SIST EN IEC 61158-5-21:2019
(Main)Industrial communication networks - Fieldbus specifications - Part 5-21: Application layer service definition - Type 21 elements (IEC 61158-5-21:2019)
Industrial communication networks - Fieldbus specifications - Part 5-21: Application layer service definition - Type 21 elements (IEC 61158-5-21:2019)
The Fieldbus Application Layer (FAL) provides user programs with a means to access the fieldbus communication environment. In this respect, the FAL can be considered a window between corresponding application programs. This part of IEC 61158 provides the common elements for basic time-critical and non-timecritical messaging communications between application programs in an automation environment as well as material specific to the Type 21 protocol. 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 defines, in an abstract way, the externally visible service provided by the FAL in terms of: a) an abstract model for defining application resources (objects) capable of being manipulated by users via the FAL service; b) the primitive actions and events of the service; c) the parameters associated with each primitive action and event, and the form that they take; d) the interrelationship between these actions and events, and their valid sequences. The purpose of this document is to define the services provided to: a) the FAL-user at the boundary between the user and the application layer of the fieldbus Reference Model; b) systems management at the boundary between the application layer and systems management of the fieldbus Reference Model. This document describes the structure and services of the IEC FAL, in conformance with the OSI Basic Reference Model (ISO/IEC 7498) and the OSI Application layer Structure (ISO/IEC 9545). FAL services and protocols are provided by FAL application entities (AEs) contained in 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 management of the instances of FAL classes. Although these services specify how requests and responses are issued and delivered from the perspective of applications, they do not include a specification of what the requesting and responding applications are to do with them. That is, these services only define what requests and responses applications can send or receive, not the functions of the applications themselves. 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.
Industrielle Kommunikationsnetze - Feldbusse - Teil 5-21: Dienstfestlegungen des Application Layer (Anwendungsschicht) - Typ 21-Elemente (IEC 61158-5-21:2019)
Réseaux de communication industriels- Spécifications des bus de terrain - Partie 5-21 : Définition des services de la couche application - Éléments de type 21 (IEC 61158-5-21:2019)
L’IEC 61158-5-21:2019 fournit les éléments communs pour les communications de base à temps critique et à temps non critique entre des programmes d'application dans un environnement d'automatisation ainsi que le matériau spécifique au protocole de type 21. Le terme "à temps critique" sert à représenter la présence d'une fenêtre temporelle, dans les limites de laquelle il est exigé qu'une ou plusieurs actions spécifiées soient terminées avec un certain niveau défini de certitude. Le manquement à parachever les actions spécifiées dans les limites de la fenêtre temporelle risque d'entraîner la défaillance des applications qui demandent ces actions, avec le risque concomitant pour l'équipement, la centrale et éventuellement pour la vie humaine.
