EN IEC 61158-5-4:2023

Industrial communication networks - Fieldbus specifications - Part 5-4: Application layer service definition - Type 4 elements

IEC 61158-5-4:2023 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 4 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.

Industrielle Kommunikationsnetze - Feldbusse - Teil 5-4: Dienstfestlegungen des Application Layer (Anwendungsschicht) - Typ 4-Elemente

Réseaux de communication industriels - Spécifications des bus de terrain - Partie 5-4: Définition des services de la couche application – Eléments de type 4

L'IEC 61158-5-4:2023 fournit des éléments communs pour les communications prioritaires ou non entre des programmes d’application dans un environnement et avec un matériel d’automatisation spécifiques aux bus de terrain de type 4. Le terme "prioritaire" signale l’existence d’une fenêtre temporelle dans laquelle une ou plusieurs actions spécifiées doivent être réalisées, avec un niveau de certitude défini. Si les actions spécifiées ne sont pas réalisées dans la fenêtre temporelle, les applications demandant les actions risquent de connaître une défaillance, avec les risques que cela comporte pour les équipements, les installations et éventuellement la vie humaine.

Industrijska komunikacijska omrežja - Specifikacije za procesna vodila - 5-4. del: Definicija opravil na aplikacijski ravni - Elementi tipa 4 (IEC 61158-5-4:2023)

Aplikacijska raven procesnih vodil (FAL) uporabniškim programom omogoča dostop do komunikacijskega okolja procesnih vodil. Glede na to je mogoče aplikacijsko raven procesnih vodil šteti za »okno med ustreznimi aplikacijami«.
Ta del standarda IEC 61158 določa skupne elemente za osnovne časovno kritične in časovno nekritične sporočilne komunikacije med aplikacijami v avtomatizacijskem okolju ter material, specifičen za procesna vodila tipa 4. Izraz »časovno kritičen« se uporablja za predstavitev prisotnosti časovnega okna, v okviru katerega se zahteva dokončanje enega ali več opredeljenih dejanj z določeno stopnjo gotovosti. Zaradi neuspešnega dokončanja opredeljenih dejanj v časovnem oknu je možna odpoved aplikacij, ki zahtevajo dejanja, pri čemer so ogroženi oprema, obrat in morda človeška življenja.
Ta dokument na abstrakten način določa na zunaj vidno opravilo, ki ga zagotavlja aplikacijska raven procesnih vodil tipa 4 v smislu:
– abstraktnega modela za določanje aplikacijskih virov (objektov), ki ga lahko upravljajo uporabniki prek opravila aplikacijske ravni procesnih vodil;
– primitivnih dejanj in dogodkov opravila;
– parametrov, povezanih z vsakim primitivnim dejanjem in dogodkom, ter obliko, ki jo prevzamejo; in
– medsebojnih povezav med temi dejanji in dogodki ter njihovimi veljavnimi zaporedji.
Namen tega dokumenta je opredeliti opravila, ki se zagotavljajo za:
– uporabnika aplikacijske ravni procesnih vodil na meji med uporabniško in aplikacijsko ravnjo referenčnega modela procesnega vodila, in
– upravljanje sistemov na meji med aplikacijsko ravnjo in upravljanjem sistemov za referenčni model procesnega vodila.
Ta dokument določa strukturo in opravila aplikacijske ravni procesnih vodil tipa 4 v skladu z osnovnim referenčnim modelom OSI (ISO/IEC 7498-1) ter strukturo aplikacijske ravni OSI (ISO/IEC 9545).
Opravila in protokole aplikacijske ravni procesnih vodil zagotavljajo aplikacijski osebki (AE) aplikacijske ravni procesnih vodil znotraj aplikacijskih procesov. Aplikacijski osebek aplikacijske ravni procesnih vodil sestavljata sklop objektno usmerjenih aplikacijskih opravilnih elementov (ASE) in osebek za upravljanje ravni (LME), ki upravlja aplikacijski osebek. Aplikacijski opravilni elementi zagotavljajo komunikacijska opravila, ki delujejo na sklopu povezanih razredov objektov aplikacijskega procesa (APO). Med aplikacijske opravilne elemente aplikacijske ravni procesnih vodil spada aplikacijski opravilni element za upravljanje, ki zagotavlja skupen sklop opravil za upravljanje primerkov razredov aplikacijske ravni procesnih vodil.
Čeprav ta opravila določajo način izdajanja ter dostavljanja zahtev in odzivov z vidika aplikacij, ne zajemajo specifikacije v zvezi s tem, kako naj se nanje odzovejo aplikacije, ki te zahteve in odzive oddajajo. To pomeni, da vedenjski vidiki aplikacij niso opredeljeni; opredeljena je le definicija zahtev in odzivov, ki jih lahko pošiljajo/prejemajo. Tako se uporabnikom aplikacijske ravni procesnih vodil omogoči večja prilagodljivost pri standardizaciji takega vedenja objektov. Poleg teh opravil so v tem dokumentu opredeljena tudi nekatera podporna opravila, da se omogoči dostop do aplikacijske ravni procesnih vodil za nadzorovanje nekaterih vidikov njenega delovanja.

