IEC 61158-1:2019
(Main)Industrial communication networks - Fieldbus specifications - Part 1: Overview and guidance for the IEC 61158 and IEC 61784 series
Industrial communication networks - Fieldbus specifications - Part 1: Overview and guidance for the IEC 61158 and IEC 61784 series
IEC 61158-1:2019 specifies the generic concept of fieldbuses. This document presents an overview and guidance for the IEC 61158 series explaining the structure and content of the IEC 61158 series, relating the structure of the IEC 61158 series to the ISO/IEC 7498-1 OSI Basic Reference Model and showing how to use parts of the IEC 61158 series in combination with the IEC 61784 series. It also provides explanations of some aspects of the IEC 61158 series that are common to the type specific parts of the IEC 61158 5 including the application layer service description concepts and the generic fieldbus data types. This second edition cancels and replaces the first edition published in 2014. This edition constitutes a technical revision.
This edition includes the following significant changes with respect to the previous edition:
• updates of the references to and information about the IEC 61158 series, IEC 61784 1, IEC 61784 3, IEC 61784-5 series and IEC 61918 throughout the document;
• new Type 25 and the related profile family CPF 20;
• new Type 26 and the related profile family CPF 21.
Réseaux de communication industriels - Spécifications des bus de terrain - Partie 1 : Vue d’ensemble et recommandations pour les séries IEC 61158 et IEC 61784
l’IEC 61158-1:2019 précise le concept générique de bus de terrain. Le présent document donne également une vue d’ensemble et des recommandations relatives à la série EC 61158 en:
• expliquant la structure et le contenu de la série IEC 61158;
• associant la structure de la série IEC 61158 à l’ISO/IEC 7498-1 Modèle de référence de base OSI;
• présentant la structure logique de la série IEC 61784;
• présentant la manière d’utiliser les parties de la série IEC 61158 en combinaison avec la série IEC 61784;
• donnant des explications relatives à certains aspects de la série IEC 61158 communs aux parties spécifiques au type de l’IEC 61158 5, y compris les concepts de description de la couche d’application de service et les types de données de bus de terrain génériques
Cette deuxième édition annule et remplace la première édition publiée en 2014. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l’édition précédente:
• mises à jour des références et des informations relatives à la série IEC 61158, à l’IEC 61784 1, à l’IEC 61784 3, à la série IEC 61784-5 et à l’IEC 61918 tout au long du document;
• nouveau Type 25 et la famille de profils CPF 20 associée;
• nouveau Type 26 et la famille de profils CPF 21 associée;
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IEC 61158-1 ®
Edition 2.0 2019-04
INTERNATIONAL
STANDARD
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Industrial communication networks – Fieldbus specifications –
Part 1: Overview and guidance for the IEC 61158 and IEC 61784 series
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IEC 61158-1 ®
Edition 2.0 2019-04
INTERNATIONAL
STANDARD
colour
inside
Industrial communication networks – Fieldbus specifications –
Part 1: Overview and guidance for the IEC 61158 and IEC 61784 series
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.040.40; 33.040.40; 35.100.05 ISBN 978-2-8322-6723-3
– 2 – IEC 61158-1:2019 © IEC 2019
CONTENTS
FOREWORD . 6
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 8
3.1 Terms and definitions . 8
3.2 Abbreviations . 9
4 Guidelines for implementers and users . 9
4.1 Background and purpose . 9
4.2 Supported options . 10
4.3 Benefits from using a common and formal style . 10
5 Concept of the IEC 61158 series . 11
6 Mapping onto the OSI Basic Reference Model . 13
6.1 Overview. 13
6.2 Physical layer service and protocol . 14
6.3 Data-link layer service . 14
6.4 Data-link layer protocol . 15
6.5 Application layer service . 15
6.6 Application layer protocol . 16
7 Structure of IEC 61158 and IEC 61784 series . 17
7.1 The IEC 61158 physical layer . 17
7.2 The IEC 61158 data-link layer . 17
7.3 The IEC 61158 application layer . 18
7.4 IEC 61784-1 and IEC 61784-2 fieldbus profiles . 18
7.5 IEC 61784-3 functional safety communication profiles. 22
7.5.1 General . 22
7.5.2 General concepts and technology-specific profiles . 22
7.5.3 Assessment Guideline . 24
7.6 IEC 61784-5 installation profiles . 24
7.7 Communication profiles for wireless communication networks . 26
8 Brief summary of the characteristics of service and protocol for each fieldbus type . 27
8.1 Summary of the physical layer service and protocol characteristics . 27
8.1.1 Type 1: media . 27
8.1.2 Type 2: Coaxial wire and optical media . 27
8.1.3 Type 3: Twisted-pair wire and optical media . 27
8.1.4 Type 4: Wire medium . 28
8.1.5 Type 5: Wire and optical media . 28
8.1.6 Type 6: Void . 28
8.1.7 Type 7: Wire and optical media . 28
8.1.8 Type 8: Twisted-pair wire and optical media . 28
8.1.9 Type 9: Wire and optical media . 28
8.1.10 Type 10: Wire, optical media and wireless . 28
8.1.11 Type 11: Wire and optical media . 28
8.1.12 Type 12: Wire and optical media . 28
8.1.13 Type 13: Wire and optical media . 28
8.1.14 Type 14: Wire and optical media . 28
8.1.15 Type 15: Wire and optical media . 29
8.1.16 Type 16: Optical media . 29
8.1.17 Type 17: Wire and optical media . 29
8.1.18 Type 18: Media . 29
8.1.19 Type 19: Wire and optical media . 29
8.1.20 Type 20 . 29
8.1.21 Type 21: Wire and optical media . 29
8.1.22 Type 22: Wire and optical media . 29
8.1.23 Type 23: Wire and optical media . 29
8.1.24 Type 24: Twisted-pair wire media . 29
8.1.25 Type 25: . 29
8.1.26 Type 26: Wire and optical media . 29
8.2 Summary of data-link layer service characteristics . 30
