IEC 61158-4-2:2023
(Main)Industrial communication networks - Fieldbus specifications - Part 4-2: Data-link layer protocol specification - Type 2 elements
Industrial communication networks - Fieldbus specifications - Part 4-2: Data-link layer protocol specification - Type 2 elements
IEC 61158-4-2:2023 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:
- 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.
Réseaux de communication industriels - Spécifications des bus de terrain - Partie 4-2: Spécification du protocole de la couche liaison de données - Éléments de type 2
L'IEC 61158-4-2:2023 appartient à la série de normes visant à faciliter l’interconnexion des composants du système d’automatisation. Elle est liée aux autres normes de la série telle que définie par le modèle de référence de bus de terrain "à trois couches" décrit dans l’IEC 61158‑1.
Le protocole de liaison de données assure un service de liaison de données en s’appuyant sur les services offerts par la couche physique. Le présent document a pour principal objet de préciser un ensemble de règles de communication, exprimées sous la forme de procédures que doivent réaliser des entités de liaison de données homologues (DLE) au moment de la communication. Ces règles de communication ont pour vocation de fournir une base de développement stable visant à atteindre différents objectifs:
guider les implémenteurs et les concepteurs;
réaliser les essais et acquérir l’équipement;
dans un accord d’intégration des systèmes dans l’environnement de systèmes ouverts;
dans le cadre d’une meilleure compréhension des communications prioritaires au sein de l’OSI.
General Information
Relations
Overview
IEC 61158-4-2:2023 - part of the IEC 61158 fieldbus series - defines the data-link layer protocol specification (Type 2 elements) for industrial communication networks. Edition 5.0 (2023-03) specifies the procedures peer data-link entities (DLEs) must follow to provide reliable data-link services over a physical layer. The document is intended as a development, testing and procurement reference to enable interoperability, support time‑critical communications and guide implementers and system integrators in open automation environments.
Key topics and technical requirements
The standard covers the structure, encoding and operational rules for the data‑link layer without prescribing physical media specifics. Primary topics include:
- DLL architecture and services - functional classes, QoS considerations, and the DLL’s role in the three‑layer fieldbus reference model.
- DLPDU and Lpacket structure - definitions of Data‑Link Protocol Data Units (DLPDUs), Lpacket components and encoding conventions.
- Addressing - MAC ID, generic tag and fixed tag address formats used by DLEs.
- Media access and scheduling - access control machine (ACM), scheduled and unscheduled DLPDU handling, and moderator support.
- Services and procedures - connected and connectionless transfer services, queue maintenance, tag filters, link synchronization, synchronized parameter change and event reporting.
- Time and health mechanisms - time distribution Lpackets, tMinus/link parameters, “I’m‑alive” and ping mechanisms for synchronization and fault detection.
- Special Lpackets - UCMM (UnScheduled Connectionless Message Mode), keeper, TUI, WAMI, IP and Ethernet Lpackets, plus debug/reporting packets.
- DLL–PhL interface - required services and data‑encoding rules assumed from the physical layer.
- Station management objects - object models (e.g., ControlNet™ and Keeper objects), class/instance attributes, services and behavior to support network management, testing and commissioning.
- Conformance and applicability - guidelines for implementers, test houses and procurement to ensure interoperable equipment.
Practical applications and users
IEC 61158-4-2:2023 is used by:
- Device and gateway manufacturers implementing reliable data‑link protocols for field devices and controllers.
- System integrators and automation engineers designing deterministic, time‑critical industrial networks.
- Test laboratories and certification bodies for conformance testing and procurement specifications.
- OEMs and network architects seeking interoperability in multi‑vendor fieldbus environments.
- Standards committees and researchers analyzing fieldbus data‑link behaviors and QoS implications.
Related standards
- IEC 61158 series (other parts defining physical layer, application layer and mapping to the three‑layer fieldbus reference model)
- IEC 61158‑1 (reference models and overview of Type elements)
Keywords: IEC 61158-4-2, fieldbus, data-link layer, industrial communication networks, DLPDU, Lpacket, MAC ID, QoS, time-critical communications, station management.
