5.2.3 Encoding of Type field . 29
5.3 APDU body encoding . 30
5.3.1 General . 30
5.4 Encoding of Data types . 30
5.4.1 General description of data types and encoding rules . 30
5.4.2 Transfer syntax for bit sequences . 30
5.4.3 Encoding of a Boolean value . 31
5.4.4 Encoding of an unsigned integer value . 31
5.4.5 Encoding of a signed integer . 31
5.4.6 Encoding of a floating point value .
...