IEC 61158-4-3:2007

IEC 61158-4-3
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 4-3: Data-link layer protocol specification – Type 3 elements

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form

or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,

please contact the address below or your local IEC member National Committee for further information.

IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: inmail@iec.ch
Web: www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
ƒ Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
ƒ IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
ƒ Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
ƒ Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: csc@iec.ch
Tel.: +41 22 919 02 11
Fax: +41 22 919 03 00
IEC 61158-4-3
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 4-3: Data-link layer protocol specification – Type 3 elements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XH
ICS 35.100.20; 25.040.40 ISBN 2-8318-9429-8

– 2 – 61158-4-3 © IEC:2007(E)
CONTENTS
FOREWORD.6

INTRODUCTION.8

1 Scope.9

1.1 General .9

1.2 Specifications.9

1.3 Procedures.9

1.4 Applicability.9

1.5 Conformance.10
2 Normative references .10
3 Terms, definitions, symbols and abbreviations.10
3.1 Reference model terms and definitions.10
3.2 Service convention terms and definitions.12
3.3 Common terms and definitions .13
3.4 Additional Type 3 definitions.15
3.5 Common symbols and abbreviations .17
3.6 Type 3 symbols and abbreviations.18
4 Common DL-protocol elements.22
4.1 Frame check sequence .22
5 Overview of the DL-protocol .24
5.1 General .24
5.2 Overview of the medium access control and transmission protocol .25
5.3 Transmission modes and DL-entity.26
5.4 Service assumed from the PhL .31
5.5 Operational elements .34
5.6 Cycle and system reaction times .50
6 General structure and encoding of DLPDUs, and related elements of procedure .53
6.1 DLPDU granularity .53
6.2 Length octet (LE, LEr) .54
6.3 Address octet .55
6.4 Control octet (FC).57
6.5 DLPDU content error detection.61
6.6 DATA_UNIT .62

6.7 Error control procedures.62
7 DLPDU-specific structure, encoding and elements of procedure .64
7.1 DLPDUs of fixed length with no data field.64
7.2 DLPDUs of fixed length with data field.65
7.3 DLPDUs with variable data field length.67
7.4 Token DLPDU .68
7.5 ASP DLPDU .69
7.6 SYNCH DLPDU .69
7.7 Time Event (TE) DLPDU.69
7.8 Clock Value (CV) DLPDU .69
7.9 Transmission procedures .70
8 Other DLE elements of procedure.73
8.1 DL-entity initialization .73
8.2 States of the media access control of the DL-entity .73

61158-4-3 © IEC:2007(E) – 3 –
8.3 Clock synchronization protocol .79

Annex A (normative) – DL-Protocol state machines .84

A.1 Overall structure.84

A.2 Variation of state machines in different devices .85

A.3 DL Data Resource .86

A.4 FLC / DLM.91

A.5 MAC.115

A.6 SRU .143

Annex B (informative) – Type 3 (synchronous): exemplary FCS implementations. 161

Annex C (informative) – Type 3: Exemplary token procedure and message transfer
periods .163
C.1 Procedure of token passing .163
C.2 Examples for token passing procedure . 164
C.3 Examples for message transfer periods – asynchronous transmission.169
C.4 Examples for message transfer periods – synchronous transmission. 170
Bibliography.171

Figure 1 – Relationships of DLSAPs, DLSAP-addresses and group DL-addresses .14
Figure 2 – Logical token-passing ring .27
Figure 3 – PhL data service for asynchronous transmission .31
Figure 4 – Idle time T .37
ID1
Figure 5 – Idle time T (SDN, CS) .37
ID2
Figure 6 – Idle time T (MSRD) .38
ID2
Figure 7 – Slot time T .38
SL1
Figure 8 – Slot time T .39
SL2
Figure 9 – Slot time T .44
SL1
Figure 10 – Slot time T .44
SL2
Figure 11 – Token transfer period .50
Figure 12 – Message transfer period.51
Figure 13 – UART character .53
Figure 14 – Octet structure .54
Figure 15 – Length octet coding.54

Figure 16 – Address octet coding.55
Figure 17 – DAE/SAE octet in the DLPDU.56
Figure 18 – Address extension octet .56
Figure 19 – FC octet coding for send/request DLPDUs .57
Figure 20 – FC octet coding for acknowledgement or response DLPDUs .58
Figure 21 – FCS octet coding.61
Figure 22 – Data field .62
Figure 23 – Ident user data.62
Figure 24 – DLPDUs of fixed length with no data field.64
Figure 25 – DLPDUs of fixed length with no data field.65
Figure 26 – DLPDUs of fixed length with data field .66
Figure 27 – DLPDUs of fixed length with data field .66

