IEC 61158-4-24:2019

IEC 61158-4-24 ®
Edition 2.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Industrial communication networks – Fieldbus specifications –
Part 4-24: Data-link layer protocol specification – Type 24 elements

Réseaux de communication industriels – Spécifications des bus de terrain –
Partie 4-24: Spécification du protocole de la couche liaison de données –
Eléments de type 24
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IEC 61158-4-24 ®
Edition 2.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Industrial communication networks – Fieldbus specifications –

Part 4-24: Data-link layer protocol specification – Type 24 elements

Réseaux de communication industriels – Spécifications des bus de terrain –

Partie 4-24: Spécification du protocole de la couche liaison de données –

Eléments de type 24
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.040.40; 35.100.20; 35.110 ISBN 978-2-8322-9159-7

– 2 – IEC 61158-4-24:2019 © IEC 2019
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 10
1.1 General . 10
1.2 Specifications . 10
1.3 Procedures . 10
1.4 Applicability . 11
1.5 Conformance . 11
2 Normative references . 11
3 Terms, definitions, symbols, abbreviations and conventions . 12
3.1 Reference model terms and definitions . 12
3.2 Service convention terms and definitions . 13
3.3 Common terms and definitions . 13
3.4 Symbols and abbreviations . 16
3.5 Additional Type 24 symbols and abbreviations . 17
3.6 Common Conventions . 17
3.7 Additional Type 24 conventions . 18
3.7.1 Primitive conventions . 18
3.7.2 State machine conventions . 18
4 Overview of DL-protocol . 19
4.1 Characteristic feature of the DL-protocol . 19
4.2 DL layer component . 20
4.2.1 Cyclic transmission control (CTC) . 21
4.2.2 Send Receive Control (SRC) . 21
4.2.3 DL-management . 21
4.3 Timing sequence. 21
4.3.1 Overview . 21
4.3.2 Cyclic transmission mode . 21
4.3.3 Acyclic transmission mode . 29
4.4 Service assumed from the PhL . 30
4.4.1 General requirement . 30
4.4.2 DL_Symbols . 30
4.4.3 Assumed primitives of the PhS . 30
4.5 Local parameters, variables, counters, timers . 30
4.5.1 Overview . 30
4.5.2 Variables, parameters, counters and timers to support DLE function . 31
5 DLPDU structure . 35
5.1 Overview . 35
5.1.1 Transfer syntax for bit sequences . 35
5.1.2 Data type encodings . 36
5.1.3 Frame format . 36
5.2 Basic format DLPDU structure . 36
5.2.1 General . 36
5.2.2 Synchronous frame . 40
5.2.3 Output data or Input data frame . 40
5.2.4 Delay measurement start frame . 41

5.2.5 Delay measurement frame . 41
5.2.6 Message token frame . 42
5.2.7 Status frame . 42
5.2.8 Cycle Information frame . 43
5.2.9 Message frame . 44
5.3 Short format DLPDU structure. 45
5.3.1 General . 45
5.3.2 Synchronous frame . 47
5.3.3 Output data or Input data frame . 48
5.3.4 Message frame . 49
6 DLE element procedure . 49
6.1 Overview . 49
6.2 Cyclic transmission control sublayer . 49
6.2.1 General . 49
6.2.2 DLS-user interface . 49
6.2.3 Protocol machines in CTC . 50
6.2.4 CTC-DLM interface . 101
6.3 Send Receive Control . 102
6.3.1 General . 102
6.3.2 SRC-CTC interface . 103
6.3.3 Detailed specification of SRC . 104
6.3.4 SRC-DLM interface . 108
7 DL-management layer (DLM) . 109
7.1 Overview . 109
7.2 Primitive definitions . 109
7.2.1 Primitives exchanged between DLMS-user and DLM . 109
7.2.2 Parameters used with DLM primitives . 110
7.3 DLM protocol machine . 110
7.3.1 C1 master . 110
7.3.2 Slave and C2 master . 115
7.4 Functions . 119
Bibliography . 122

Figure 1 – Data-link layer component . 21
Figure 2 – Timing chart of fixed-width time slot type cyclic communication . 22
Figure 3 – Timing chart of configurable time slot type cyclic communication . 24
Figure 4 – Schematic diagram of cyclic event occurrence . 26
Figure 5 – Timing relationship between cyclic transmission and data processing . 29
Figure 6 – Timing chart example of acyclic communication . 29
Figure 7 – Basic format DLPDU structure. 37
Figure 8 – Short format DLPDU structure . 45
Figure 9 – The state diagram of the C1 master for fixed-width time slot . 51
Figure 10 – The state diagram of the C2 master for fixed-width time slot . 58
Figure 11 – The state diagram of the slave for fixed-width time slot . 62
Figure 12 – The state diagram of the C1 master for configurable time slot . 65
Figure 13 – The state diagram of the C2 master for configurable time slot . 74
Figure 14 – The state diagram of slave for configurable time slot . 77