8.3 Summary of data-link layer protocol characteristics . 31
8.4 Summary of application layer service characteristics. 33
8.5 Summary of application layer protocol characteristics . 34
9 Application layer service description concepts . 37
9.1 Overview. 37
9.2 Architectural relationships . 37
9.2.1 Relationship to the application layer of the OSI Basic Reference Model . 37
9.2.2 Relationships to other fieldbus entities. 38
9.3 Fieldbus application layer structure . 39
9.3.1 Overview . 39
9.3.2 Fundamental concepts . 40
9.3.3 Fieldbus application processes . 40
9.3.4 Application process objects . 44
9.3.5 Application entities . 46
9.3.6 Fieldbus application service elements . 46
9.3.7 Application relationships . 50
9.4 Fieldbus application layer naming and addressing . 52
9.4.1 General . 52
9.4.2 Identifying objects accessed through the FAL . 52
9.4.3 Addressing APs accessed through the FAL. 53
9.5 Architecture summary . 53
9.6 Notional FAL service procedures . 54
9.6.1 Notional FAL confirmed service procedures . 54
9.6.2 Notional FAL unconfirmed service procedures . 54
9.7 Common FAL attributes . 55
9.8 Common FAL service parameters . 55
9.9 APDU size . 56
10 Data type ASE . 56
10.1 Overview. 56
10.1.1 General . 56
10.1.2 Overview of basic types . 57
10.1.3 Overview of fixed-length types . 58
10.1.4 Overview of constructed types . 58
10.1.5 Specification of user-defined data types . 58
10.1.6 Transfer of user data . 58
10.2 Formal definition of data type objects . 59
10.2.1 Data type class . 59
– 4 – IEC 61158-1:2019 © IEC 2019
11 Fieldbus system requirements . 60
11.1 General . 60
11.2 Industrial control network . 61
11.3 Communication between industrial control networks and other networks . 61
11.4 Quality of service features of an industrial control network . 61
11.4.1 General . 61
11.4.2 Control data transfer mechanisms . 62
11.5 Special requirements for wireless networks . 63
Annex A (informative) Trade name declarations . 64
Annex B (informative) Media selection for fieldbus systems . 67
B.1 General . 67
B.2 Cabled media . 67
B.3 Wireless media . 67
B.4 Media needing special consideration . 67
B.5 Performance characteristics of open and public networks . 67
B.5.1 Public network types . 67
B.5.2 Performance characteristics of public networks . 68
Bibliography . 69
Figure 1 – Example of a fieldbus system . 11
Figure 2 – Concept of DL/AL to separate service and protocol parts . 12
Figure 3 – Basic fieldbus reference model . 13
Figure 4 – General model of physical layer . 14
Figure 5 – Relationship of the Data-link layer to other fieldbus layers and to users of
the fieldbus data-link service. 15
Figure 6 – Relationship of the fieldbus Application layer to other fieldbus layers and to
users of the fieldbus application service . 16
Figure 7 – Structure of communication profile families . 19
Figure 8 – Example of a CPF structure . 20
Figure 9 – Document structure of IEC 61918 and the CPF specific part of IEC 61784-5 . 26
Figure 10 – Relationship to the OSI Basic Reference Model . 38
Figure 11 – Architectural positioning of the fieldbus application layer . 38
Figure 12 – Client/server interactions . 41
Figure 13 – Pull model interactions . 42
Figure 14 – Push model interactions . 43
Figure 15 – APOs services conveyed by the FAL . 44
Figure 16 – Application entity structure . 46
Figure 17 – Example FAL ASEs . 48
Figure 18 – FAL management of objects . 48
Figure 19 – ASE service conveyance . 49
Figure 20 – Defined and established AREPs . 52
Figure 21 – FAL architectural components . 53
Figure 22 – Data-type class hierarchy example . 57
Table 1 – OSI and IEC 61158 layers . 13
Table 2 – CPF, CP, and type relations . 21
Table 3 – Types of timeliness defined for publisher/subscriber interactions . 43
Table A.1 – Trade names of CPFs and CPs . 64
– 6 – IEC 61158-1:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 1: Overview and guidance for the IEC 61158 and IEC 61784 series
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
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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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 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 layer
protocol type to be used with other layer protocols of the same type, or in other type
combinations explicitly authorized by their respective intellectual property right holders.
NOTE Combinations of protocol types are specified in IEC 61784-1 and IEC 61784-2.
International Standard IEC 61158 1 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 2014. This edition
constitutes a technical revision.
This edition includes the following significant changes with respect to the previous edition:
• updates of the references to and information about the IEC 61158 series, IEC 61784-1,
IEC 61784-3, IEC 61784-5 series and IEC 61918 throughout the document;
• new Type 25 and the related profile family CPF 20;
• new Type 26 and the related profile family CPF 21.
The text of this International Standard is based on the following documents:
FDIS Report on voting
65C/944/FDIS 65C/953/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 document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all the 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 document will remain unchanged until the
stability date indicated on the IEC website under "http://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.
A bilingual version of this publication may be issued at a later date.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 8 – IEC 61158-1:2019 © IEC 2019
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 1: Overview and guidance for the IEC 61158 and IEC 61784 series
1 Scope
This part of IEC 61158 specifies the generic concept of fieldbuses.
