IEC 61158-6-28:2023

Industrial communication networks - Fieldbus specifications - Part 6-28: Application layer protocol specification - Type 28 elements

IEC 61158-6-28:2023 provides common elements for basic time-critical and non-time-critical messaging communications between application programs in an automation environment and material specific to Type 28 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 can cause failure of the applications requesting the actions, with attendant risk to equipment, plant and possibly human life.

Réseaux de communication industriels - Spécifications des bus de terrain - Partie 6-28: Spécification du protocole de la couche application - Éléments de type 28

L’IEC 61158-6-28:2023 donne les éléments communs visant à assurer les communications de messagerie de base prioritaires et non prioritaires entre les programmes d’application d’un environnement d’automatisation et d’un matériel spécifique au bus de terrain de type 28. Le terme "prioritaire" est utilisé pour indiquer la présence d’une fenêtre temporelle, dans laquelle il est exigé de réaliser une ou plusieurs actions spécifiées selon un niveau défini de certitude. La non-réalisation des actions spécifiées dans la fenêtre temporelle peut provoquer la défaillance des applications qui les demandent, avec les risques associés pour l’équipement, l’usine, voire les personnes.

General Information

• Status: Published
• Publication Date: 23-Mar-2023
• ICS: 25.040 - Industrial automation systems
• Technical Committee: SC 65C - Industrial networks
• Drafting Committee: WG 9 - TC 65/SC 65C/WG 9
• Current Stage: PPUB - Publication issued
• Start Date: 31-Mar-2023
• Completion Date: 24-Mar-2023

Standards Content (Sample)

IEC 61158-6-28
®

Edition 1.0 2023-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Industrial communication networks – Fieldbus specifications –
Part 6-28: Application layer protocol specification – Type 28 elements

Réseaux de communication industriels – Spécifications des bus de terrain –
Partie 6-28: Spécification du protocole de la couche application – Éléments de
type 28

IEC 61158-6-28:2023-03(en-fr)

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IEC 61158-6-28

®


Edition 1.0 2023-03




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE











Industrial communication networks – Fieldbus specifications –

Part 6-28: Application layer protocol specification – Type 28 elements



Réseaux de communication industriels – Spécifications des bus de terrain –

Partie 6-28: Spécification du protocole de la couche application – Éléments de

type 28















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 25.040 ISBN 978-2-8322-6621-2




Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – IEC 61158-6-28:2023 © IEC 2023
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
1.1 Overview. 7
1.2 Specifications . 7
1.3 Conformance . 8
2 Normative references . 8
3 Terms, definitions, symbols, abbreviated terms and conventions . 9
3.1 Terms and definitions from other ISO/IEC standards . 9
3.1.1 Terms and definitions from ISO/IEC 7498-1 . 9
3.1.2 Terms and definitions from ISO/IEC 9545 . 9
3.1.3 Terms and definitions from ISO/IEC 8824-1 . 9
3.1.4 Terms and definitions from ISO/IEC 8825-7 . 9
3.1.5 Terms and definitions from IEC 61158-5 . 10
3.2 Type 28 fieldbus application-layer specific definitions . 10
3.3 Abbreviations and symbols . 10
3.4 Conventions . 11
3.4.1 General concept . 11
3.4.2 Conventions for class definitions . 11
3.4.3 Abstract syntax conventions . 11
3.5 Conventions used in state machines . 11
3.5.1 State machine conventions for Type 28 . 11
4 APDU structure . 12
4.1 APDU header . 12
4.2 DTU APDU . 14
4.3 Time service notification APDU . 15
4.4 System management APDU . 16
5 State machine . 17
5.1 Publisher state machine . 17
5.2 Subscriber state machine . 19
5.3 Client state machine . 20
5.4 Server state machine . 21
5.5 ALCE state machine . 22
5.6 ALDE state machine . 22
5.7 ALME state machine . 23
Bibliography . 25

Figure 1 – APDU header structure . 12
Figure 2 – APDU structure of multiple DTUs . 14
Figure 3 – Transmission unit APDU structure . 14
Figure 4 – Time service notification APDU structure . 15
Figure 5 – System management data APDU structure . 17
Figure 6 – Diagram of state transition of publisher state machine . 18
Figure 7 – Diagram of state transition of subscriber state machine . 20
Figure 8 – Diagram of state transition of client state machine . 21