General Information

• Status: Published
• Publication Date: 11-May-2023
• 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
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 12-May-2023
• Completion Date: 12-May-2023
• Ref Project: SIST EN IEC 61158-5-4:2023 - Industrial communication networks - Fieldbus specifications - Part 5-4: Application layer service definition - Type 4 elements (IEC 61158-5-4:2023)

Relations

• Replaces: EN IEC 61158-5-4:2019 - Industrial communication networks - Fieldbus specifications - Part 5-4: Application layer service definition - Type 4 elements
• Effective Date: 11-Apr-2023

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-2023
Nadomešča:
SIST EN IEC 61158-5-4:2019
Industrijska komunikacijska omrežja - Specifikacije za procesna vodila - 5-4. del:
Definicija opravil na aplikacijski ravni - Elementi tipa 4 (IEC 61158-5-4:2023)
Industrial communication networks - Fieldbus specifications - Part 5-4: Application layer
service definition - Type 4 elements (IEC 61158-5-4:2023)
Industrielle Kommunikationsnetze - Feldbusse - Teil 5-4: Dienstfestlegungen des
Application Layer (Anwendungsschicht) - Typ 4-Elemente (IEC 61158-5-4:2023)
Réseaux de communication industriels - Spécifications des bus de terrain - Partie 5-4:
Définition des services de la couche application Eléments de type 4 (IEC 61158-5-
4:2023)
Ta slovenski standard je istoveten z: EN IEC 61158-5-4:2023
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 61158-5-4

NORME EUROPÉENNE
EUROPÄISCHE NORM May 2023
ICS 25.040.40; 35.100.70; 35.110 Supersedes EN IEC 61158-5-4:2019
English Version
Industrial communication networks - Fieldbus specifications -
Part 5-4: Application layer service definition - Type 4 elements
(IEC 61158-5-4:2023)
Réseaux de communication industriels - Spécifications des Industrielle Kommunikationsnetze - Feldbusse - Teil 5-4:
bus de terrain - Partie 5-4: Définition des services de la Dienstfestlegungen des Application Layer
couche application - Eléments de type 4 (Anwendungsschicht) - Typ 4-Elemente
(IEC 61158-5-4:2023) (IEC 61158-5-4:2023)
This European Standard was approved by CENELEC on 2023-04-28. 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,
Türkiye 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
© 2023 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61158-5-4:2023 E