– 4 – 61158-4-3 © IEC:2007(E)
Figure 28 – DLPDUs with variable data field length.67

Figure 29 – DLPDUs with variable data field length.68

Figure 30 – Token DLPDU .68

Figure 31 – Token DLPDU .69

Figure 32 – Send/request DLPDU of fixed length with no data .70

Figure 33 – Token DLPDU and send/request DLPDU of fixed length with data.70

Figure 34 – Send/request DLPDU with variable data field length.71

Figure 35 – Send/request DLPDU of fixed length with no data .71

Figure 36 – Token DLPDU and send/request DLPDU of fixed length with data.72
Figure 37 – Send/request DLPDU with variable data field length.72
Figure 38 – DL-state-diagram .74
Figure 39 – Overview of clock synchronization.80
Figure 40 – Time master state machine .81
Figure 41 – Time receiver state machine .82
Figure 42 – Clock synchronization .83
Figure A.1 – Structuring of the protocol machines.85
Figure A.2 – Structure of the SRU Machine.144
Figure B.1 – Example of FCS generation for Type 3 (synchronous) . 161
Figure B.2 – Example of FCS syndrome checking on reception for Type 3
(synchronous) .161
Figure C.1 – Derivation of the token holding time (T ).164
TH
Figure C.2 – No usage of token holding time (T ).165
TH
Figure C.3 – Usage of token holding time (T ) for message transfer (equivalence
TH
between T of each Master station) .166
TH
Figure C.4 – Usage of token holding time (T ) in different working load situations . 168
TH
Table 1 – FCS length, polynomials and constants by Type 3 synchronous .23
Table 2 – Characteristic features of the fieldbus data-link protocol.25
Table 3 – Transmission function code .59
Table 4 – FCB, FCV in responder .61
Table 5 – Operating parameters .73

Table A.1 – Assignment of state machines.86
Table A.2 – Data resource .87
Table A.3 – Primitives issued by DL-User to FLC.91
Table A.4 – Primitives issued by FLC to DL-User.91
Table A.5 – Primitives issued by DL-User to DLM .93
Table A.6 – Primitives issued by DLM to DL-User .94
Table A.7 – Parameters used with primitives exchanged between DL-User and FLC.94
Table A.8 – Parameters used with primitives exchanged between DL-User and DLM .95
Table A.9 – FLC/DLM state table .96
Table A.10 – FLC / DLM function table.109
Table A.11 – Primitives issued by DLM to MAC.116
Table A.12 – Primitives issued by MAC to DLM.116

61158-4-3 © IEC:2007(E) – 5 –
Table A.13 – Parameters used with primitives exchanged between DLM and MAC . 116

Table A.14 – Local MAC variables .117

Table A.15 – MAC state table .117

Table A.16 – MAC function table.139

Table A.17 – Primitives issued by DLM to SRC.145

Table A.18 – Primitives issued by SRC to DLM.146

Table A.19 – Primitives issued by MAC to SRC.146

Table A.20 – Primitives issued by SRC to MAC.146

Table A.21 – Parameters used with primitives exchanged between MAC and SRC .147
Table A.22 – FC structure.147
Table A.23 – Local variables of SRC.147
Table A.24 – SRC state table.148
Table A.25 – SRC functions .160

– 6 – 61158-4-3 © IEC:2007(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
INDUSTRIAL COMMUNICATION NETWORKS –

FIELDBUS SPECIFICATIONS –
Part 4-3: Data-link layer protocol specification – Type 3 elements

