EN 61158-6-7:2008

Industrial communication networks - Fieldbus specifications - Part 6-7: Application layer protocol specification - Type 7 elements

It 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 standard 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 7 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. It includes the following significant changes from the previous edition deletion of the former Type 6 fieldbus for lack of market relevance; addition of new types of fieldbuses; partition of part 6 of the third edition into multiple parts numbered.

Industrielle Kommunikationsnetze - Feldbusse - Teil 6-7: Protokollspezifikation des Application Layer (Anwendungsschicht) - Typ 7-Elemente

Réseaux de communication industriels - Spécifications des bus de terrain - Partie 6-7: Spécification des protocoles des couches d'application - Eléments de type 7

La CEI 61158-6-7:2007 décrit la couche d'application de bus de terrain (FAL, "Fieldbus Application Layer") qui fournit aux programmes utilisateur un moyen d'accès à l'environnement de communication des bus de terrain. À cet égard, la FAL peut être considérée comme une "fenêtre entre les programmes d'application correspondants." Elle spécifie le protocole de la couche application de bus de terrain de Type 7, conformément au modèle de référence de base OSI (ISO/CEI 7498) et à la structure de la couche application OSI (ISO/CEI 9545). Cette première édition et ses parties d'accompagnement de la série CEI 61158-6 annulent et remplacent la CEI 61158-6:2003. Elle inclut les modifications suivantes: - suppression de l'ancien bus de terrain de Type 6 du fait d'un manque de pertinence pour le marché; - addition de nouveaux types de bus de terrain; - répartition de la partie 6 de la troisième édition en plusieurs parties numérotées -6 2, -6 3,... La présente version bilingue (2013-09) correspond à la version anglaise monolingue publiée en 2007-12.

Industrijska komunikacijska omrežja - Specifikacije za procesno vodilo - 6-7. del: Specifikacija protokola na aplikacijskem nivoju - Elementi tipa 7 (IEC 61158-6-7:2007)

General Information

• Status: Published
• Publication Date: 30-Mar-2008
• Withdrawal Date: 31-Jan-2011
• ICS: 25.040.40 - Industrial process measurement and control
• ICS: 35.100.70 - Application layer
• Technical Committee: CLC/TC 65X - Industrial-process measurement, control and automation
• Drafting Committee: IEC/SC 65C - IEC_SC_65C
• Parallel Committee: IEC/SC 65C - IEC_SC_65C
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 31-Mar-2008
• Completion Date: 31-Mar-2008
• Mandate: M/490 - Standardisation mandate to the European Standardisation Organisations (ESOs) to support European Smart Grid deployment
• Ref Project: SIST EN 61158-6-7:2008 - Industrial communication networks - Fieldbus specifications - Part 6-7: Application layer protocol specification - Type 7 elements

Relations

• Replaces: EN 61158-6:2004 - Digital data communication for measurement and control - Fieldbus for use in industrial control systems - Part 6: Application layer protocol specification
• Effective Date: 29-Jan-2023

Overview

EN 61158-6-7:2008 (IEC 61158-6-7:2007) is a European/CENELEC adoption of the IEC fieldbus application-layer protocol specification for Type 7 fieldbus elements. It specifies the Fieldbus Application Layer (FAL)-the “window between corresponding application programs”-providing common elements for both time‑critical and non‑time‑critical messaging in automation systems. The standard targets industrial communication networks and defines how user programs access the fieldbus communication environment in safety‑ and reliability‑sensitive contexts.