– 4 – IEC 61158-4-24:2019 © IEC 2019
Figure 15 – The state diagram of message initiator for basic format . 82
Figure 16 – The state diagram of message responder for basic format . 86
Figure 17 – The state diagram of message initiator for short format . 90
Figure 18 – The state diagram of message responder for short format . 94
Figure 19 – The state diagram of the acyclic transmission protocol machine . 100
Figure 20 – Internal architecture of one-port SRC . 104
Figure 21 – Internal architecture of multi-port SRC . 104
Figure 22 – Internal architecture of serializer . 105
Figure 23 – Internal architecture of deserializer . 106
Figure 24 – State diagram of the C1 master DLM . 111
Figure 25 – State diagram of the Slave and the C2 master DLM . 116

Table 1 – State transition descriptions . 18
Table 2 – Description of state machine elements . 19
Table 3 – Conventions used in state machines . 19
Table 4 – Characteristic features of the fieldbus data-link protocol . 20
Table 5 – List of the values of the variable Cyc_sel . 31
Table 6 – List of the values of the variable Tunit . 32
Table 7 – List of the values of the variable PDUType . 33
Table 8 – List of the values of the variable SlotType . 34
Table 9 – Transfer syntax for bit sequences . 36
Table 10 – Bit order . 36
Table 11 – Destination and Source address format . 37
Table 12 – Station address . 37
Table 13 – Extended address . 38
Table 14 – Message control field format (Information transfer format) . 38
Table 15 – Message control field format (Supervisory format) . 38
Table 16 – The list of Supervisory function bits . 39
Table 17 – Frame type and data length format . 39
Table 18 – The list of Frame type. 39
Table 19 – Data format of the Synchronous frame . 40
Table 20 – The field list of the Synchronous frame . 40
Table 21 – Data format of the Output data or the Input data frame . 40
Table 22 – The field list of the Output data or the Input data frame . 41
Table 23 – Data format of Delay measurement start frame . 41
Table 24 – The field list of Delay measurement start frame . 41
Table 25 – Data format of Delay measurement frame. 42
Table 26 – The field list of Delay measurement frame . 42
Table 27 – Data format of Status frame. 42
Table 28 – The field list of Status frame . 43
Table 29 – The list of the DLE status . 43
Table 30 – The list of Repeater status . 43
Table 31 – Data format of Delay measurement frame. 44

Table 32 – The field list of Cycle Information frame. 44
Table 33 – Data format of Message frame . 44
Table 34 – The field list of Message frame . 45
Table 35 – Range of Station address field. 46
Table 36 – Control field format (I/O data exchange format) . 46
Table 37 – Control field format (Message format) . 46
Table 38 – The field list of Message format . 47
Table 39 – Data format of the Synchronous frame . 47
Table 40 – The field list of the Synchronous frame . 48
Table 41 – Data format of the Output data frame . 48
Table 42 – The field list of the Output data frame . 48
Table 43 – Data format of the Input data frame . 48
Table 44 – The field list of the Input data frame . 48
Table 45 – Primitives and parameters for the DLS-user interface issued by the DLS-
user . 49
Table 46 – Primitives and parameters for the DLS-user interface issued by the CTC . 50
Table 47 – The state table of the C1 master for fixed-width time slot . 52
Table 48 – The state table of the C2 master for fixed-width time slot . 59
Table 49 – The state table of the slave for fixed-width time slot . 63
Table 50 – The state table of the C1 master for configurable time slot . 66
Table 51 – The state table of the C2 master for configurable time slot . 75
Table 52 – The state table of slave for configurable time slot . 78
Table 53 – The list of functions used by cyclic transmission machine . 79
Table 54 – The state table of message initiator for basic format . 82
Table 55 – The state table of message responder for basic format . 86
Table 56 – The state table of message initiator for short format . 90
Table 57 – The state table of message responder for short format . 95
Table 58 – List of functions used by the message segmentation machine . 99
Table 59 – The state table of the acyclic transmission protocol machine . 101
Table 60 – The list of functions used acyclic transmission protocol machine . 101
Table 61 – Primitives and parameters exchanged between CTC and DLM . 102
Table 62 – Error event primitive and parameters . 102
Table 63 – primitives and parameters for SRC-CTC interface . 103
Table 64 – Send frame primitive and parameters . 103
Table 65 – Receive frame primitives and parameters . 104
Table 66 – Primitives and parameters exchanged between SRC and DLM . 108
Table 67 – Get value primitive and parameters . 109
Table 68 – Error event primitive and parameters . 109
Table 69 – The list of primitives and parameters (DLMS-user source) . 110
Table 70 – The list of primitives and parameters (DLM source) . 110
Table 71 – State table of the C1 Master DLM . 112
Table 72 – State table of the Slave and the C2 master DLM . 117
Table 73 – The list of the functions used by DLM protocol machine . 120