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
NOTE  Use of some of the associated protocol types is restricted by their intellectual-property-right holders. In all
cases, the commitment to limited release of intellectual-property-rights made by the holders of those rights permits
a particular data-link layer protocol type to be used with physical layer and application layer protocols in Type

combinations as specified explicitly in the IEC 61784 series. Use of the various protocol types in other
combinations may require permission from their respective intellectual-property-right holders.
IEC draws attention to the fact that it is claimed that compliance with this standard may involve the use of patents
as follows, where the [xx] notation indicates the holder of the patent right:
Type 3 and possibly other types:
DE 36 43 979 C2 [SI] Deterministisches Zugriffsverfahren nach dem Tokenprinzip für eine
Datenübertragung
DE 36 43 979 A1 [SI] Deterministisches Zugriffsverfahren nach dem Tokenprinzip für eine
Datenübertragung
IEC takes no position concerning the evidence, validity and scope of these patent rights.
The holders of these patent rights have assured IEC that they are willing to negotiate licences 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 are registered with IEC. Information may be obtained from:
[SI]: SIEMENS AG
Ludwig Winkel
Siemensallee 84
D-76181 Karlsruhe
Germany
61158-4-3 © IEC:2007(E) – 7 –
Attention is drawn to the possibility that some of the elements of this standard 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.

International Standard IEC 61158-4-3 has been prepared by subcommittee 65C: Industrial

networks, of IEC technical committee 65: Industrial-process measurement, control and

automation.
This first edition and its companion parts of the IEC 61158-4 subseries cancel and replace

IEC 61158-4:2003. This edition of this part constitutes an editorial revision.

This edition of IEC 61158-4 includes the following significant changes from the previous

edition:
a) deletion of the former Type 6 fieldbus, and the placeholder for a Type 5 fieldbus data link

layer, for lack of market relevance;
b) addition of new types of fieldbuses;
c) division of this part into multiple parts numbered -4-1, -4-2, …, -4-19.
The text of this standard is based on the following documents:
FDIS Report on voting
65C/474/FDIS 65C/485/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under http://webstore.iec.ch in the
data related to the specific publication. At this date, the publication will be:
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
NOTE  The revision of this standard will be synchronized with the other parts of the IEC 61158 series.
The list of all the parts of the IEC 61158 series, under the general title Industrial
communication networks – Fieldbus specifications, can be found on the IEC web site.

– 8 – 61158-4-3 © IEC:2007(E)
INTRODUCTION
This part of IEC 61158 is one of a series produced to facilitate the interconnection of

automation system components. It is related to other standards in the set as defined by the

“three-layer” fieldbus reference model described in IEC/TR 61158-1.

The data-link protocol provides the data-link service by making use of the services available

from the physical layer. The primary aim of this standard is to provide a set of rules for

communication expressed in terms of the procedures to be carried out by peer 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 implementors 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 standard together with other standards
positioned within the OSI or fieldbus reference models, otherwise incompatible systems may
work together in any combination.

61158-4-3 © IEC:2007(E) – 9 –
INDUSTRIAL COMMUNICATION NETWORKS –

FIELDBUS SPECIFICATIONS –
Part 4-3: Data-link layer protocol specification – Type 3 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 a pre-selected “master” subset of data-
link entities in a cyclic asynchronous manner, sequentially to each of those data-link entities.
Other data-link entities communicate only as permitted and delegated by those master data-
link entities.
For a given master, its communications with other data-link entities can be cyclic, or acyclic
with prioritized access, or a combination of the two.
This protocol provides a means of sharing the available communication resources in a fair
manner. There are provisions for time synchronization and for isochronous operation.
1.2 Specifications
This standard 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 data-
link service provider;
b) the structure of the fieldbus DLPDUs used for the transfer of data and control information
by the protocol of this standard, 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 (DLEs) 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.

– 10 – 61158-4-3 © IEC:2007(E)

1.5 Conformance
This standard also specifies conformance requirements for systems implementing these

procedures. This standard does not contain tests to demonstrate compliance with such

requirements.
2 Normative references
The following referenced documents are indispensable for the application of this standard. For

dated references, only the edition cited applies. For undated references, the latest edition of

the referenced document (including any amendments) applies.

IEC 61158-2 (Ed.4.0), Digital data communications for measurement and control – Fieldbus
for use in industrial control systems – Part 2: Physical layer specification and service
definition
IEC 61158-3-3, Digital data communications for measurement and control – Fieldbus for use
in industrial control systems – Part 3-3: Data link service definition – Type 3 elements
ISO/IEC 2022, Information technology – Character code structure and extension techniques
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 10731, Information technology – Open Systems Interconnection – Basic Reference
Model – Conventions for the definition of OSI services
ISO 1177, Information processing – Character structure for start/stop and synchronous
character oriented transmission
3 Terms, definitions, symbols and abbreviations
For the purposes of this standard, the following terms, definitions, symbols and abbreviations
apply.
3.1 Reference model terms and definitions