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IEC 61158-6-28:2023 © IEC 2023 – 3 –
Figure 9 – Diagram of transition state of server state machine . 21
Figure 10 – Diagram of transition state of ALCE state machine . 22
Figure 11 – Diagram of transition state of ALDE state machine . 23
Figure 12 – Diagram of state transition for ALME state machine . 24

Table 1 – State machine description elements . 11
Table 2 – AL service type flag encoding . 12
Table 3 – State transition table of publisher state machine . 18
Table 4 – State transition table of subscriber state machine . 19
Table 5 – State transition table of client state machine . 20
Table 6 – State transition table of server state machine . 21
Table 7 – State transition table of ALCE state machine . 22
Table 8 – State transition table of ALDE state machine . 23
Table 9 – State transition table of ALME state machine . 24

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –

Part 6-28: Application layer protocol specification –
Type 28 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
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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
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
Attention is drawn to the fact that the use of the associated protocol type is restricted by its
intellectual-property-right holders. In all cases, the commitment to limited release of intellectual-
property-rights made by the holders of those rights permits a layer protocol type to be used with
other layer protocols of the same type, or in other type combinations explicitly
authorized by its intellectual-property-right holders.
NOTE Combinations of protocol types are specified in the IEC 61784-1 series and the IEC 61784-2 series.
IEC 61158-6-28 has been prepared by subcommittee 65C: Industrial networks, of IEC technical
committee 65: Industrial-process measurement, control and automation. It is an International
Standard.

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IEC 61158-6-28:2023 © IEC 2023 – 5 –
The text of this International Standard is based on the following documents:
Draft Report on voting
65C/1206/FDIS 65C/1235/RVD

Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all 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 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.

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– 6 – IEC 61158-6-28:2023 © IEC 2023
INTRODUCTION
This document is one of a series produced to facilitate the interconnection of automation system
components. It is related to other standards in the set as defined by the "three-layer" fieldbus
reference model described in IEC 61158-1.
The application 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 document
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 implementers 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 document is concerned, in particular, with the communication and interworking of sensors,
effectors and other automation devices. By using this document together with other standards
positioned within the OSI or fieldbus reference models, otherwise incompatible systems can
work together in any combination.

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IEC 61158-6-28:2023 © IEC 2023 – 7 –
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –

Part 6-28: Application layer protocol specification –
Type 28 elements



1 Scope
1.1 Overview
The Fieldbus Application Layer (FAL) provides user programs with a means to access the
fieldbus communication environment. In this respect, the FAL can be considered as a window
between corresponding application programs.
This part of IEC 61158 provides common elements for basic time-critical and non-time-critical
messaging communications between application programs in an automation environment and
material specific to Type 28 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
can cause failure of the applications requesting the actions, with attendant risk to equipment,
plant and possibly human life.
This document defines in an abstract way the externally visible behavior provided by the
Type 28 of the fieldbus Application Layer in terms of:
• the abstract syntax defining the application layer protocol data units conveyed between
communicating application entities,
• the transfer syntax defining the application layer protocol data units conveyed between
communicating application entities,
• the application context state machine defining the application service behavior visible
between communicating application entities; and
• the application relationship state machines defining the communication behavior visible
between communicating application entities.
The purpose of this document is to define the protocol provided to:
• the wire-representation of the service primitives defined in IEC 61158-5-28, and
• the externally visible behavior associated with their transfer.
This document specifies the protocol of the Type 28 IEC 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 document is to specify the syntax and behavior of the application
layer protocol that conveys the application layer services defined in IEC 61158-5-28.
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 IEC 61158-6 series.

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1.3 Conformance
This document does not specify individual implementations or products, nor does it constrain
the implementations of application layer entities within industrial automation systems.
Conformance is achieved through implementation of this application layer protocol specification.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
NOTE All parts of the IEC 61158 series, as well as the IEC 61784-1 series and the IEC 61784-2 series are
maintained simultaneously. Cross-references to these documents within the text therefore refer to the editions as
dated in this list of normative references.
IEC 61158-1:2023, Industrial communication networks – Fieldbus specifications – Part 1:
Overview and guidance for the IEC 61158 and IEC 61784 series
IEC 61158-5-28:2023, Industrial communication networks – Fieldbus specifications – Part 5-28:
Application layer service definition – Type 28 elements
ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference
Model – Basic Reference Model: The Basic Model
ISO/IEC 7498-3, Information technology – Open Systems Interconnection – Basic Reference
Model: Naming and addressing
ISO/IEC 8824-1, Information technology – Abstract Syntax Notation One (ASN.1) – Partie 1:
Specification of basic notation
ISO/IEC 8825-7:2021, Information technology - ASN.1 encoding rules − Part 7: Specification of
Octet Encoding Rules (OER)
ISO/IEC 9545, Information technology – Open Systems Interconnection – Application Layer
structure
ISO/IEC/IEEE 8802-3:2021, Information technology – Telecommunications and information
exchange between systems – Local and metropolitan area networks – Specific requirements –
Part 3: Standard for Ethernet
IETF RFC 791, J. Postel, “Internet Protocol”, September 1981, available at https://www.rfc-
editor.org/info/rfc791 [viewed 2022-09-14]
IETF RFC 2460, S. Deering and R. Hinden, “Internet Protocol, Version 6 (IPv6) Specification”,
December 1998, available at https://www.rfc-editor.org/info/rfc2460 [viewed 2022-09-14]