This document also presents an overview and guidance for the IEC 61158 series by:
• explaining the structure and content of the IEC 61158 series;
• relating the structure of the IEC 61158 series to the ISO/IEC 7498-1 OSI Basic Reference
Model;
• showing the logical structure of the IEC 61784 series;
• showing how to use parts of the IEC 61158 series in combination with the IEC 61784
series;
• providing explanations of some aspects of the IEC 61158 series that are common to the
type specific parts of the IEC 61158-5 including the application layer service description
concepts and the generic fieldbus data types.
2 Normative references
There are no normative references in this document.
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
communication system
arrangement of hardware, software and propagation media to allow the transfer of messages
from one application to another
3.1.2
fieldbus
communication system based on serial data transfer as typically used in industrial automation
and process control applications
3.1.3
fieldbus system
system using a fieldbus with connected devices
3.1.4
message
ordered series of octets intended to convey information
3.1.5
network
all of the media, connectors, repeaters, routers, gateways and associated node
communication elements by which a given set of communicating devices are interconnected
3.2 Abbreviations
For the purposes of this document, the following abbreviations, based partially on the
concepts developed in ISO/IEC 7498-1, apply:
AE application entity
AL application layer (N = 7)
APDU application layer protocol data unit
APO application process object
AR application relationship
AREP application relationship endpoint
ASE application service element
CP communication profile
CPF communication profile family
DL- data-link layer (as a prefix)
DLL data-link layer (N = 2)
FAL fieldbus application layer
FSCP functional safety communication profile
IETF Internet Engineering Task Force
IO input output
IP Internet protocol (see RFC 791)
kbit/s thousand bit per second
Mbit/s million bit per second
LME layer management entity
(n)-layer layer n of the OSI basic reference model
OSI open systems interconnection
Ph- physical layer (as a prefix)
PhL physical layer (N = 1)
SIL safety integrity level
4 Guidelines for implementers and users
4.1 Background and purpose
Communication in global markets requires a global understanding of a specification (standard
or not). ISO/OSI related specifications provide a common basis for understanding and
acceptance between international experts (manufacturers and end-users).
– 10 – IEC 61158-1:2019 © IEC 2019
Examples are
• ISO/IEC 7498-1 for general layering and structuring;
• ISO/IEC 9545 for general application layer modeling;
• ISO/IEC 8886 for data-link layer modeling.
The IEC 61158 series specifies a number of different fieldbus types in each of its parts
(IEC 61158-2 and the type specific parts of IEC 61158-3-tt, IEC 61158-4-tt, IEC 61158-5-tt
and IEC 61158-6-tt). As a result of the editorial harmonization work done by IEC, each PhL,
DLL and AL specification within IEC 61158 is shown in a homogeneous way. The description
of each layer offers, as far as possible, common views, concepts, definitions, and descriptive
methods.
NOTE The list of IEC 61158 parts is abbreviated as IEC 61158-3-tt, IEC 61158-4-tt, IEC 61158-5-tt, or
IEC 61158-6-tt, where tt represents one or more type numbers.
This common approach has been adopted to assist users and implementers in understanding
the several specifications. It is also intended to assist in comparing available products and
their communications-related features.
4.2 Supported options
Most of the fieldbus types specified in the IEC 61158 series include a range of selectable and
configurable options within their detailed specifications. In general, only certain restricted
combinations of options will interwork or interoperate correctly.
The recommended combinations of options are collected in IEC 61784-1 and IEC 61784-2.
IEC 61784-1 and IEC 61784-2 provide users and implementers with details of supported
fieldbus specifications based on selected options that are intended to work together
consistently and correctly. In most cases, available product demonstrations and working plant
experience support these profiles.
Annex A of IEC 61784-1 and Annex A of IEC 61784-2 help select the needed fieldbus by
showing the key features of each of the profiled fieldbus protocol families.
As a result, the route map recommended to select a fieldbus is:
• Clause 5 to Clause 8 of this part of IEC 61158;
• IEC 61784-1, Annex A: Communication concepts;
• IEC 61784-2, Annex A: Performance indicator calculation;
• IEC 61784-1 and IEC 61784-2, Communication profile family;
• the parts of IEC 61158 as referenced in IEC 61784-1 and IEC 61784-2 for the selected
communication profile of interest.
4.3 Benefits from using a common and formal style
The benefits gained from using a common and formal style to specify the communication
system are:
• the common look and feel of a specification saves effort during evaluation;
• a common structure helps to identify and to specify common parts and contents;
• the common approach represents a first step to ensure long-term quality and stability;
• the missing parts and items of any specification are more readily identified by comparison
with the other specifications, leading to a simplified review and evaluation procedure;
• a common basis facilitates the development of test and certification procedures;
• the modular concepts support future enhancements, extensions and adaptation of new
technologies.
5 Concept of the IEC 61158 series
Conceptually, a fieldbus is an industrial digital communication network for integration of
industrial control and instrumentation devices into a system. Examples of such devices are
transducers, sensors, actuators and controllers.
The IEC 61158 series specifies a number of fieldbus protocol types. Each protocol type is
designed to permit multiple measurement and control devices to communicate. Devices
communicate directly only with other devices of the same protocol type. The basic
requirements of industrial communication networks for measurement and control are given in
Clause 11.
Devices which use the same lower-layer protocols in a compatible fashion but differ in their
higher-layer protocols may be able to share a lower-layer medium.
In all cases, a particular data-link layer protocol type may be used without restriction when
coupled with physical layer and application layer protocols of the same type or with other
combinations as specified in IEC 61784-1 and IEC 61784-2. Use of the various protocol types
in other combinations may require permission from their respective copyright holders.
The protocol types in IEC 61158 have been engineered to support information processing,
monitoring and control systems for any industrial sector and related domains. An example
application for high-integrity low-level communication between sensors, actuators and local
controllers in a process plant, together with the interconnection of programmable controllers,
is shown in Figure 1.