This standard 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 called-DL-address [7498-3]
3.1.2 calling-DL-address [7498-3]
3.1.3 centralized multi-end-point-connection [7498-1]
3.1.4 correspondent (N)-entities [7498-1]
correspondent DL-entities  (N=2)
correspondent Ph-entities  (N=1)
3.1.5 demultiplexing [7498-1]
3.1.6 DL-address [7498-3]
61158-4-3 © IEC:2007(E) – 11 –

3.1.7 DL-address-mapping [7498-1]

3.1.8 DL-connection [7498-1]
3.1.9 DL-connection-end-point [7498-1]

3.1.10 DL-connection-end-point-identifier [7498-1]

3.1.11 DL-connection-mode transmission [7498-1]

3.1.12 DL-connectionless-mode transmission [7498-1]

3.1.13 DL-data-sink [7498-1]
3.1.14 DL-data-source [7498-1]
3.1.15 DL-duplex-transmission [7498-1]
3.1.16 DL-facility [7498-1]
3.1.17 DL-local-view [7498-3]
3.1.18 DL-name [7498-3]
3.1.19 DL-protocol [7498-1]
3.1.20 DL-protocol-connection-identifier [7498-1]
3.1.21 DL-protocol-control-information [7498-1]
3.1.22 DL-protocol-data-unit [7498-1]
3.1.23 DL-protocol-version-identifier [7498-1]
3.1.24 DL-relay [7498-1]
3.1.25 DL-service-connection-identifier [7498-1]
3.1.26 DL-service-data-unit [7498-1]
3.1.27 DL-simplex-transmission [7498-1]
3.1.28 DL-subsystem [7498-1]
3.1.29 DL-user-data [7498-1]
3.1.30 flow control [7498-1]
3.1.31 layer-management [7498-1]
3.1.32 multiplexing [7498-3]
3.1.33 naming-(addressing)-authority [7498-3]
3.1.34 naming-(addressing)-domain [7498-3]
3.1.35 naming-(addressing)-subdomain [7498-3]
3.1.36 (N)-entity [7498-1]
DL-entity
Ph-entity
3.1.37 (N)-interface-data-unit [7498-1]
DL-service-data-unit  (N=2)
Ph-interface-data-unit  (N=1)

– 12 – 61158-4-3 © IEC:2007(E)

3.1.38 (N)-layer [7498-1]
DL-layer  (N=2)
Ph-layer  (N=1)
3.1.39 (N)-service [7498-1]
DL-service  (N=2)
Ph-service  (N=1)
3.1.40 (N)-service-access-point [7498-1]
DL-service-access-point  (N=2)

Ph-service-access-point  (N=1)

3.1.41 (N)-service-access-point-address [7498-1]
DL-service-access-point-address  (N=2)
Ph-service-access-point-address  (N=1)
3.1.42 peer-entities [7498-1]
3.1.43 Ph-interface-control-information [7498-1]
3.1.44 Ph-interface-data [7498-1]
3.1.45 primitive name [7498-3]
3.1.46 reassembling [7498-1]
3.1.47 recombining [7498-1]
3.1.48 reset [7498-1]
3.1.49 responding-DL-address [7498-3]
3.1.50 routing [7498-1]
3.1.51 segmenting [7498-1]
3.1.52 sequencing [7498-1]
3.1.53 splitting [7498-1]
3.1.54 synonymous name [7498-3]
3.1.55 systems-management [7498-1]

3.2 Service convention terms and definitions

This standard also makes use of the following terms defined in ISO/IEC 10731 as they apply
to the data-link layer:
3.2.1 acceptor
3.2.2 asymmetrical service
3.2.3 confirm (primitive);
requestor.deliver (primitive)
3.2.4 deliver (primitive)
3.2.5 DL-confirmed-facility
3.2.6 DL-facility
3.2.7 DL-local-view
61158-4-3 © IEC:2007(E) – 13 –