Key topics and technical requirements

The standard covers a broad set of technical topics required to implement the Type 7 application layer:

• FAL services and primitives for application-to-application messaging (SUB‑MMS projection and MCS services).
• Abstract syntax and transfer syntaxes (including compact encoding and ASN.1-related constructs) for data types and PDUs.
• PDU formats and encoding rules (CompactValue, variable/type/list descriptions, bitstring and floating-point encodings).
• Protocol machine structure and multiple protocol state machines:
  • AP‑context state machine, Association Relationship Protocol Machine (ARPM)
  • DLL mapping protocol machine (DMPM)
  • SUB‑MMS FAL Service Protocol Machine (FSPM)
  • Transfer, segmentation/reassembly, numbering, retry and anticipation mechanisms
• Association management: establishment, termination, revocation and associated state transitions.
• Conformance classes and protocol options to guide implementers on mandatory vs optional features.
• Notes on time‑critical messaging semantics and required deterministic behaviour to mitigate risks to equipment, plant and human life.
• Intellectual property and interoperability guidance (use in combination with physical/data-link layers per EN 61784).

Practical applications and users

EN 61158-6-7:2008 is intended for practitioners implementing or deploying fieldbus systems in industrial automation, including:

• Fieldbus protocol designers and firmware developers implementing the Type 7 application layer.
• Device manufacturers producing PLCs, I/O modules, drives and safety devices requiring standard FAL behaviour.
• System integrators and control engineers designing deterministic communication for process and factory automation.
• Certification and test laboratories validating conformance, interoperability and timing behaviour.
• Standards bodies and technical committees harmonizing protocol stacks (linking with data-link and physical layers).

This standard is particularly relevant where time‑critical messaging, deterministic transfer, and robust association/state management are required.

Related standards

• IEC/EN 61158 series (Parts 3‑7, 4‑7, 5‑7) for data‑link and application-layer service definitions
• EN 61784 (fieldbus profiles / type combinations)
• ISO/IEC 7498-1 (OSI reference model) and ASN.1/BER encoding references

Keywords: EN 61158-6-7:2008, Type 7, fieldbus, application layer, Fieldbus Application Layer (FAL), industrial communication networks, time-critical messaging, automation.

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2008
1DGRPHãþD
SIST EN 61158-6:2004
Industrijska komunikacijska omrežja - Specifikacije za procesno vodilo - 6-7. del:
Specifikacija protokola na aplikacijskem nivoju - Elementi tipa 7 (IEC 61158-6-
7:2007)
Industrial communication networks - Fieldbus specifications - Part 6-7: Application layer
protocol specification - Type 7 elements
Industrielle Kommunikationsnetze - Feldbusse - Teil 6-7: Protokollspezifikation des
Application Layer (Anwendungsschicht) - Typ 7-Elemente
Réseaux de communication industriels - Spécifications des bus de terrain - Partie 6-7:
Spécification des services des couches d'application - Eléments de type 7
Ta slovenski standard je istoveten z: EN 61158-6-7:2008
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 61158-6-7
NORME EUROPÉENNE
March 2008
EUROPÄISCHE NORM
ICS 35.100.70; 25.040.40 Partially supersedes EN 61158-6:2004

English version
Industrial communication networks -
Fieldbus specifications -
Part 6-7: Application layer protocol specification -
Type 7 elements
(IEC 61158-6-7:2007)
Réseaux de communication industriels -  Industrielle Kommunikationsnetze -
Spécifications des bus de terrain - Feldbusse -
Partie 6-7: Spécification des services Teil 6-7: Protokollspezifikation
des couches d'application - des Application Layer
Eléments de type 7 (Anwendungsschicht) -
(CEI 61158-6-7:2007) Typ 7-Elemente
(IEC 61158-6-7:2007)
This European Standard was approved by CENELEC on 2008-02-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2008 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61158-6-7:2008 E
Foreword
The text of document 65C/476/FDIS, future edition 1 of IEC 61158-6-7, 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 was approved by CENELEC as EN 61158-6-7 on 2008-02-01.
This and the other parts of the EN 61158-6 series supersede EN 61158-6:2004.
With respect to EN 61158-6:2004 the following changes were made:
– deletion of Type 6 fieldbus for lack of market relevance;
– addition of new fieldbus types;
– partition into multiple parts numbered 6-2, 6-3, …6-20.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2008-11-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2011-02-01
NOTE  Use of some of the associated protocol types is restricted by their intellectual-property-right holders. In all cases, the
commitment to limited release of intellectual-property-rights made by the holders of those rights permits a particular data-link layer
protocol type to be used with physical layer and application layer protocols in type combinations as specified explicitly in the
EN 61784 series. Use of the various protocol types in other combinations may require permission from their respective
intellectual-property-right holders.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61158-6-7:2007 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 61784-1 NOTE  Harmonized as EN 61784-1:2008 (not modified).
__________
- 3 - EN 61158-6-7:2008
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application 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  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year
1) 2)
IEC 60559 - Binary floating-point arithmetic for HD 592 S1 1991
microprocessor systems
1) 2)
IEC 61158-3-7 - Industrial communication networks - EN 61158-3-7 2008
Fieldbus specifications -
Part 3-7: Data-link layer service definition -
Type 7 elements
1) 2)
IEC 61158-4-7 - Industrial communication networks - EN 61158-4-7 2008
Fieldbus specifications -
Part 4-7: Data-link layer protocol
specification - Type 7 elements