Figure 1 – Example of a fieldbus system
A number of fieldbus types are specified in the IEC 61158 series using the following concepts
for decomposition.
a) First concept: The complex communication task is divided into different layers based on
an adaptation of ISO/IEC 7498-1, the ISO/OSI Basic Reference Model, thereby facilitating
well-structured functions and interfaces (see Clause 6). This has the following benefits:
– 12 – IEC 61158-1:2019 © IEC 2019
– decomposition of complex tasks;
– modular structure to adapt different technologies.
b) Second concept: Each fieldbus type is composed of one or more layer specifications.
Most types include a number of services and protocol options that require an appropriate
selection to support a working system. Compatible selections of options and services
within one of the IEC 61158 fieldbus types are specified as standardized communication
profiles in IEC 61784-1 and IEC 61784-2. Most of these profiles are supported by
consortia or trade associations which are identified in the profile specification.
c) Third concept: The physical, data-link and application layers are described in
complementary ways, in terms of the offered services and the protocol which provides
those services.
Figure 2 illustrates the differences between service and protocol viewpoints of the data-link
and application layers. The protocol parts show the layer implementer’s oriented view and the
service parts show the layer user’s oriented view.
Figure 2 – Concept of DL/AL to separate service and protocol parts
The application layer structure is as follows:
– the "what“ is described by application layer service elements (ASE) in the type specific
parts of IEC 61158-5; and
– the "how“ is described by application layer relationships (AR) in the type specific parts of
IEC 61158-6.
The data-link layer structure is as follows:
– the "what“ is described by data-link layer services and models in the type specific parts of
IEC 61158-3; and
– the "how“ is described by data-link layer protocol machines and medium access principles
in the type specific parts of IEC 61158-4.
The physical layer is structured similarly, but, because its services are readily described, they
are described in IEC 61158-2 together with the definitions of the physical protocols:
– the "what“ is described by physical layer services and models, and
– the "how“ is described by physical layer electrical and mechanical specifications.
6 Mapping onto the OSI Basic Reference Model
6.1 Overview
IEC 61158 protocol types are described using the principles, methodology and model of
ISO/IEC 7498-1. The OSI model provides a layered approach to communications standards,
whereby the layers can be developed and modified independently. IEC 61158 specifies
functionality from top to bottom of a full OSI stack and, potentially, some functions for the
users of the stack. Functions of the intermediate OSI layers, layers 3 through 6, may be
consolidated into either the IEC 61158 data-link layer or the IEC 61158 application layer, or
may be realized by a separate layer. Likewise, some features common to users of the fieldbus
application layer may be provided by the IEC 61158 application layer to simplify user
operation.
Table 1 shows the OSI layers, their functions, and the equivalent layers in the IEC 61158
basic fieldbus reference model (Figure 3).
Table 1 – OSI and IEC 61158 layers
OSI layer Function IEC 61158 layer
Translates demands placed on the communications stack into a form Application
7 Application
understood by the lower layers and vice versa (IEC 61158-5-tt,
IEC 61158-6-tt)
6 Presentation Converts data to/from standardized network formats ↑
5 Session Creates and manages dialogue among lower layers
↑
4 Transport Provides transparent reliable data transfer (end-to-end transfer across a
↓ or ↑
network which may include multiple links)
3 Network Performs message routing ↓ or ↑
2 Data-link Controls access to the communication medium. Performs error Data-link
detection (point-to-point transfer on a link) (IEC 61158-3-tt,
IEC 61158-4-tt)
Encodes/decodes signals for transmission/reception in a form
1 Physical
Physical
appropriate to the communications medium. Specifies communication
(IEC 61158-2)
media characteristics
NOTE 1 -tt is a placeholder for the part numbers representing types.
NOTE 2 ↓ and ↑ indicate that the functionality of this layer, when present, is included in the fieldbus layer that is
nearest in the direction of the arrow. Thus it is possible that the network and transport functionality are included in
either the data-link or application layers, and it is possible that the session and presentation functionality are
included in the application layer but not in the data-link layer.
Figure 3 – Basic fieldbus reference model
– 14 – IEC 61158-1:2019 © IEC 2019
6.2 Physical layer service and protocol
IEC 61158-2 comprises physical layer specifications corresponding to many of the different
DL-Layer protocol types specified in the type specific parts of IEC 61158-4.
NOTE 1 The type numbers used are consistent throughout the IEC 61158 series.
NOTE 2 Not all types have a physical layer specification in IEC 61158-2. In that case the communication profile in
IEC 61784-1 or IEC 61784-2 provides appropriate references to other standards.
NOTE 3 For ease of reference, type numbers are given in clause names. This means that the specification given
therein applies to this type but does not exclude its use for other types.
NOTE 4 It is up to the user of IEC 61158 to select interoperating sets of provisions. Refer to IEC 61784-1 and
IEC 61784-2 for standardized communication profiles based on IEC 61158.
A general model of the physical layer is shown in Figure 4.
Figure 4 – General model of physical layer
NOTE 5 The protocol types use a subset of the structure elements.
NOTE 6 Since Type 8 uses a more complex DIS than the other types, it uses the term MIS to differentiate.
The common characteristics for all variants and types are as follows:
– digital data transmission; and
– either half-duplex communication (bi-directional but in only one direction at a time) or full-
duplex communication.
6.3 Data-link layer service
The data-link service is provided by the data-link protocol making use of the services
available from the physical layer. This and related parts of the IEC 61158 series defines the
data-link service characteristics that the immediately higher-level protocol may exploit. The
relationship between the international standards for fieldbus data-link service, fieldbus data-
link protocol, fieldbus application protocol and systems management is illustrated in Figure 5.
NOTE Systems management, as used in the IEC 61158 series, is a local mechanism for managing the layer
protocols.