European foreword
The text of document 65C/1203/FDIS, future edition 4 of IEC 61158-5-4, 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 EN IEC 61158-5-4:2023.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2024-01-28
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2026-04-28
document have to be withdrawn
This document supersedes EN IEC 61158-5-4:2019 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.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61158-5-4:2023 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 standard indicated:
IEC 61158-1 NOTE Approved as EN IEC 61158-1
IEC 61158-2 NOTE Approved as EN IEC 61158-2
IEC 61784-1 (series) NOTE Approved as EN IEC 61784-1 (series)
IEC 61784-2 (series) NOTE Approved as EN IEC 61784-2 (series)
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.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 61158-3-4 2023 Industrial communication networks - Fieldbus - -
specifications - Part 3-4: Data-link layer service
definition - Type 4 elements
IEC 61158-4-4 2023 Industrial communication networks - Fieldbus - -
specifications - Part 4-4: Data-link layer protocol
specification - Type 4 elements
IEC 61158-6-4 2023 Industrial communication networks - Fieldbus - -
specifications - Part 6-4: Application layer protocol
specification - Type 4 elements
ISO/IEC 7498-1 - Information technology - Open Systems - -
Interconnection - Basic reference model: The basic
model
ISO/IEC 7498-3 - Information technology - Open Systems - -
Interconnection - Basic reference model: Naming
and addressing
ISO/IEC 8822 - Information technology - Open Systems - -
Interconnection - Presentation service definition
ISO/IEC 8824-1 - Information technology - Abstract Syntax Notation - -
One (ASN.1) - Part 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 60559 - Information technology - Microprocessor Systems - - -
Floating-Point arithmetic
IEC 61158-5-4 ®
Edition 4.0 2023-03
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 5-4: Application layer service definition – Type 4 elements
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.040.40; 35.100.70; 35.110 ISBN 978-2-8322-6572-7
– 2 – IEC 61158-5-4:2023 © IEC 2023
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
1.1 General . 7
1.2 Specifications . 8
1.3 Conformance . 8
2 Normative references . 8
3 Terms, definitions, symbols, abbreviated terms and conventions . 9
3.1 ISO/IEC 7498-1 terms . 9
3.2 ISO/IEC 8822 terms . 9
3.3 ISO/IEC 9545 terms . 10
3.4 ISO/IEC 8824-1 terms . 10
3.5 Fieldbus data-link layer terms . 10
3.6 Fieldbus application layer specific definitions . 10
3.7 Abbreviations and symbols . 16
3.8 Conventions . 17
3.8.1 Overview . 17
3.8.2 General conventions . 18
3.8.3 Conventions for class definitions . 18
3.8.4 Conventions for service definitions . 19
4 Concepts . 20
4.1 Overview. 20
4.2 Architectural relationships . 21
4.2.1 Relationship to the Application Layer of the OSI basic reference model . 21
4.2.2 Relationships to other fieldbus entities. 21
4.3 Fieldbus Application Layer structure . 23
4.3.1 Overview . 23
4.3.2 Fundamental concepts . 23
4.3.3 Fieldbus application processes . 23
4.3.4 Application process objects . 27
4.3.5 Application entities . 29
4.3.6 Fieldbus application service elements . 30
4.3.7 Application relationships . 33
4.4 Fieldbus Application Layer naming and addressing . 35
4.4.1 General . 35
4.4.2 Identifying objects accessed through the FAL . 35
4.4.3 Addressing APs accessed through the FAL. 36
4.5 Architecture summary . 36
4.6 FAL service procedures . 36
4.6.1 FAL confirmed service procedures . 36
4.6.2 FAL unconfirmed service procedures . 37
4.7 Common FAL attributes . 37
4.8 Common FAL service parameters . 38
4.9 APDU size . 39
5 Type 4 communication model specification . 39
5.1 Concepts . 39

IEC 61158-5-4:2023 © IEC 2023 – 3 –
5.1.1 Overview . 39
5.1.2 Application entities . 39
5.1.3 Gateway and routing . 41
5.1.4 Architecture summary . 42
5.1.5 FAL service procedures and time sequence diagrams . 43
5.2 Variable ASE . 45
5.2.1 Variable types. 45
5.2.2 Variable model class specification . 47
5.2.3 Basic variable type specifications . 48
5.2.4 Constructed variable type specifications . 53
5.2.5 Route endpoint ASE . 57
5.2.6 Route endpoint ASE service specification . 60
5.3 Application relationship ASE . 64
5.3.1 Overview . 64
5.3.2 Application relationship class specification . 64
5.3.3 Application relationship ASE service specifications . 66
Bibliography . 71

Figure 1 – Relationship to the OSI basic reference model . 21
Figure 2 – Architectural positioning of the fieldbus Application Layer . 22
Figure 3 – Client/server interactions. 24
Figure 4 – Pull model interactions . 25
Figure 5 – Push model interactions . 26
Figure 6 – APOs services conveyed by the FAL . 28
Figure 7 – Application entity structure . 29
Figure 8 – Example FAL ASEs . 31
Figure 9 – FAL management of objects . 31
Figure 10 – ASE service conveyance . 32
Figure 11 – Defined and established AREPs . 35
Figure 12 – FAL architectural components . 36
Figure 13 – FAL AE . 40
Figure 14 – Summary of the FAL architecture . 42
Figure 15 – FAL service procedure overview . 43
Figure 16 – Time sequence diagram for the confirmed services . 44
Figure 17 – Time sequence diagram for unconfirmed services . 45

Table 1 – REQUEST service parameters . 60
Table 2 – RESPONSE service parameters . 61
Table 3 – Error codes by source . 62
Table 4 – Reserve REP service parameters . 62
Table 5 – Free AREP service parameters . 63
Table 6 – Get REP attribute service parameters . 63
Table 7 – Set REP attribute service parameters . 64
Table 8 – AR send service parameters. 68
Table 9 – AR acknowledge service parameters . 68
Table 10 – AR get attributes service parameters . 69
Table 11 – AR set attributes service parameters . 69

– 4 – IEC 61158-5-4:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 5-4: Application layer service definition –
Type 4 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 IEC 61784-1 series and IEC 61784-2 series.
IEC 61158-5-4 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 fourth edition cancels and replaces the third edition published in 2019. This edition
constitutes a technical revision.