– 6 – IEC 61158-4-24:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 4-24: Data-link layer protocol specification –
Type 24 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
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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
consensus of opinion on the relevant subjects since each technical committee has representation from all
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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
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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
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
Attention is drawn to the fact that the use of the associated protocol type is restricted by its
intellectual-property-right holders. In all cases, the commitment to limited release of
intellectual-property-rights made by the holders of those rights permits a layer protocol type to
be used with other layer protocols of the same type, or in other type combinations explicitly
authorized by its intellectual-property-right holders.
NOTE Combinations of protocol types are specified in IEC 61784-1 and IEC 61784-2.
International Standard IEC 61158-4-24 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 technical changes with respect to the previous
edition:
• patent declaration in the Introduction;
• corrections on transmission sequence of fixed-width time slot type in 4.3.2;
• technical extension for band sharing between I/O data exchange and message
communication; and
• spelling and grammar.
The text of this International Standard is based on the following documents:
FDIS Report on voting
65C/946/FDIS 65C/955/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 61158 series, published under the general title Industrial
communication networks – Fieldbus specifications, can be found on the IEC web site.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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 61158-4-24:2019 © IEC 2019
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 61158-1.
The data-link protocol provides the data-link service by making use of the services available
from the physical 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 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.
This standard 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 may
work together in any combination.
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 profile series. Use of the various protocol types in other combinations
may require permission from their respective intellectual-property-right holders.
The International Electrotechnical Commission (IEC) draws attention to the fact that it is
claimed that compliance with this document may involve the use of patents as follows, where
the [xx] notation indicates the holder of the patent right:
US 8223804 [YE] COMMUNICATION DEVICE, SYNCHRONIZED
JP 4760978 SYSTEM, AND SYNCHRONIZED COMMUNICATION METHOD
CN 200880002225.3
DE 602008046644.2
US 7769935 [YE] MASTER SLAVE COMMUNICATION SYSTEM AND MASTER
JP 4683346 SLAVE COMMUNICATION METHOD
US 8046512
DE 602007041530.6
JP 4356698 [YE] COMMUNICATION DEVICE, SYNCHRONIZED COMMUNICATION
SYSTEM, AND SYNCHRONIZED COMMUNICATION METHOD
IEC takes no position concerning the evidence, validity and scope of this patent right.
The holders of these patent rights have assured IEC that they are willing to negotiate licenses
either free of charge or under reasonable and non-discriminatory terms and conditions with
applicants throughout the world. In this respect, the statement of the holders of these patent
rights is registered with IEC. Information may be obtained from
[YE] YASKAWA ELECTRIC CORPORATION
2-1 Kurosakishiroishi, Yahatanishi-ku, Kitakyushu 806-0004, Japan
Attention; Intellectual Property Rights Section.

Attention is drawn to the possibility that some of the elements of this document may be the
subject of patent rights other than those identified above. IEC shall not be held responsible for
identifying any or all such patent rights.
ISO (www.iso.org/patents) and IEC (http://patents.iec.ch) maintain on-line data bases of
patents relevant to their standards. Users are encouraged to consult the data bases for the
most up to date information concerning patents.

– 10 – IEC 61158-4-24:2019 © IEC 2019
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 4-24: Data-link layer protocol specification –
Type 24 elements
1 Scope
1.1 General
The data-link layer provides basic time-critical messaging communications between devices in
an automation environment.
This protocol provides communication opportunities to all participating data-link entities:
a) in a synchronously-starting cyclic manner, according to a pre-established schedule, or
b) in an acyclic manner, as requested by each of those data-link entities.
Thus this protocol can be characterized as one which provides cyclic and acyclic access
asynchronously but with a synchronous restart of each cycle.
1.2 Specifications
This document specifies
a) procedures for the timely transfer of data and control information from one data-link user
entity to a peer user entity, and among the data-link entities forming the distributed
datalink service provider;
b) procedures for giving communications opportunities to all participating DL-entities (DLEs),
sequentially and in a cyclic manner for deterministic and synchronized transfer at cyclic
intervals up to 64 ms;
c) procedures for giving communication opportunities available for time-critical data
transmission together with non-time-critical data transmission without prejudice to the
time-critical data transmission;
d) procedures for giving cyclic and acyclic communication opportunities for time-critical data
transmission with prioritized access;
e) procedures for giving communication opportunities based on ISO/IEC/IEEE 8802-3
medium access control, with provisions for nodes to be added or removed during normal
operation;
f) the structure of the fieldbus DLPDUs used for the transfer of data and control information
by the protocol of this document, and their representation as physical interface data units.
1.3 Procedures
The procedures are defined in terms of
a) the interactions between peer DL-entities through the exchange of fieldbus DLPDUs;
b) the interactions between a DL-service (DLS) provider and a DLS-user in the same system
through the exchange of DLS primitives;
c) the interactions between a DLS-provider and a Ph-service provider in the same system
through the exchange of Ph-service primitives.