Industrijska komunikacijska omrežja - Specifikacije za procesna vodila - 5-21. del: Definicija opravil na aplikacijski ravni - Elementi tipa 21 (IEC 61158-5-21:2019)
Aplikacijski nivo procesnih vodil (FAL) uporabniškim programom omogoča dostop do komunikacijskega okolja procesnih vodil. Glede na to je mogoče aplikacijski nivo 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 protokol tipa 21. 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 mednarodni standard na abstrakten način določa zunanje vidno opravilo, ki ga zagotavlja aplikacijski nivo procesnih vodil v zvezi s/z: a) abstraktnim modelom za določanje aplikacijskih virov (objektov), ki jih uporabniki lahko spreminjajo prek opravila aplikacijskega nivoja procesnih vodil; b) primitivnimi dejanji in dogodki opravila; c) parametri, povezanimi z vsakim primitivnim dejanjem in dogodkom, kot tudi obliko, ki jo prevzamejo; d) medsebojno povezavo med temi dejanji in dogodki ter njihovimi veljavnimi zaporedji. Namen tega dokumenta je opredeliti opravila, ki se zagotavljajo za: a) uporabnika aplikacijskega nivoja procesnih vodil na meji med uporabnikom in aplikacijskim nivojem referenčnega modela procesnih vodil; b) upravljanje sistemov na meji med aplikacijskim nivojem in upravljanje sistemov referenčnega modela procesnih vodil. Ta dokument opisuje strukturo in opravila aplikacijskega nivoja procesnih vodil IEC v skladu z osnovnim referenčnim modelom OSI (ISO/IEC 7498) ter strukturo aplikacijskega nivoja OSI (ISO/IEC 9545). Opravila in protokole aplikacijskega nivoja procesnih vodil zagotavljajo aplikacijski osebki (AE) aplikacijskega nivoja procesnih vodil v aplikacijskih procesih. Aplikacijski osebek aplikacijskega nivoja procesnih vodil sestavljata sklop objektno usmerjenih aplikacijskih opravilnih elementov (ASE) in osebek za upravljanje nivojev (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 aplikacijskega nivoja procesnih vodil spada aplikacijski opravilni element za upravljanje, ki zagotavlja skupen sklop opravil za upravljanje primerkov razredov aplikacijskega nivoja procesnih vodil. Čeprav ta opravila z vidika aplikacij določajo način izdajanja ter dostavljanja zahtev in odzivov, ne zajemajo specifikacije v zvezi s tem, kako naj se nanje odzovejo aplikacije, ki te zahteve in odzive oddajajo. To pomeni, da ta opravila opredeljujejo samo zahteve in odzive, ki jih lahko aplikacije pošiljajo ali prejemajo, in ne funkcije samih aplikacij. Tako se uporabnikom aplikacijskega nivoja 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 aplikacijskega nivoja procesnih vodil za nadzorovanje nekaterih vidikov njegovega delovanja.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN IEC 61158-5-21:2019
01-november-2019
Nadomešča:
SIST EN 61158-5-21:2012
Industrijska komunikacijska omrežja - Specifikacije za procesna vodila - 5-21. del:
Definicija opravil na aplikacijski ravni - Elementi tipa 21 (IEC 61158-5-21:2019)
Industrial communication networks - Fieldbus specifications - Part 5-21: Application layer
service definition - Type 21 elements (IEC 61158-5-21:2019)
Industrielle Kommunikationsnetze - Feldbusse - Teil 5-21: Dienstfestlegungen des
Application Layer (Anwendungsschicht) - Typ 21-Elemente (IEC 61158-5-21:2019)
Réseaux de communication industriels- Spécifications des bus de terrain - Partie 5-21 :
Définition des services de la couche application - Éléments de type 21 (IEC 61158-5-
21:2019)
Ta slovenski standard je istoveten z: EN IEC 61158-5-21:2019
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
SIST EN IEC 61158-5-21:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN IEC 61158-5-21:2019
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SIST EN IEC 61158-5-21:2019
EUROPEAN STANDARD EN IEC 61158-5-21
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2019
ICS 25.040.40; 35.100.70; 35.110 Supersedes EN 61158-5-21:2012
English Version
Industrial communication networks - Fieldbus specifications -
Part 5-21: Application layer service definition - Type 21 elements
(IEC 61158-5-21:2019)
Réseaux de communication industriels- Spécifications des Industrielle Kommunikationsnetze - Feldbusse - Teil 5-21:
bus de terrain - Partie 5-21 : Définition des services de la Dienstfestlegungen des Application Layer
couche application - Éléments de type 21 (Anwendungsschicht) - Typ 21-Elemente
(IEC 61158-5-21:2019) (IEC 61158-5-21:2019)
This European Standard was approved by CENELEC on 2019-05-15. 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 61158-5-21:2019 E
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SIST EN IEC 61158-5-21:2019
EN IEC 61158-5-21:2019 (E)
European foreword
The text of document 65C/947/FDIS, future edition 2 of IEC 61158-5-21, 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
EN IEC 61158-5-21:2019.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2020-02-15
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2022-05-15
document have to be withdrawn
This document supersedes EN 61158-5-21:2012.