Figure 5 – Relationship of the Data-link layer
to other fieldbus layers and to users of the fieldbus data-link service
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,
a data-link service defined in IEC 61158 is a conceptual architectural service, independent of
administrative and implementation divisions.
6.4 Data-link layer protocol
The data-link protocol provides the data-link service by making use of the services available
from the physical layer. The relationship between the International Standards for fieldbus
data-link service, fieldbus data-link protocol, fieldbus physical service and systems
management is illustrated in Figure 5.
NOTE 1 Systems management, as used in the IEC 61158 series, is a local mechanism for managing the layer
protocols.
NOTE 2 Not all types have a data-link layer specification. In that case the communication profile in IEC 61784-1
or IEC 61784-2 provides appropriate references to other standards.
The primary aim of the data-link protocol standards is to provide a set of rules for
communication expressed in terms of the procedures to be carried out by peer data-link
entities (DLEs) 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:
a) as a guide for implementers and designers;
b) for use in the testing and procurement of equipment;
c) as part of an agreement for the admittance of systems into the open systems environment;
d) as a refinement to the understanding of time-critical communications within OSI.
These data-link protocol standards are concerned, in particular, with the communication and
interworking of sensors, effectors and other automation devices, using these standards,
together with other standards positioned within the OSI or fieldbus reference models;
otherwise, incompatible systems may work together in any combination.
6.5 Application layer service
The application service is provided by the application protocol making use of the services
available from the data-link or other immediately lower layer. Each part of the IEC 61158-5
series defines the application service characteristics that any immediately higher-level
protocols may exploit. The relationship between the international standards for fieldbus
– 16 – IEC 61158-1:2019 © IEC 2019
application service, fieldbus application protocol and systems management is illustrated in
Figure 6.
NOTE Systems management, as used in the IEC 61158 series, is a local mechanism for managing the layer
protocols.
Figure 6 – Relationship of the fieldbus Application layer
to other fieldbus layers and to users of the fieldbus application service
6.6 Application layer prot
...
IEC 61158-1 ®
Edition 2.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Industrial communication networks – Fieldbus specifications –
Part 1: Overview and guidance for the IEC 61158 and IEC 61784 series
Réseaux de communication industriels – Spécifications des bus de terrain –
Partie 1: Vue d’ensemble et recommandations pour les séries IEC 61158 et
IEC 61784
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IEC 61158-1 ®
Edition 2.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Industrial communication networks – Fieldbus specifications –
Part 1: Overview and guidance for the IEC 61158 and IEC 61784 series
Réseaux de communication industriels – Spécifications des bus de terrain –
Partie 1: Vue d’ensemble et recommandations pour les séries IEC 61158 et
IEC 61784
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.040.40; 33.040.40; 35.100.05 ISBN 978-2-8322-7953-3
– 2 – IEC 61158-1:2019 © IEC 2019
CONTENTS
FOREWORD . 6
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 8
3.1 Terms and definitions . 8
3.2 Abbreviations . 9
4 Guidelines for implementers and users . 9
4.1 Background and purpose . 9
4.2 Supported options . 10
4.3 Benefits from using a common and formal style . 10
5 Concept of the IEC 61158 series . 11
6 Mapping onto the OSI Basic Reference Model . 13
6.1 Overview. 13
6.2 Physical layer service and protocol . 14
6.3 Data-link layer service . 14
6.4 Data-link layer protocol . 15
6.5 Application layer service . 16
6.6 Application layer protocol . 16
7 Structure of IEC 61158 and IEC 61784 series . 17
7.1 The IEC 61158 physical layer . 17
7.2 The IEC 61158 data-link layer . 17
7.3 The IEC 61158 application layer . 18
7.4 IEC 61784-1 and IEC 61784-2 fieldbus profiles . 18
7.5 IEC 61784-3 functional safety communication profiles. 23
7.5.1 General . 23
7.5.2 General concepts and technology-specific profiles . 23
7.5.3 Assessment Guideline . 25
7.6 IEC 61784-5 installation profiles . 25
7.7 Communication profiles for wireless communication networks . 27
8 Brief summary of the characteristics of service and protocol for each fieldbus type . 28
8.1 Summary of the physical layer service and protocol characteristics . 28
8.1.1 Type 1: media . 28
8.1.2 Type 2: Coaxial wire and optical media . 28
8.1.3 Type 3: Twisted-pair wire and optical media . 28
8.1.4 Type 4: Wire medium . 29
8.1.5 Type 5: Wire and optical media . 29
8.1.6 Type 6: Void . 29
8.1.7 Type 7: Wire and optical media . 29
8.1.8 Type 8: Twisted-pair wire and optical media . 29
8.1.9 Type 9: Wire and optical media . 29
8.1.10 Type 10: Wire, optical media and wireless . 29
8.1.11 Type 11: Wire and optical media . 29
8.1.12 Type 12: Wire and optical media . 29
8.1.13 Type 13: Wire and optical media . 29
8.1.14 Type 14: Wire and optical media . 29
8.1.15 Type 15: Wire and optical media . 30
8.1.16 Type 16: Optical media . 30
8.1.17 Type 17: Wire and optical media . 30
8.1.18 Type 18: Media . 30
8.1.19 Type 19: Wire and optical media . 30
8.1.20 Type 20 . 30
8.1.21 Type 21: Wire and optical media . 30
8.1.22 Type 22: Wire and optical media . 30
8.1.23 Type 23: Wire and optical media . 30
8.1.24 Type 24: Twisted-pair wire media . 30
8.1.25 Type 25: . 30
8.1.26 Type 26: Wire and optical media . 30
8.2 Summary of data-link layer service characteristics . 31
8.3 Summary of data-link layer protocol characteristics . 32
8.4 Summary of application layer service characteristics. 34
8.5 Summary of application layer protocol characteristics . 35
9 Application layer service description concepts . 38
9.1 Overview. 38
9.2 Architectural relationships . 38