1) 2)
IEC 61158-5-7 - Industrial communication networks - EN 61158-5-7 2008
Fieldbus specifications -
Part 5-7: Application layer service definition -
Type 7 elements
1) 2)
ISO/IEC 7498-1 - Information technology - Open Systems EN ISO/IEC 7498-1 1995
Interconnection - Basic Reference Model:
The Basic Model
1)
ISO/IEC 8824-2 - Information technology - Abstract Syntax - -
Notation One (ASN.1): Information object
specification
1)
ISO/IEC 8825-1 - Information technology - ASN.1 encoding - -
rules: Specification of Basic Encoding Rules
(BER), Canonical Encoding Rules (CER) and
Distinguished Encoding Rules (DER)

1) 2)
ISO/IEC 9506-2 - Industrial automation systems - EN 29506-2 1990
Manufacturing message specification -
Part 2: Protocol specification

1)
ISO/IEC 9545 - Information technology - Open Systems - -
Interconnection - Application Layer structure

1)
Undated reference.
2)
Valid edition at date of issue.

IEC 61158-6-7
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 6-7: Application layer protocol specification – Type 7 elements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XG
ICS 35.100.70; 25.040.40 ISBN 2-8318-9484-0

– 2 – 61158-6-7 © IEC:2007(E)
CONTENTS
FOREWORD.6
INTRODUCTION.8
1 Scope.9
1.1 General .9
1.2 Specifications.9
1.3 Conformance.9
2 Normative references .10
3 Terms, definitions, symbols, abbreviations and conventions .10
3.1 Terms and definitions from other ISO/IEC standards .10
3.2 Terms and definitions from IEC 61158-5-7.11
3.3 Additional terms and definitions.12
3.4 Abbreviations and symbols.16
3.5 Conventions .16
3.6 Conventions used in state machines .16
4 Abstract syntax of data type .17
4.1 Data abstract syntax specification .17
4.2 FAL PDU abstract syntax .21
5 Transfer syntaxes.22
5.1 Compact encoding.22
5.2 Data type encoding .23
6 Structure of protocol machines .82
7 AP-context state machine.83
8 Sub-MMS FAL service protocol machine (FSPM).83
8.1 General .83
8.2 Projection of the SUB-MMS PDUs on the MCS services .83
8.3 Projection of the SUB-MMS abort service on the MCS services .83
8.4 Construction of a SUB-MMS-PDU from a service primitive .84
8.5 Extraction of a valid service primitive from a SUB-MMS-PDU .84
8.6 Negotiation of an abstract syntax and a transfer syntax commonly called
presentation-context.84
8.7 Identification of the SUB-MMS core abstract syntax .86
8.8 Identification of the application context name .87
8.9 Identification of the ASE of the core abstract syntax and the transfer syntax .87
9 Association relationship protocol machine (ARPM ) .87
10 DLL mapping protocol machine (DMPM).88
10.1 MPS ARPM and DMPM .88
10.2 MCS ARPM and DMPM .99
11 Protocol options .135
11.1 Conformances classes .135
Bibliography.155