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 61158-5-21:2019 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 61158-2 NOTE Harmonized as EN 61158-2
2
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EN IEC 61158-5-21:2019 (E)
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
ISO/IEC/IEEE 2011 Information technology - Microprocessor - -
60559 Systems - Floating-Point arithmetic
IEC 61158-3-21 2019 Industrial communication networks - - -
Fieldbus specifications - Part 3-21: Data-
link layer service definition - Type 21
elements
IEC 61158-4-21 2019 Industrial communication networks - EN IEC 61158-4-21 2019
Fieldbus specifications - Part 4-21: Data-
link layer protocol specification - Type 21
elements
IEC 61158-6-21 2019 Industrial communication networks - EN 61158-6-21 2019
Fieldbus specifications - Part 6-21:
Application layer protocol specification -
Type 21 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 series 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
3
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SIST EN IEC 61158-5-21:2019
IEC 61158-5-21
®
Edition 2.0 2019-04
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 5-21: Application layer service definition – Type 21 elements
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.040.40; 35.100.70; 35.110 ISBN 978-2-8322-6752-3
Warning! Make sure that you obtained this publication from an authorized distributor.
® Registered trademark of the International Electrotechnical Commission
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SIST EN IEC 61158-5-21:2019
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CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
1.1 Overview . 8
1.2 Specifications . 9
1.3 Conformance . 9
2 Normative references . 9
3 Terms, definitions, symbols, abbreviations, and conventions . 10
3.1 Terms and definitions from other ISO/IEC standards . 10
3.1.1 ISO/IEC 7498-1 terms. 10
3.1.2 ISO/IEC 8822 terms . 10
3.1.3 ISO/IEC 8824-1 terms. 10
3.1.4 ISO/IEC 9545 terms . 11
3.2 Fieldbus data link layer terms . 11
3.3 Fieldbus application layer specific definitions . 11
3.4 Abbreviations and symbols . 17
3.5 Conventions . 17
3.5.1 Overview . 17
3.5.2 General conventions . 18
3.5.3 Conventions for class definitions . 18
3.5.4 Conventions for service definitions . 19
4 Concepts . 20
4.1 Common concepts . 20
4.1.1 Overview . 20
4.1.2 Architectural relationships . 21
4.1.3 Fieldbus application layer structure . 23
4.1.4 Fieldbus application layer naming and addressing . 34
4.1.5 Architecture summary . 35
4.1.6 FAL service procedures . 36
4.1.7 Common FAL attributes . 37
4.1.8 Common FAL service parameters . 37
4.1.9 APDU size . 38
4.2 Type specific concepts . 38
4.2.1 Node, AP, and object dictionary . 40
4.2.2 APO ASEs . 41
5 Data type ASE . 41
5.1 General . 41
5.1.1 Overview . 41
5.1.2 Basic type overview . 42
5.1.3 Fixed-length type overview . 42
5.1.4 Constructed type overview . 43
5.1.5 Specification of user-defined data types . 43
5.1.6 Transfer of user data . 43
5.2 Formal definition of data type objects . 44
5.2.1 Data type class . 44
5.3 FAL defined data types . 45
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5.3.1 Fixed-length types . 45
5.3.2 String types . 48
5.4 Data type ASE service specification . 49
6 Communication model specification . 49
6.1 ASEs . 49
6.1.1 Application process ASE . 49
6.1.2 Service data object ASE . 55
6.1.3 Process data object ASE . 65
6.1.4 Application relationship ASE . 68
6.2 ARs . 75
6.2.1 Point-to-point user-triggered confirmed client/server AREP (PTC-AR) . 75
6.2.2 Multipoint network-scheduled unconfirmed publisher-subscriber AREP
(MSU-AR) . 76
6.2.3 Multipoint user-triggered unconfirmed publisher-subscriber AREP
(MTU-AR) . 78
6.3 Summary of FAL classes . 79
6.4 Permitted FAL services by AREP role . 79
Bibliography . 80
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 . 30
Figure 8 – FAL management of objects . 31
Figure 9 – ASE service conveyance . 32
Figure 10 – Defined and established AREPs . 34
Figure 11 – FAL architectural components . 36
Figure 12 – Interaction between FAL and DLL . 39
Figure 13 – Publisher-subscriber communication model . 39
Figure 14 – Client-server communication model . 40
Figure 15 – Object model . 40
Figure 16 – ASEs of a Type 21 application . 41
Figure 17 – Data type class hierarchy example . 42
Figure 18 – The AR ASE conveys APDUs between APs . 68
Table 1 – Types of timeliness . 27
Table 2 – Overall structure of the OD . 40