3.2.8 DL-mandatory-facility
3.2.9 DL-non-confirmed-facility

3.2.10 DL-provider-initiated-facility

3.2.11 DL-provider-optional-facility

3.2.12 DL-service-primitive;
primitive
3.2.13 DL-service-provider
3.2.14 DL-service-user
3.2.15 DL-user-optional-facility
3.2.16 indication (primitive)
acceptor.deliver (primitive)
3.2.17 multi-peer
3.2.18 request (primitive);
requestor.submit (primitive)
3.2.19 requestor
3.2.20 response (primitive);
acceptor.submit (primitive)
3.2.21 submit (primitive)
3.2.22 symmetrical service
3.3 Common terms and definitions
NOTE  Many definitions are common to more than one protocol Type; they are not necessarily used by all protocol
Types.
3.3.1
DL-segment, link, local link
single DL-subnetwork in which any of the connected DLEs may communicate directly, without
any intervening DL-relaying, whenever all of those DLEs that are participating in an instance
of communication are simultaneously attentive to the DL-subnetwork during the period(s) of
attempted communication
3.3.2
DLSAP
distinctive point at which DL-services are provided by a single DL-entity to a single higher-
layer entity
NOTE  This definition, derived from ISO/IEC 7498-1, is repeated here to facilitate understanding of the critical
distinction between DLSAPs and their DL-addresses. (See Figure 1.)

– 14 – 61158-4-3 © IEC:2007(E)

DLS-user-entity
DLS-user-entity
DLS-users
DLSAP DLSAP DLSAP
DLSAP-
address DLSAP-
DLSAP-
group DL-
address
addresses
address
DL-layer
DL-entity
PhSA P PhSA P
Ph-layer
NOTE 1  DLSAPs and PhSAPs are depicted as ovals spanning the boundary between two adjacent layers.
NOTE 2  DL-addresses are depicted as designating small gaps (points of access) in the DLL portion of a DLSAP.
NOTE 3  A single DL-entity may have multiple DLSAP-addresses and group DL-addresses associated with a
single DLSAP.
Figure 1 – Relationships of DLSAPs, DLSAP-addresses and group DL-addresses

3.3.3
DL(SAP)-address
either an individual DLSAP-address, designating a single DLSAP of a single DLS-user, or a
group DL-address potentially designating multiple DLSAPs, each of a single DLS-user.
NOTE  This terminology is chosen because ISO/IEC 7498-3 does not permit the use of the term DLSAP-address to
designate more than a single DLSAP at a single DLS-user
3.3.4
(individual) DLSAP-address
DL-address that designates only one DLSAP within the extended link

NOTE  A single DL-entity may have multiple DLSAP-addresses associated with a single DLSAP.
3.3.5
extended link
DL-subnetwork, consisting of the maximal set of links interconnected by DL-relays, sharing a
single DL-name (DL-address) space, in which any of the connected DL-entities may
communicate, one with another, either directly or with the assistance of one or more of those
intervening DL-relay entities
NOTE  An extended link may be composed of just a single link.
3.3.6
frame
denigrated synonym for DLPDU
61158-4-3 © IEC:2007(E) – 15 –

3.3.7
group DL-address
DL-address that potentially designates more than one DLSAP within the extended link. A

single DL-entity may have multiple group DL-addresses associated with a single DLSAP. A

single DL-entity also may have a single group DL-address associated with more than one

DLSAP
3.3.8
node
single DL-entity as it appears on one local link

3.3.9
receiving DLS-user
DL-service user that acts as a recipient of DL-user-data
NOTE  A DL-service user can be concurrently both a sending and receiving DLS-user.
3.3.10
sending DLS-user
DL-service user that acts as a source of DL-user-data
3.4 Additional Type 3 definitions
3.4.1
acknowledge DLPDU
reply DLPDU that contains no DLSDU
3.4.2
address extension
DLSAP address or region/segment address
3.4.3
bit time
time to transmit one bit
3.4.4
confirmed message exchange
complete data transfer with request and acknowledgement or response DLPDU
3.4.5
controller_type
hardware class of the communications entity

3.4.6
current master
token holder
3.4.7
data DLPDU
DLPDU that carries a DLSDU from a local DLS-user to a remote DLS-user
3.4.8
DL_status
status that specifies the result of the execution of the associated request
3.4.9
GAP
range of station (DLE) DL-addresses from this station (TS) to its successor (NS) in the logical
token ring, excluding stations above HSA

– 16 – 61158-4-3 © IEC:2007(E)