9.2.1 Relationship to the application layer of the OSI Basic Reference Model . 38
9.2.2 Relationships to other fieldbus entities. 39
9.3 Fieldbus application layer structure . 40
9.3.1 Overview . 40
9.3.2 Fundamental concepts . 41
9.3.3 Fieldbus application processes . 41
9.3.4 Application process objects . 45
9.3.5 Application entities . 47
9.3.6 Fieldbus application service elements . 47
9.3.7 Application relationships . 51
9.4 Fieldbus application layer naming and addressing . 53
9.4.1 General . 53
9.4.2 Identifying objects accessed through the FAL . 53
9.4.3 Addressing APs accessed through the FAL. 54
9.5 Architecture summary . 54
9.6 Notional FAL service procedures . 55
9.6.1 Notional FAL confirmed service procedures . 55
9.6.2 Notional FAL unconfirmed service procedures . 55
9.7 Common FAL attributes . 56
9.8 Common FAL service parameters . 56
9.9 APDU size . 57
10 Data type ASE . 57
10.1 Overview. 57
10.1.1 General . 57
10.1.2 Overview of basic types . 58
10.1.3 Overview of fixed-length types . 59
10.1.4 Overview of constructed types . 59
10.1.5 Specification of user-defined data types . 59
10.1.6 Transfer of user data . 59
10.2 Formal definition of data type objects . 60
10.2.1 Data type class . 60
– 4 – IEC 61158-1:2019 © IEC 2019
11 Fieldbus system requirements . 61
11.1 General . 61
11.2 Industrial control network . 62
11.3 Communication between industrial control networks and other networks . 62
11.4 Quality of service features of an industrial control network . 62
11.4.1 General . 62
11.4.2 Control data transfer mechanisms . 63
11.5 Special requirements for wireless networks . 64
Annex A (informative) Trade name declarations . 65
Annex B (informative) Media selection for fieldbus systems . 68
B.1 General . 68
B.2 Cabled media . 68
B.3 Wireless media . 68
B.4 Media needing special consideration . 68
B.5 Performance characteristics of open and public networks . 68
B.5.1 Public network types . 68
B.5.2 Performance characteristics of public networks . 69
Bibliography . 70
Figure 1 – Example of a fieldbus system . 11
Figure 2 – Concept of DL/AL to separate service and protocol parts . 12
Figure 3 – Basic fieldbus reference model . 13
Figure 4 – General model of physical layer . 14
Figure 5 – Relationship of the Data-link layer to other fieldbus layers and to users of
the fieldbus data-link service. 15
Figure 6 – Relationship of the fieldbus Application layer to other fieldbus layers and to
users of the fieldbus application service . 16
Figure 7 – Structure of communication profile families . 20
Figure 8 – Example of a CPF structure . 21
Figure 9 – Document structure of IEC 61918 and the CPF specific part of IEC 61784-5 . 27
Figure 10 – Relationship to the OSI Basic Reference Model . 39
Figure 11 – Architectural positioning of the fieldbus application layer . 39
Figure 12 – Client/server interactions . 42
Figure 13 – Pull model interactions . 43
Figure 14 – Push model interactions . 44
Figure 15 – APOs services conveyed by the FAL . 45
Figure 16 – Application entity structure . 47
Figure 17 – Example FAL ASEs . 49
Figure 18 – FAL management of objects . 49
Figure 19 – ASE service conveyance . 50
Figure 20 – Defined and established AREPs . 53
Figure 21 – FAL architectural components . 54
Figure 22 – Data-type class hierarchy example . 58
Table 1 – OSI and IEC 61158 layers . 13
Table 2 – CPF, CP, and type relations . 22
Table 3 – Types of timeliness defined for publisher/subscriber interactions . 44
Table A.1 – Trade names of CPFs and CPs . 65
– 6 – IEC 61158-1:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 1: Overview and guidance for the IEC 61158 and IEC 61784 series
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 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 layer
protocol type to be used with other layer protocols of the same type, or in other type
combinations explicitly authorized by their respective intellectual property right holders.
NOTE Combinations of protocol types are specified in IEC 61784-1 and IEC 61784-2.
International Standard IEC 61158 1 has been prepared by subcommittee 65C: Industrial
networks, of IEC technical committee 65: Industrial-process measurement, control and
automation.
This bilingual version (2020-03) corresponds to the monolingual English version, published in
2019-04.
This second edition cancels and replaces the first edition published in 2014. This edition
constitutes a technical revision.
This edition includes the following significant changes with respect to the previous edition:
• updates of the references to and information about the IEC 61158 series, IEC 61784-1,
IEC 61784-3, IEC 61784-5 series and IEC 61918 throughout the document;
• new Type 25 and the related profile family CPF 20;
• new Type 26 and the related profile family CPF 21.
The text of this International Standard is based on the following documents:
FDIS Report on voting
65C/944/FDIS 65C/953/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.
The French version of this standard has not been voted upon.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all the 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 document will remain unchanged until the
stability date indicated on the IEC website under "http://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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 8 – IEC 61158-1:2019 © IEC 2019
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 1: Overview and guidance for the IEC 61158 and IEC 61784 series
1 Scope
This part of IEC 61158 specifies the generic concept of fieldbuses.
This document also presents an overview and guidance for the IEC 61158 series by:
• explaining the structure and content of the IEC 61158 series;
• relating the structure of the IEC 61158 series to the ISO/IEC 7498-1 OSI Basic Reference
Model;
• showing the logical structure of the IEC 61784 series;
• showing how to use parts of the IEC 61158 series in combination with the IEC 61784
series;
• providing explanations of some aspects of the IEC 61158 series that are common to the
type specific parts of the IEC 61158-5 including the application layer service description
concepts and the generic fieldbus data types.