Figure 1 – Example of an evaluation net .17
Figure 2 – Encoding of a CompactValue .22
Figure 3 – Organisation of the bits and octets within a PDU.24

61158-6-7 © IEC:2007(E) – 3 –
Figure 4 – Encoding of a Bitstring .27
Figure 5 – Encoding of a Floating point value .28
Figure 6 – Encoding of a structure .29
Figure 7 – Encoding of a Boolean array .30
Figure 8 – Representation of a MCS PDU .36
Figure 9 – Relationships among Protocol Machines and Adjacent Layers .82
Figure 10 – A_Readloc service evaluation net .88
Figure 11 – A_Writeloc service evaluation net.89
Figure 12 – A_Update service evaluation net .90
Figure 13 – A_Readfar service evaluation net.91
Figure 14 – A_Writefar service evaluation net .93
Figure 15 – A_Sent service evaluation net .94
Figure 16 – A_Received service evaluation net.94
Figure 17 – Association establishment: Requester element state machine . 101
Figure 18 – Association establishment: Responder element state machine . 102
Figure 19 – Association termination: Requester element state machine . 104
Figure 20 – Association termination: Responder element state machine . 106
Figure 21 – Association revocation: Requester element state machine . 107
Figure 22 – Association revocation: Acceptor element state machine. 108
Figure 23 – Interactions between state machine in an associated mode data transfer . 110
Figure 24 – Transfer service: Requester element state machine . 114
Figure 25 – Transfer service: Acceptor element state machine . 115
Figure 26 – Unacknowledged transfer: Requester element state machine . 116
Figure 27 – Unacknowledged transfer: Acceptor element state machine . 116
Figure 28 – Acknowledged transfer: Requester element state machine . 118
Figure 29 – Acknowledged transfer: Acceptor element state machine . 119
Figure 30 – Numbering mechanism state machine .120
Figure 31 – Retry machanism state machine.122
Figure 32 – Anticipation mechanism state machine.125
Figure 33 – Segmentation mechanism state machine.127
Figure 34 – Reassembly mechanism state machine . 129
Figure 35 – Interaction of state machine in a non associated data transfer . 131
Figure 36 – Unacknowledged transfer: Requester element state machine . 132
Figure 37 – Unacknowledged transfer: Acceptor element state machine . 132
Figure 38 – Acknowledged transfer: Requester element state machine . 133
Figure 39 – Acknowledged transfer: Acceptor element state machine . 134

Table 1 – Example of encoding of a SEQUENCE .19
Table 2 – Example of encoding of a SEQUENCE OF .19
Table 3 – Example of encoding of a CHOICE.20
Table 4 – Example of encoding of an object identifier .21
Table 5 – Example of encoding of a PDU.22
Table 6 – MPS PDU types .25