Table 3 – Identify service . 52
Table 4 – Status service . 54
Table 5 – Access rights for object . 56
Table 6 – Read service . 57
Table 7 – Write service . 59
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Table 8 – Write and Read service . 61
Table 9 – Write and Read Multiple service . 63
Table 10 – TB-transfer . 67
Table 11 – COS-transfer . 67
Table 12 – Conveyance of service primitives by AREP role . 69
Table 13 – Valid combinations of AREP roles involved in an AR . 69
Table 14 – AR-unconfirmed send . 73
Table 15 – AR-confirmed send . 74
Table 16 – FAL class summary . 79
Table 17 – Services by AREP role . 79
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IEC 61158-5-21:2019 © IEC 2019 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 5-21: Application layer service definition –
Type 21 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 and IEC 61784-2.
International Standard IEC 61158-5-21 has been prepared by subcommittee 65C: Industrial
networks, of IEC technical committee 65: Industrial process measurement, control and
automation.
This second edition cancels and replaces the first edition published in 2010. This edition
constitutes a technical revision.
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This edition includes the following significant technical changes with respect to the previous
edition:
• added Write and Read service;
• miscellaneous editorial corrections.
The text of this International Standard is based on the following documents:
FDIS Report on voting
65C/947/FDIS 65C/950/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This publication has been drafted in accordance with ISO/IEC Directives, Part 2.
A list of all parts of the IEC 61158 series, published 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 publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be:
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
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IEC 61158-5-21:2019 © IEC 2019 – 7 –
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 may
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.
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INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 5-21: Application layer service definition –
Type 21 elements
1 Scope
1.1 Overview
The Fieldbus Application Layer (FAL) provides user programs with a means to access the
fieldbus communication environment. In this respect, the FAL can be considered a window
between corresponding application programs.
This part of IEC 61158 provides the common elements for basic time-critical and non-time-
critical messaging communications between application programs in an automation
environment as well as material specific to the Type 21 protocol. 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 defines, in an abstract way, the externally visible service provided
by the FAL in terms of:
a) an abstract model for defining application resources (objects) capable of being
manipulated by users via the FAL service;
b) the primitive actions and events of the service;
c) the parameters associated with each primitive action and event, and the form that they
take;
d) the interrelationship between these actions and events, and their valid sequences.
The purpose of this document is to define the services provided to:
a) the FAL-user at the boundary between the user and the application layer of the fieldbus
Reference Model;
b) systems management at the boundary between the application layer and systems
management of the fieldbus Reference Model.
This document describes the structure and services of the IEC FAL, in conformance with the
OSI Basic Reference Model (ISO/IEC 7498) and the OSI Application layer Structure
(ISO/IEC 9545).
FAL services and protocols are provided by FAL application entities (AEs) contained in 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 management of the instances of FAL classes.
Although these services specify how requests and responses are issued and delivered from
the perspective of applications, they do not include a specification of what the requesting and
responding applications are to do with them. That is, these services only define what requests
and responses applications can send or receive, not the functions of the applications
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SIST EN IEC 61158-5-21:2019
IEC 61158-5-21:2019 © IEC 2019 – 9 –
themselves. This permits greater flexibi
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