IEC 61158-5-4:2023 © IEC 2023 – 5 –
This edition includes the following significant technical change with respect to the previous
edition:
a) Use of extended data size in an APDU body. This extension is restricted to nodes operating
on a P-NET IP network. There are no technical changes to this sub-part of the standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
65C/1203/FDIS 65C/1244/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 the 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.
– 6 – IEC 61158-5-4:2023 © IEC 2023
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 service is provided by the application protocol making use of the services
available from the data-link or other immediately lower layer. This document defines the
application service characteristics that fieldbus applications and/or system management can
exploit.
Throughout the set of fieldbus standards, the term "service" refers to the abstract capability
provided by one layer of the OSI Basic Reference Model to the layer immediately above. Thus,
the application layer service defined in this document is a conceptual architectural service,
independent of administrative and implementation divisions.

IEC 61158-5-4:2023 © IEC 2023 – 7 –
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 5-4: Application layer service definition –
Type 4 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 4 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 service provided by the Type 4
fieldbus application layer in terms of:
• an abstract model for defining application resources (objects) capable of being manipulated
by users via the use of the FAL service;
• the primitive actions and events of the service;
• the parameters associated with each primitive action and event, and the form which they
take; and
• the interrelationship between these actions and events, and their valid sequences.
The purpose of this document is to define the services provided to:
• the FAL user at the boundary between the user and the application layer of the fieldbus
reference model, and
• Systems Management at the boundary between the application layer and Systems
Management of the fieldbus reference model.
This document specifies the structure and services of the Type 4 fieldbus application layer, in
conformance with the OSI Basic Reference Model (ISO/IEC 7498-1) and the OSI application
layer structure (ISO/IEC 9545).
FAL services and protocols are provided by FAL application-entities (AE) contained within the
application processes. The FAL AE is composed of a set of object-oriented application service
elements (ASEs) and a layer management entity (LME) that manages the AE. The ASEs provide
communication services that operate on a set of related application process object (APO)
classes. One of the FAL ASEs is a management ASE that provides a common set of services
for the management of the instances of FAL classes.

– 8 – IEC 61158-5-4:2023 © IEC 2023
Although these services specify, from the perspective of applications, how request and
responses are issued and delivered, they do not include a specification of what the requesting
and responding applications are to do with them. That is, the behavioral aspects of the
applications are not specified; only a definition of what requests and responses they can
send/receive is specified. This permits greater flexibility to the FAL users in standardizing such
object behavior. In addition to these services, some supporting services are also defined in this
document to provide access to the FAL to control certain aspects of its operation.
1.2 Specifications
The principal objective of this document is to specify the characteristics of conceptual
application layer services suitable for time-critical communications, and thus supplement the
OSI Basic Reference Model in guiding the development of application layer protocols for time-
critical communications.
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 services
standardized as the various Types of IEC 61158, and the corresponding protocols standardized
in in subparts of IEC 61158-6.
This document can be used as the basis for formal application programming interfaces.
Nevertheless, it is not a formal programming interface, and any such interface will need to
address implementation issues not covered by this specification, including
a) the sizes and octet ordering of various multi-octet service parameters, and
b) the correlation of paired request and confirm, or indication and response, primitives.
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.
There is no conformance of equipment to this application layer service definition standard.
Instead, conformance is achieved through implementation of conforming application layer
protocols that fulfill the Type 2 application layer services as defined in this document.
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 IEC 61784-1 series and 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 61158-3-4:2023, Industrial communication networks – Fieldbus specifications – Part 3-4:
Data-link layer service definition – Type 4 elements
IEC 61158-4-4:2023, Industrial communication networks – Fieldbus specifications – Part 4-4:
Data-link layer protocol specification – Type 4 elements
IEC 61158-6-4:2023, Industrial communication networks – Fieldbus specifications – Part 6-4:
Application layer protocol specification – Type 4 elements
ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference
Model – Part 1: The Basic Model