– 4 – 61158-6-7 © IEC:2007(E)
Table 7 – Fields of a CompactValuePDU .25
Table 8 – Fields of a VariableDescriptionPDU.32
Table 9 – Fields of an AccessDescriptionPDU .33
Table 10 – Fields of a TypeDescriptionPDU.34
Table 11 – Fields of a ListDescriptionPDU .35
Table 12 – Coding of the different MCS PDU types.37
Table 13 – Coding of the variable part of the PDU .37
Table 14 – Structure of association establishment request.38
Table 15 – Structure of an associated establishment response .42
Table 16 – Structure of an association termination request .44
Table 17 – Structure of an association termination response .44
Table 18 – Structure of an association revocation request .45
Table 19 – Structure of an associated transfer request .46
Table 20 – Structure of an associated transfer acknowledgement .46
Table 21 – Structure of a non-associated transfer request .47
Table 22 – Structure of a non-associated transfer acknowledgement .48
Table 23 – Definitions of object classes .50
Table 24 – Definition of Sub-MMS Services .51
Table 25 – Structure of the antiduplication list.123
Table 26 – Structure of the reassembly list .128
Table 27 – PV_R/W parameter values .136
Table 28 – PV_IND parameter values .136
Table 29 – PV_LIS parameter values.136
Table 30 – Constraints on PV_LIS parameter .137
Table 31 – PV_AT parameter values.137
Table 32 – PV_RE parameter values .137
Table 33 – PV_UT parameter values.137
Table 34 – Constraints on PV_RE parameter .137
Table 35 – PH_R_A parameter values .138
Table 36 – PH_R_S parameter values .138
Table 37 – PH_R_P parameter values .138
Table 38 – PH_P_A parameter values .139
Table 39 – PH_P_S parameter values .139
Table 40 – PH_P_P parameter values .139
Table 41 – PH_COH parameter values .139
Table 42 – PH_FIA parameter values.140
Table 43 – PH_SPF parameter values .140
Table 44 – PH_SPM parameter values.140
Table 45 – PH_ACC parameter values.141
Table 46 – PH_RES parameter values .141
Table 47 – PH_AK parameter values .141
Table 48 – PH_RA parameter values .141
Table 49 – PH_SR parameter values .141

61158-6-7 © IEC:2007(E) – 5 –
Table 50 – PH_CF parameter values .142
Table 51 – Constraints on PH_RA parameter.142
Table 52 – Constraints on PH_SR parameter.142
Table 53 – PT_OCT parameter values .142
Table 54 – PT_BIN parameter values.143
Table 55 – PT_VIS parameter values.143
Table 56 – PT_BOO parameter values.143
Table 57 – PT_BCD parameter values .143
Table 58 – PT_BTM parameter values .144
Table 59 – PT_INT parameter values.144
Table 60 – PT_UNS parameter values .144
Table 61 – PT_FPT parameter values.144
Table 62 – PT_GTM parameter values.145
Table 63 – PT_TAB parameter values.145
Table 64 – PT_STR parameter values .145
Table 65 – Constraints on PT_TAB parameter .146
Table 66 – Constraints on PT_STR parameter .146
Table 67 – Conformance classes for environment management. 149
Table 68 – Conformance classes for VMD management .150
Table 69 – Conformance classes for PI managment.151
Table 70 – Conformance classes for domain management. 152
Table 71 – Conformance classes for variable/variable list management .153
Table 72 – Conformance classes for event management . 154

– 6 – 61158-6-7 © IEC:2007(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 6-7: Application layer protocol specification – Type 7 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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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.
NOTE  Use of some of the associated protocol types is restricted by their intellectual-property-right holders. In all
cases, the commitment to limited release of intellectual-property-rights made by the holders of those rights permits
a particular data-link layer protocol type to be used with physical layer and application layer protocols in Type
combinations as specified explicitly in the IEC 61784 series. Use of the various protocol types in other
combinations may require permission from their respective intellectual-property-right holders.
International Standard IEC 61158-6-7 has been prepared by subcommittee 65C: Industrial
networks, of IEC technical committee 65: Industrial-process measurement, control and
automation.
This first edition and its companion parts of the IEC 61158-6 subseries cancel and replace
IEC 61158-6:2003. This edition of this part constitutes an editorial revision.
This edition of IEC 61158-6 includes the following significant changes from the previous
edition:
a) deletion of the former Type 6 fieldbus for lack of market relevance;
b) addition of new types of fieldbuses;
c) partition of part 6 of the third edition into multiple parts numbered -6-2, -6-3, …

61158-6-7 © IEC:2007(E) – 7 –
The text of this standard is based on the following documents:
FDIS Report on voting
65C/476/FDIS 65C/487/RVD
Full information on the voting for the approval of this 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.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result 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.
NOTE  The revision of this standard will be synchronized with the other parts of the IEC 61158 series.
The 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.