2 Normative references
There are no normative references in this document.
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
communication system
arrangement of hardware, software and propagation media to allow the transfer of messages
from one application to another
3.1.2
fieldbus
communication system based on serial data transfer as typically used in industrial automation
and process control applications
3.1.3
fieldbus system
system using a fieldbus with connected devices
3.1.4
message
ordered series of octets intended to convey information
3.1.5
network
all of the media, connectors, repeaters, routers, gateways and associated node
communication elements by which a given set of communicating devices are interconnected
3.2 Abbreviations
For the purposes of this document, the following abbreviations, based partially on the
concepts developed in ISO/IEC 7498-1, apply:
AE application entity
AL application layer (N = 7)
APDU application layer protocol data unit
APO application process object
AR application relationship
AREP application relationship endpoint
ASE application service element
CP communication profile
CPF communication profile family
DL- data-link layer (as a prefix)
DLL data-link layer (N = 2)
FAL fieldbus application layer
FSCP functional safety communication profile
IETF Internet Engineering Task Force
IO input output
IP Internet protocol (see RFC 791)
kbit/s thousand bit per second
Mbit/s million bit per second
LME layer management entity
(n)-layer layer n of the OSI basic reference model
OSI open systems interconnection
Ph- physical layer (as a prefix)
PhL physical layer (N = 1)
SIL safety integrity level
4 Guidelines for implementers and users
4.1 Background and purpose
Communication in global markets requires a global understanding of a specification (standard
or not). ISO/OSI related specifications provide a common basis for understanding and
acceptance between international experts (manufacturers and end-users).
– 10 – IEC 61158-1:2019 © IEC 2019
Examples are
• ISO/IEC 7498-1 for general layering and structuring;
• ISO/IEC 9545 for general application layer modeling;
• ISO/IEC 8886 for data-link layer modeling.
The IEC 61158 series specifies a number of different fieldbus types in each of its parts
(IEC 61158-2 and the type specific parts of IEC 61158-3-tt, IEC 61158-4-tt, IEC 61158-5-tt
and IEC 61158-6-tt). As a result of the editorial harmonization work done by IEC, each PhL,
DLL and AL specification within IEC 61158 is shown in a homogeneous way. The description
of each layer offers, as far as possible, common views, concepts, definitions, and descriptive
methods.
NOTE The list of IEC 61158 parts is abbreviated as IEC 61158-3-tt, IEC 61158-4-tt, IEC 61158-5-tt, or
IEC 61158-6-tt, where tt represents one or more type numbers.
This common approach has been adopted to assist users and implementers in understanding
the several specifications. It is also intended to assist in comparing available products and
their communications-related features.
4.2 Supported options
Most of the fieldbus types specified in the IEC 61158 series include a range of selectable and
configurable options within their detailed specifications. In general, only certain restricted
combinations of options will interwork or interoperate correctly.
The recommended combinations of options are collected in IEC 61784-1 and IEC 61784-2.
IEC 61784-1 and IEC 61784-2 provide users and implementers with details of supported
fieldbus specifications based on selected options that are intended to work together
consistently and correctly. In most cases, available product demonstrations and working plant
experience support these profiles.
Annex A of IEC 61784-1 and Annex A of IEC 61784-2 help select the needed fieldbus by
showing the key features of each of the profiled fieldbus protocol families.
As a result, the route map recommended to select a fieldbus is:
• Clause 5 to Clause 8 of this part of IEC 61158;
• IEC 61784-1, Annex A: Communication concepts;
• IEC 61784-2, Annex A: Performance indicator calculation;
• IEC 61784-1 and IEC 61784-2, Communication profile family;
• the parts of IEC 61158 as referenced in IEC 61784-1 and IEC 61784-2 for the selected
communication profile of interest.
4.3 Benefits from using a common and formal style
The benefits gained from using a common and formal style to specify the communication
system are:
• the common look and feel of a specification saves effort during evaluation;
• a common structure helps to identify and to specify common parts and contents;
• the common approach represents a first step to ensure long-term quality and stability;
• the missing parts and items of any specification are more readily identified by comparison
with the other specifications, leading to a simplified review and evaluation procedure;
• a common basis facilitates the development of test and certification procedures;
• the modular concepts support future enhancements, extensions and adaptation of new
technologies.
5 Concept of the IEC 61158 series
Conceptually, a fieldbus is an industrial digital communication network for integration of
industrial control and instrumentation devices into a system. Examples of such devices are
transducers, sensors, actuators and controllers.
The IEC 61158 series specifies a number of fieldbus protocol types. Each protocol type is
designed to permit multiple measurement and control devices to communicate. Devices
communicate directly only with other devices of the same protocol type. The basic
requirements of industrial communication networks for measurement and control are given in
Clause 11.
Devices which use the same lower-layer protocols in a compatible fashion but differ in their
higher-layer protocols may be able to share a lower-layer medium.
In all cases, a particular data-link layer protocol type may be used without restriction when
coupled with physical layer and application layer protocols of the same type or with other
combinations as specified in IEC 61784-1 and IEC 61784-2. Use of the various protocol types
in other combinations may require permission from their respective copyright holders.
The protocol types in IEC 61158 have been engineered to support information processing,
monitoring and control systems for any industrial sector and related domains. An example
application for high-integrity low-level communication between sensors, actuators and local
controllers in a process plant, together with the interconnection of programmable controllers,
is shown in Figure 1.