IEC 61158-5-4:2023 © IEC 2023 – 9 –
ISO/IEC 7498-3, Information technology – Open Systems Interconnection – Basic Reference
Model – Part 3: Naming and addressing
ISO/IEC 8822, Information technology – Open Systems Interconnection – Presentation service
definition
ISO/IEC 8824-1, Information technology – Abstract Syntax Notation One (ASN.1) – Part 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 60559, Floating-point arithmetic
3 Terms, definitions, symbols, abbreviated terms and conventions
For the purposes of this document, the following terms, definitions, symbols, abbreviated terms
and conventions 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
3.1 ISO/IEC 7498-1 terms
For the purposes of this document, the following terms as defined in ISO/IEC 7498 1 apply:
a) application entity
b) application process
c) application protocol data unit
d) application service element
e) application entity invocation
f) application process invocation
g) application transaction
h) real open system
i) transfer syntax
3.2 ISO/IEC 8822 terms
For the purposes of this document, the following terms as defined in ISO/IEC 8822 apply:
a) abstract syntax
b) presentation context
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3.3 ISO/IEC 9545 terms
For the purposes of this document, the following terms as defined in ISO/IEC 9545 apply:
a) application-association
b) application-context
c) application context name
d) application-entity-invocation
e) application-entity-type
f) application-process-invocation
g) application-process-type
h) application-service-element
i) application control service element
3.4 ISO/IEC 8824-1 terms
For the purposes of this document, the following terms as defined in ISO/IEC 8824-1 apply:
a) object identifier
b) type
3.5 Fieldbus data-link layer terms
For the purposes of this document, the following terms apply.
a) DL-Time
b) DL-Scheduling-policy
c) DLCEP
d) DLC
e) DLPDU
f) DLSDU
g) DLSAP
h) fixed tag
i) generic tag
j) link
k) network address
l) node address
m) node
n) tag
o) scheduled
p) unscheduled
3.6 Fieldbus application layer specific definitions
For the purposes of this document, the following terms and definitions apply.
3.6.1
application
function or data structure for which data is consumed or produced

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3.6.2
application objects
multiple object classes that manage and provide a run time exchange of messages across the
network and within the network device
3.6.3
application process
part of a distributed application on a network, which is located on one device and unambiguously
addressed
3.6.4
application process identifier
value that distinguishes an application process among multiple application processes used in a
device
3.6.5
application process object
component of an application process that is identifiable and accessible through an FAL
application relationship
Note 1 to entry: Application process object definitions are composed of a set of values for the attributes of their
class (see the definition for Application Process Object Class Definition). Application process object definitions can
be accessed remotely using the services of the FAL Object Management ASE. FAL Object Management services can
be used to load or update object definitions, to read object definitions, and to dynamically create and delete
application objects and their corresponding definitions.
3.6.6
application process object class
class of application process objects defined in terms of the set of their network-accessible
attributes and services
3.6.7
application relationship
cooperative association between two or more application-entity-invocations for the purpose of
exchange of information and coordination of their joint operation
Note 1 to entry: This relationship is activated either by the exchange of application-protocol-data-units or as a result
of preconfiguration activities.
3.6.8
application relationship application service element
application-service-element that provides the exclusive means for establishing and terminating
all application relationships
3.6.9
application relationship endpoint
context and behavior of an application relationship as seen and maintained by one of the
application processes involved in the application relationship
Note 1 to entry: Each application process involved in the application relationship maintains its own application
relationship endpoint.
3.6.10
attribute
description of an externally visible characteristic or feature of an object
Note 1 to entry: The attributes of an object contain information about variable portions of an object. Typically, they
provide status information or govern the operation of an object. Attributes can also affect the behavior of an object.
Attributes are divided into class attributes and instance attributes.

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3.6.11
behavior
indication of how an object responds to particular events
3.6.12
bit-no
number of a bit in a bitstring or an octet
3.6.13
channel
single physical or logical link of an input or output application object of a server to the process
3.6.14
class
set of objects, all of which represent the same kind of system component
Note 1 to entry: A class is a generalisation of an object; a template for defining variables and methods. All objects
in a class are identical in form and behavior, but usually contain different data in their attributes.
3.6.15
class attributes
attribute that is shared by all objects within the same class
3.6.16
class code
unique identifier assigned to each object class
3.6.17
class specific service
service defined by a particular object class to perform a required function which is not performed
by a common service
Note 1 to entry: A class specific object is unique to the object class which defines it.
3.6.18
client
object which uses the services of another (server) object to perform a task
3.6.19
client
initiator of a message to which a server reacts
3.6.20
communication objects
components that manage and provide a run time exchange of messages across the network
EXAMPLES: Connection Manager object, Unconnected Message Manager (UCMM) object, and Message Router
object.
3.6.21
connection
logical binding between application objects that may be within the same or different devices
Note 1 to entry: Connections may be either point-to-point or multipoint.
3.6.22
conveyance path
unidirectional flow of APDUs across an application relationship