– 8 – 61158-6-7 © IEC:2007(E)
INTRODUCTION
This part of IEC 61158 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/TR 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 standard
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 implementors 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 standard is concerned, in particular, with the communication and interworking of sensors,
effectors and other automation devices. By using this standard together with other standards
positioned within the OSI or fieldbus reference models, otherwise incompatible systems may
work together in any combination.

61158-6-7 © IEC:2007(E) – 9 –
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 6-7: Application layer protocol specification – Type 7 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 standard 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 7 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 standard specifies interactions between remote applications and defines the externally
visible behavior provided by the Type 7 fieldbus application layer in terms of
a) the formal abstract syntax defining the application layer protocol data units conveyed
between communicating application entities;
b) the transfer syntax defining encoding rules that are applied to the application layer
protocol data units;
c) the application context state machine defining the application service behavior visible
between communicating application entities;
d) the application relationship state machines defining the communication behavior visible
between communicating application entities.
The purpose of this standard is to define the protocol provided to
• define the wire-representation of the service primitives defined in IEC 61158-5-7, and
• define the externally visible behavior associated with their transfer.
This standard specify the protocol of the Type 7 fieldbus application layer, in conformance
with the OSI Basic Reference Model (ISO/IEC 7498) and the OSI application layer structure
(ISO/IEC 9545).
1.2 Specifications
The principal objective of this standard is to specify the syntax and behavior of the application
layer protocol that conveys the application layer services defined in IEC 61158-5-7.
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 parts of the IEC 61158-6 series.
1.3 Conformance
This standard does not specify individual implementations or products, nor does it constrain
the implementations of application layer entities within industrial automation systems.

– 10 – 61158-6-7 © IEC:2007(E)
There is no conformance of equipment to the application layer service definition standard.
Instead, conformance is achieved through implementation of this application layer protocol
specification.
2 Normative references
The following referenced documents are indispensable for the application 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.
IEC 60559, Binary floating-point arithmetic for microprocessor systems
IEC 61158-3-7, Industrial communication networks – Fieldbus specifications – Part 3-7: Data-
link layer service definition – Type 7 elements
IEC 61158-4-7, Industrial communication networks – Fieldbus specifications – Part 4-7: Data-
link layer protocol specification – Type 7 elements
IEC 61158-5-7, Industrial communication networks – Fieldbus specifications – Part 5-7:
Application layer service definition – Type 7 elements
ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference
Model — Part 1: The Basic Model
ISO/IEC 8824, Information technology – Open Systems Interconnection – Specification of
Abstract Syntax Notation One (ASN.1)
ISO/IEC 8825, Information technology – ASN.1 encoding rules: Specification of Basic
Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules
(DER)
ISO/IEC 9506-2, Industrial automation systems – Manufacturing Message Specification – Part
2: Protocol specification
ISO/IEC 9545, Information technology – Open Systems Interconnection – Application Layer
structure
3 Terms, definitions, symbols, abbreviations and conventions
For the purposes of this document, the following definitions apply.
3.1 Terms and definitions from other ISO/IEC standards
3.1.1 Terms and definitions from ISO/IEC 7498-1
a) abstract syntax
b) application entity
c) application process
d) application protocol data unit
e) application service element
f) application entity invocation
g) application process invocation
h) application transaction
i) presentation context
j) real open system
k) transfer syntax
61158-6-7 © IEC:2007(E) – 11 –
3.1.2 Terms and definitions from ISO/IEC 9545
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
3.1.3 Terms and definitions from ISO/IEC 8824
a) object identifier
b) type
c) value
d) simple type
e) structured type
f) component type
g) tag
h) Boolean type
i) true
j) false
k) integer type
l) bitstring type
m) octetstring type
n) null type
o) sequence type
p) sequence of type
q) choice type
r) tagged type
s) any type
t) module
u) production
3.1.4 Terms and definitions from ISO/IEC 8825
a) encoding (of a data value)
b) data value
c) identifier octets (the singular form is used in this standard)
d) length octet(s) (both singular and plural forms are used in this standard)
e) contents octets
3.2 Terms and definitions from IEC 61158-5-7
a) application relationship
b) conveyance path
c) client
d) dedicated AR
e) dynamic AR
f) error class
g) error code
h) name
i) numeric identifier
j) peer
k) pre-defined AR endpoint
l) pre-established AR endpoint
m) publisher
n) subscriber
– 12 – 61158-6-7 © IEC:2007(E)
3.3 Additional terms and definitions
3.3.1
allocate
take a resource from a common area and assign that resource for the exclusive use of a
specific entity
3.3.2
application
function or data structure for which data is consumed or produced
3.3.3
application objects
multiple object classes that manage and provide a run time exchange of messages across the
network and within the network device
3.3.4
attribute
description of an externally visible characteristic or feature of an object
NOTE 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 may also affect the behaviour of an object.
Attributes are divided into class attributes and instance attributes.
3.3.5
behaviour
indication of how an object responds to particular events
3.3.6
called
service user or a service provider that receives an indication primitive or a request APDU
3.3.7
calling
service user or a service provider that initiates a request primitive or a request APDU
3.3.8
class
set of objects, all of which represent the same kind of system component
NOTE 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 behaviour, but usually contain different data in their attributes.
3.3.9
class attributes
attribute that is shared by all objects within the same class
3.3.10
class code
unique identifier assigned to each object class
3.3.11
class specific service
service defined by a particular object class to perform a required function which is not
performed by a common service
NOTE A class specific object is unique to the object class which defines it