1.4 Applicability
These procedures are applicable to instances of communication between systems which
support time-critical communications services within the data-link layer of the OSI or fieldbus
reference models, and which require the ability to interconnect in an open systems
interconnection environment.
Profiles provide a simple multi-attribute means of summarizing an implementation’s
capabilities, and thus its applicability to various time-critical communications needs.
1.5 Conformance
This document also specifies conformance requirements for systems implementing these
procedures. This document does not contain tests to demonstrate compliance with such
requirements.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
NOTE All parts of the IEC 61158 series, as well as IEC 61784-1 and IEC 61784-2 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 61158-2, Industrial communication networks – Fieldbus specifications – Part 2: Physical
layer specification and service definition
IEC 61158-3-24:2014, Industrial communication networks – Fieldbus specifications –
Part 3-24: Data-link layer service definition – Type 24 elements
ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference
Model: The Basic Model
ISO/IEC 7498-3, Information technology – Open Systems Interconnection – Basic Reference
Model: Naming and addressing
ISO/IEC/IEEE 8802-3:2017, Information technology – Telecommunications and information
exchange between systems – Local and metropolitan area networks – Specific requirements –
Part 3: Standard for Ethernet
ISO/IEC 9899, Information technology – Programming languages – C
ISO/IEC 10731, Information technology – Open Systems Interconnection – Basic Reference
Model – Conventions for the definition of OSI services
ISO/IEC 13239:2002, Information technology – Telecommunications and information
exchange between systems – High-level data link control (HDLC) procedures
ISO/IEC 19501:2005, Information technology – Open Distributed Processing – Unified
Modelling Language (UML) Version 1.4.2

– 12 – IEC 61158-4-24:2019 © IEC 2019
3 Terms, definitions, symbols, abbreviations and conventions
For the purposes of this document, the following terms, definitions, symbols, abbreviations
and conventions 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 Reference model terms and definitions
This document is based in part on the concepts developed in ISO/IEC 7498-1 and
ISO/IEC 7498-3, and makes use of the following terms defined therein.
3.1.1 acknowledgement [ISO/IEC 7498-1]
3.1.2 correspondent (N)-entities [ISO/IEC 7498-1]
correspondent DL-entities (N=2)
correspondent Ph-entities (N=1)
3.1.3 DL-address [ISO/IEC 7498-3]
3.1.4 DL-protocol [ISO/IEC 7498-1]
3.1.5 DL-protocol-data-unit [ISO/IEC 7498-1]
3.1.6 DL-service-data-unit [ISO/IEC 7498-1]
3.1.7 DLS-user [ISO/IEC 7498-1]
3.1.8 DLS-user-data [ISO/IEC 7498-1]
3.1.9 Event [ISO/IEC 19501]
3.1.10 layer-management [ISO/IEC 7498-1]
3.1.11 primitive name [ISO/IEC 7498-1]
3.1.12 Reset [ISO/IEC 7498-1]
3.1.13 Segmenting [ISO/IEC 7498-1]
3.1.14 State [ISO/IEC 19501]
3.1.15 state machine [ISO/IEC 19501]
3.1.16 systems-management [ISO/IEC 7498-1]
3.1.17 Transition [ISO/IEC 19501]
3.1.18 (N)-entity [ISO/IEC 7498-1]
DL-entity (N=2)
Ph-entity (N=1)
3.1.19 (N)-layer [ISO/IEC 7498-1]
DL-layer (N=2)
Ph-layer (N=1)
(N)-service [ISO/IEC 7498-1]
DL-service (N=2)
Ph-service (N=1)
(N)-service-access-point [ISO/IEC 7498-1]
DL-service-access-point (N=2)
Ph-service-access-point (N=1)
3.2 Service convention terms and definitions
This document also makes use of the following terms defined in ISO/IEC 10731 as they apply
to the data-link layer:
3.2.1 confirm (primitive)
3.2.2 DL-service-primitive
3.2.3 DL-service-provider
3.2.4 DL-service-user
3.2.5 indication (primitive)
3.2.6 request (primitive)
3.2.7 requestor
3.2.8 response (primitive)
3.3 Common terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.3.1
acyclic transmission
non-periodic exchange of telegrams
3.3.2
C1 master
one of the station type that initiates and controls cyclic transmission
3.3.3
C1 message
message communication that C1 master operates as initiator to exchange messages with
slave or C2 master
3.3.4
C2 master
one of the station type that has the function of monitoring all process data transmitte
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