3.4.10
GAP maintenance
registration of new Master and slave stations

3.4.11
isochronous mode
special operational mode that implies both a constant (isochronous) cycle with a fixed

schedule of high and low priority messages, and the synchronization of the DLS-users with

this constant (isochronous) cycle

3.4.12
local DLS-user
DLS-user that initiates the current service
3.4.13
message exchange
complete confirmed or unconfirmed data transfer
3.4.14
region/segment address
address extension that identifies a particular fieldbus subnetwork
NOTE  This supports DL-routing between fieldbusses.
3.4.15
request data
DLSDU provided by the remote DLS-user to the local DLS-user
3.4.16
remote DLE
addressed DLE of a service request (that is, the intended receiving DLE of any resulting
send/request DLPDU)
3.4.17
remote DLS-user
addressed DLS-user of a service request (that is, the intended receiver of any resulting
indication primitive)
3.4.18
reply DLPDU
DLPDU transmitted from a remote DLE to the initiating (local) DLE, and possibly other DLEs
NOTE  When the remote DLE is a Publisher, the reply DLPDU also can be sent to several remote DLEs.

3.4.19
response DLPDU
reply DLPDU that carries a DLSDU from a remote DLS-user to local DLS-user
3.4.20
send data
DLSDU provided by a local DLS-user to a remote DLS-user
3.4.21
send/request DLPDU
DLPDU that carries either a request for data or a DLSDU or both from a local DLS-user to a
remote DLS-user
61158-4-3 © IEC:2007(E) – 17 –

3.4.22
time master
device which is able to send clock synchronization DLPDUs

NOTE  Link devices have time master functionality.

3.4.23
time receiver
device which is able to be time synchronized by a time Master

3.4.24
token holder
Master station that controls bus access
3.4.25
token passing
medium access method, in which the right to transmit is passed from master station to master
station in a logical ring
3.5 Common symbols and abbreviations
3.5.1 Data units
3.5.1.1 DLPDU DL-protocol data unit
3.5.1.2 DLSDU DL-service data unit
3.5.1.3 PhIDU
Ph-interface data unit
3.5.1.4 PhPDU Ph-protocol data unit

3.5.2 Miscellaneous
3.5.2.1 DL-
data link layer (as a prefix)
3.5.2.2 DLCEP DL-connection endpoint
3.5.2.3 DLE
DL-entity (the local active instance of the Data Link layer)
3.5.2.4 DLL DL-layer
3.5.2.5 DLM-
DL-management (as a prefix)
3.5.2.6 DLMS DL-management-service

3.5.2.7 DLS
DL-service
3.5.2.8 DLSAP DL-service access point
3.5.2.9 FIFO
first-in first-out (queuing method)
3.5.2.10 LLC logical link control
3.5.2.11 MAC
medium access control
3.5.2.12 OSI open systems interconnection
3.5.2.13 Ph- physical layer (as a prefix)
3.5.2.14 PhE Ph-entity (the local active instance of the Physical layer)
3.5.2.15 PhL
Ph-layer
– 18 – 61158-4-3 © IEC:2007(E)

3.5.2.16 PhS Ph-service
3.5.2.17 PhSAP Ph-service access point

3.5.2.18 QoS quality of service

3.6 Type 3 symbols and abbreviations

3.6.1 ACK acknowledge(ment) DLPDU

3.6.2 ASM active spare time message

3.6.3 ASP active spare time period
3.6.4 Bus ID bus identification, an address extension (region/DL-segment
address) that identifies a particular bus as supporting routing
between DL-segments
3.6.5 CRX character receive execution
3.6.6 CS clock synchronization
3.6.7 CTX character transmit execution
3.6.8 DA destination address of a DLPDU
3.6.9 DAE destination address extension(s) of a DLPDU, which convey
D_SAP_index and/or destination bus ID
3.6.10 D_SAP destination service access point, the DLSAP associated with the
remote DLS-user
3.6.11 D_SAP_index destination service access point index – that component of a
DLSAP address which designates a DLSAP and remote DLS-
user within the remote DLE
3.6.12 DXM data exchange multicast
3.6.13 ED end delimiter of a DLPDU
3.6.14 EOA END-OF-ACTIVITY
3.6.15 EOD END-OF-DATA
3.6.16 EODA END-OF-DATA-AND-ACTIVITY

3.6.17 EXT address extension bit of a DLPDU
3.6.18 FC frame control (frame type) field of a DLPDU
3.6.19 FCB frame count bit of a DLPDU (FC field) used to eliminate lost or
duplicated DLPDUs
3.6.20 FCV frame count bit valid bit of a DLPDU, indicates whether the FCB
is to be evaluated
3.6.21 FCS frame check sequence (synchronous) o
...