61158-6-7 © IEC:2007(E) – 13 –
3.3.12
client
a) object which uses the services of another (server) object to perform a task
b) initiator of a message to which a server reacts
3.3.13
clock
device providing a measurement of the passage of time since a defined epoch
NOTE  There are two types of clocks in IEC 61588, boundary clocks and ordinary clocks.
3.3.14
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, Message Router object.
3.3.15
connection
logical binding between application objects that may be within the same or different devices
NOTE Connections may be either point-to-point or multipoint.
3.3.16
connection ID (CID)
identifier assigned to a transmission that is associated with a particular connection between
producers and consumers, providing a name for a specific piece of application information
3.3.17
connection point
buffer which is represented as a subinstance of an Assembly object
3.3.18
consume
act of receiving data from a producer
3.3.19
consumer
node or sink that is receiving data from a producer
3.3.20
consuming application
application that consumes data
3.3.21
cyclic
repetitive in a regular manner
3.3.22
device
physical hardware connected to the link
NOTE: A device may contain more than one node.
3.3.23
device profile
collection of device dependent information and functionality providing consistency between
similar devices of the same device type

– 14 – 61158-6-7 © IEC:2007(E)
3.3.24
end node
producing or consuming node
3.3.25
end point
one of the communicating entities involved in a connection
3.3.26
error
discrepancy between a computed, observed or measured value or condition and the specified
or theoretically correct value or condition
3.3.27
frame
denigrated synonym for DLPDU
3.3.28
instance
the actual physical occurrence of an object within a class, identifying one of many objects
within the same object class.
EXAMPLE California is an instance of the object class state.
NOTE The terms object, instance, and object instance are used to refer to a specific instance.
3.3.29
instance attribute
attribute that is unique to an object instance and not shared by the object class
3.3.30
instantiated
object that has been created in a device
3.3.31
interoperability
capability of User Layer entities to perform coordinated and cooperative operations using the
services of the FAL
3.3.32
little endian
Describes a model of memory organisation which stores the least significant octet at the
lowest address, or for transfer, which transfers the lowest order octet first
3.3.33
management information
network accessible information that supports the management of the Fieldbus environment
3.3.34
member
piece of an attribute that is structured as an element of an array
3.3.35
message router
object within a node that distributes messaging requests to appropriate application objects
3.3.36
multipoint connection
SIST EN 61158-6-7:
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