Figure 1 – Example of a fieldbus system
A number of fieldbus types are specified in the IEC 61158 series using the following concepts
for decomposition.
a) First concept: The complex communication task is divided into different layers based on
an adaptation of ISO/IEC 7498-1, the ISO/OSI Basic Reference Model, thereby facilitating
well-structured functions and interfaces (see Clause 6). This has the following benefits:
– 12 – IEC 61158-1:2019 © IEC 2019
– decomposition of complex tasks;
– modular structure to adapt different technologies.
b) Second concept: Each fieldbus type is composed of one or more layer specifications.
Most types include a number of services and protocol options that require an appropriate
selection to support a working system. Compatible selections of options and services
within one of the IEC 61158 fieldbus types are specified as standardized communication
profiles in IEC 61784-1 and IEC 61784-2. Most of these profiles are supported by
consortia or trade associations which are identified in the profile specification.
c) Third concept: The physical, data-link and application layers are described in
complementary ways, in terms of the offered services and the protocol which provides
those services.
Figure 2 illustrates the differences between service and protocol viewpoints of the data-link
and application layers. The protocol parts show the layer implementer’s oriented view and the
service parts show the layer user’s oriented view.
Figure 2 – Concept of DL/AL to separate service and protocol parts
The application layer structure is as follows:
– the "what“ is described by application layer service elements (ASE) in the type specific
parts of IEC 61158-5; and
– the "how“ is described by application layer relationships (AR) in the type specific parts of
IEC 61158-6.
The data-link layer structure is as follows:
– the "what“ is described by data-link layer services and models in the type specific parts of
IEC 61158-3; and
– the "how“ is described by data-link layer protocol machines and medium access principles
in the type specific parts of IEC 61158-4.
The physical layer is structured similarly, but, because its services are readily described, they
are described in IEC 61158-2 together with the definitions of the physical protocols:
– the "what“ is described by physical layer services and models, and
– the "how“ is described by physical layer electrical and mechanical specifications.
6 Mapping onto the OSI Basic Reference Model
6.1 Overview
IEC 61158 protocol types are described using the principles, methodology and model of
ISO/IEC 7498-1. The OSI model provides a layered approach to communications standards,
whereby the layers can be developed and modified independently. IEC 61158 specifies
functionality from top to bottom of a full OSI stack and, potentially, some functions for the
users of the stack. Functions of the intermediate OSI layers, layers 3 through 6, may be
consolidated into either the IEC 61158 data-link layer or the IEC 61158 application layer, or
may be realized by a separate layer. Likewise, some features common to users of the fieldbus
application layer may be provided by the IEC 61158 application layer to simplify user
operation.
Table 1 shows the OSI layers, their functions, and the equivalent layers in the IEC 61158
basic fieldbus reference model (Figure 3).
Table 1 – OSI and IEC 61158 layers
OSI layer Function IEC 61158 layer
Translates demands placed on the communications stack into a form Application
7 Application
understood by the lower layers and vice versa (IEC 61158-5-tt,
IEC 61158-6-tt)
6 Presentation Converts data to/from standardized network formats ↑
5 Session Creates and manages dialogue among lower layers
↑
4 Transport Provides transparent reliable data transfer (end-to-end transfer across a
↓ or ↑
network which may include multiple links)
3 Network Performs message routing ↓ or ↑
2 Data-link Controls access to the communication medium. Performs error Data-link
detection (point-to-point transfer on a link) (IEC 61158-3-tt,
IEC 61158-4-tt)
Encodes/decodes signals for transmission/reception in a form
1 Physical
Physical
appropriate to the communications medium. Specifies communication
(IEC 61158-2)
media characteristics
NOTE 1 -tt is a placeholder for the part numbers representing types.
NOTE 2 ↓ and ↑ indicate that the functionality of this layer, when present, is included in the fieldbus layer that is
nearest in the direction of the arrow. Thus it is possible that the network and transport functionality are included in
either the data-link or application layers, and it is possible that the session and presentation functionality are
included in the application layer but not in the data-link layer.
Figure 3 – Basic fieldbus reference model
– 14 – IEC 61158-1:2019 © IEC 2019
6.2 Physical layer service and protocol
IEC 61158-2 comprises physical layer specifications corresponding to many of the different
DL-Layer protocol types specified in the type specific parts of IEC 61158-4.
NOTE 1 The type numbers used are consistent throughout the IEC 61158 series.
NOTE 2 Not all types have a physical layer specification in IEC 61158-2. In that case the communication profile in
IEC 61784-1 or IEC 61784-2 provides appropriate references to other standards.
NOTE 3 For ease of reference, type numbers are given in clause names. This means that the specification given
therein applies to this type but does not exclude its use for other types.
NOTE 4 It is up to the user of IEC 61158 to select interoperating sets of provisions. Refer to IEC 61784-1 and
IEC 61784-2 for standardized communication profiles based on IEC 61158.
A general model of the physical layer is shown in Figure 4.
Figure 4 – General model of physical layer
NOTE 5 The protocol types use a subset of the structure elements.
NOTE 6 Since Type 8 uses a more complex DIS than the other types, it uses the term MIS to differentiate.
The common characteristics for all variants and types are as follows:
– digital data transmission; and
– either half-duplex communication (bi-directional but in only one direction at a time) or full-
duplex communication.
6.3 Data-link layer service
The data-link service is provided by the data-link protocol making use of the services
available from the physical layer. This and related parts of the IEC 61158 series defines the
data-link service characteristics that the immediately higher-level protocol may exploit. The
relationship between the international standards for fieldbus data-link service, fieldbus data-
link protocol, fieldbus application protocol and systems management is illustrated in Figure 5.
NOTE Systems management, as used in the IEC 61158 series, is a local mechanism for managing the layer
protocols.
Figure 5 – Relationship of the Data-link layer
to other fieldbus layers and to users of the fieldbus data-link service
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,
a data-link service defined in IEC 61158 is a conce
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