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IEC 61158-6-28:2023 © IEC 2023 – 9 –
3 Terms, definitions, symbols, abbreviated terms and conventions
For the purposes of this document, the following terms, definitions, symbols, abbreviated terms
and conventions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1 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 transaction
g) presentation context
h) transfer syntax
3.1.2 Terms and definitions from ISO/IEC 9545
a) application-association
b) application-process-type
c) application-service-element
d) application control service element
3.1.3 Terms and definitions from ISO/IEC 8824-1
a) object identifier
b) type
c) value
d) simple type
e) structured type
f) integer type
g) octet string type
h) null type
i) tagged type
j) any type
k) module
l) production
3.1.4 Terms and definitions from ISO/IEC 8825-7
a) encoding (of a data value)
b) data value
c) identifier octets (the singular form is used in this document)
d) length octet(s) (both singular and plural forms are used in this document)
e) contents octets

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3.1.5 Terms and definitions from IEC 61158-5
a) cyclic
b) field device
c) clock synchronization
3.2 Type 28 fieldbus application-layer specific definitions
3.2.1
control device
device that controls all field devices for logical operations, timing, calculations, etc.
3.2.2
management node
device for allocating and managing Type 28 network physical communication resources
3.2.3
terminal node
device in Type 28 network that communicates based on allocated physical communication
resources
3.2.4
RT Data
data sensitive to time deterministic requirements
3.2.5
non-RT Data
data insensitive to time deterministic requirements
3.3 Abbreviations and symbols
AL Application layer
ALCE Application layer clock entity
ALDE Application layer data entity
ALME Application layer management entity
ALS Application layer service
AE Application entity
AP Application process
APDU Application protocol data unit
APO AP object
AR Application relationship
ASE Application service elements
C/S Client/Server
DTU Data transmission unit
DLSDU Data-link service data unit
DLPDU Data-link protocol data unit
MN Management node
PUD Protocol unit data
RT Real-Time
RTA Real-Time acyclic
RTC Real-Time cyclic
TCD Time command code

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IEC 61158-6-28:2023 © IEC 2023 – 11 –
TCV Time Consumption value
TID Time ID
TIV Time information value
nRT non-Real-Time
TN Terminal node
3.4 Conventions
3.4.1 General concept
The FAL is defined as a set of object-oriented ASEs. Each ASE is specified in a separate
subclause. Each ASE specification is composed of three parts: its class definitions, its services,
and its protocol specification. The first two are contained in IEC 61158-5-28. The protocol
specification for each of the ASEs is defined in this document.
The class definitions define the attributes of the classes supported by each ASE. The attributes
are accessible from instances of the class using the Management ASE services specified in
IEC 61158-5-28. The service specification defines the services that are provided by the ASE.
3.4.2 Conventions for class definitions
The data-link layer mapping definitions are described using templates. Each template consists
of a list of attributes for the class. The general form of the template is defined in IEC 61158-1.
3.4.3 Abstract syntax conventions
When the "optional Parameters Map" parameter is used, a bit number which corresponds to
each OPTIONAL or DEFAULT production is given as a comment.
3.5 Conventions used in state machines
3.5.1 State machine conventions for Type 28
The protocol sequences are described by means of state machines.
In state diagrams, states are represented as boxes, and state transitions are shown as arrows.
Names of states and transitions of the state diagram correspond to the names in the textual
listing of the state transitions.
The textual listing of the state transitions is structured as follows, see also Table 1.
– The first column contains the name or number of the transition.
– The second column defines the current state.
– The third column describes the condition of state transition and how it transits.
– Th
...