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3.6.23
dedicated AR
AR used directly by the FAL User
Note 1 to entry: On Dedicated ARs, only the FAL Header and the user data are transferred.
3.6.24
default DL-address
value 126 as an initial value for DL-address, which has to be changed (e.g. by assignment of a
DL-address via the fieldbus) before operation with a DP-master (class 1)
3.6.25
device
physical hardware connected to the link
Note 1 to entry: A device may contain more than one node.
3.6.26
dynamic AR
AR that requires the use of the AR establishment procedures to place it into an established
state
3.6.27
endpoint
one of the communicating entities involved in a connection
3.6.28
error
discrepancy between a computed, observed or measured value or condition and the specified
or theoretically correct value or condition
3.6.29
error class
general grouping for related error definitions and corresponding error codes
3.6.30
error code
identification of a specific type of error within an error class
3.6.31
event
instance of a change of conditions
3.6.32
FAL subnet
subnetworks composed of one or more data link segments, identified by a subset of the network
address
Note 1 to entry: FAL subnets are permitted to contain bridges but not routers.
3.6.33
FIFO variable
Variable Object class, composed of a set of homogeneously typed elements, where the first
written element is the first element that can be read.
Note 1 to entry: On the fieldbus only one, complete element can be transferred as a result of one service invocation.
3.6.34
frame
deprecated synonym for DLPDU
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3.6.35
interface
shared boundary between two functional units, defined by functional
characteristics, signal characteristics, or other characteristics as appropriate
3.6.36
interface
collection of FAL class attributes and services that represents a
specific view on the FAL class
3.6.37
invocation
act of using a service or other resource of an application process
Note 1 to entry: Each invocation represents a separate thread of control that can be described by its context. Once
the service completes, or use of the resource is released, the invocation ceases to exist. For service invocations, a
service that has been initiated but not yet completed is referred to as an outstanding service invocation. Also for
service invocations, an Invoke ID may be used to unambiguously identify the service invocation and differentiate it
from other outstanding service invocations.
3.6.38
index
address of an object within an application process
3.6.39
instance
actual physical occurrence of an object within a class that identifies one of many objects within
the same object class
EXAMPLE California is an instance of the object class state.
Note 1 to entry: The terms object, instance, and object instance are used to refer to a specific instance.
3.6.40
instance attributes
attribute that is unique to an object instance and not shared by the object class
3.6.41
instantiated
object that has been created in a device
3.6.42
logical device
certain FAL class that abstracts a software component or a firmware component as an
autonomous self-contained facility of an automation device
3.6.43
manufacturer ID
identification of each product manufacturer by a unique number
3.6.44
management information
network-accessible information that supports managing the operation of the fieldbus system,
including the application layer
Note 1 to entry: Managing includes functions such as controlling, monitoring, and diagnosing.
3.6.45
member
piece of an attribute that is structured as an element of an array

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3.6.46
method
a synonym for an operational service which is provided by the server ASE and invoked
by a client
3.6.47
module
hardware or logical component of a physical device
3.6.48
network
set of nodes connected by some type of communication medium, including any intervening
repeaters, bridges, routers and lower-layer gateways
3.6.49
object
abstract representation of a particular component within a device, usually a collection of related
data (in the form of variables) and methods (procedures) for operating on that data that have
clearly defined interface and behavior
3.6.50
object specific service
service unique to the object class which defines it
3.6.51
peer
role of an AR endpoint in which it is capable of acting as both client and server
3.6.52
physical device
automation or other network device
3.6.53
property
general term for descriptive information about an object
3.6.54
provider
source of a data connection
3.6.55
publisher
role of an AR endpoint that transmits APDUs onto the fieldbus for consumption by one or more
subscribers
Note 1 to entry: A publisher is possible aware of the identity or the number of subscribers, or not and it can publish
its APDUs using a dedicated AR.
3.6.56
publishing manager
role of an AR endpoint in which it issues one or more confirmed service request APDUs to a
publisher to requ
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