Standards Content (Sample)
IEC 61158-4-2 ®
Edition 5.0 2023-03
INTERNATIONAL
STANDARD
colour
inside
Industrial communication networks – Fieldbus specifications –
Part 4-2: Data-link layer protocol specification – Type 2 elements
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IEC 61158-4-2 ®
Edition 5.0 2023-03
INTERNATIONAL
STANDARD
colour
inside
Industrial communication networks – Fieldbus specifications –
Part 4-2: Data-link layer protocol specification – Type 2 elements
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.040.40; 35.100.20; 35.110 ISBN 978-2-8322-6554-3
– 2 – IEC 61158-4-2:2023 © IEC 2023
CONTENTS
FOREWORD . 16
INTRODUCTION . 18
1 Scope . 19
1.1 General . 19
1.2 Specifications . 19
1.3 Procedures . 19
1.4 Applicability . 20
1.5 Conformance . 20
2 Normative references . 20
3 Terms, definitions, symbols, abbreviated terms and conventions . 22
3.1 Reference model terms and definitions . 22
3.2 Service convention terms and definitions . 24
3.3 Common terms and definitions . 24
3.4 Additional Type 2 definitions . 25
3.5 Type 2 symbols and abbreviated terms . 33
3.6 Conventions for station management objects . 34
4 Overview of the data-link protocol . 35
4.1 General . 35
4.1.1 DLL architecture . 35
4.1.2 Access control machine (ACM) and scheduling support functions . 37
4.1.3 Connection-mode, connectionless-mode data transfer and DL service . 37
4.2 Services provided by the DL . 37
4.2.1 Overview . 37
4.2.2 QoS . 38
4.3 Structure and definition of DL-addresses . 38
4.3.1 General . 38
4.3.2 MAC ID address . 39
4.3.3 Generic tag address . 40
4.3.4 Fixed tag address . 40
4.4 Services assumed from the PhL . 41
4.4.1 General requirements . 41
4.4.2 Data encoding rules . 41
4.4.3 DLL to PhL interface . 42
4.5 Functional classes . 44
5 General structure and encoding of PhIDUs and DLPDUs and related elements of
procedure . 44
5.1 Overview. 44
5.2 Media access procedure . 44
5.3 DLPDU structure and encoding . 48
5.3.1 General . 48
5.3.2 DLPDU components . 48
5.3.3 Preamble . 48
5.3.4 Start and end delimiters . 48
5.3.5 DLPDU octets and ordering . 48
5.3.6 Source MAC ID . 49
5.3.7 Lpackets field . 49
5.3.8 Frame check sequence (FCS) . 49
5.3.9 Null DLPDU . 52
5.3.10 Abort DLPDU . 52
5.4 Lpacket components . 52
5.4.1 General Lpacket structure. 52
5.4.2 Size . 53
5.4.3 Control . 53
5.4.4 Generic tag Lpackets . 53
5.4.5 Fixed tag Lpackets . 54
5.5 DLPDU procedures . 54
5.5.1 General . 54
5.5.2 Sending scheduled DLPDUs . 55
5.5.3 Sending unscheduled DLPDUs . 55
5.5.4 Receiving DLPDUs . 55
5.6 Summary of DLL support services and objects . 56
6 Specific DLPDU structure, encoding and procedures . 57
6.1 Modeling language . 57
6.1.1 State machine description. 57
6.1.2 Use of DLL- prefix . 58
6.1.3 Data types . 58
6.2 DLS user services . 59
6.2.1 General . 59
6.2.2 Connected mode and connectionless mode transfer service . 60
6.2.3 Queue maintenance service . 61
6.2.4 Tag filter service . 61
6.2.5 Link synchronization service . 62
6.2.6 Synchronized parameter change service. 62
6.2.7 Event reports service . 63
6.2.8 Bad FCS service . 64
6.2.9 Current moderator service . 64
6.2.10 Power up and online services . 64
6.2.11 Enable moderator service . 65
6.2.12 Listen only service . 65
6.3 Generic tag Lpacket . 65
6.3.1 General . 65
6.3.2 Structure of the generic-tag Lpacket . 65
6.3.3 Sending and receiving the generic-tag Lpacket . 66
6.4 Moderator Lpacket . 66
6.4.1 General . 66
6.4.2 Structure of the moderator Lpacket . 66
6.4.3 Sending and receiving the moderator Lpacket . 66
6.5 Time distribution Lpacket . 67
6.5.1 General . 67
6.5.2 Structure of the time distribution Lpacket . 67
6.5.3 Sending and receiving the time distribution Lpacket . 69
6.6 UCMM Lpacket . 70
6.6.1 General . 70
6.6.2 Structure of the UCMM Lpacket . 70
6.6.3 Sending and receiving the UCMM Lpacket . 70
6.7 Keeper UCMM Lpacket . 70
– 4 – IEC 61158-4-2:2023 © IEC 2023
6.7.1 General . 70
6.7.2 Structure of the Keeper UCMM Lpacket . 70
6.7.3 Sending and receiving the Keeper UCMM Lpacket . 70
6.8 TUI Lpacket . 71
6.8.1 General . 71
6.8.2 Structure of the TUI Lpacket . 71
6.8.3 Sending and receiving the TUI Lpacket . 72
6.9 Link parameters Lpacket and tMinus Lpacket . 72
6.9.1 General . 72
6.9.2 Structure of link parameters and tMinus Lpackets . 72
6.9.3 Sending and receiving the tMinus and Link parameters Lpackets . 73
6.10 I'm-alive Lpacket . 73
6.10.1 General . 73
6.10.2 Structure or the I'm-alive Lpacket . 73
6.10.3 Sending and receiving I'm Alive . 74
6.10.4 I'm alive state processing . 74
6.11 Ping Lpackets . 75
6.11.1 General . 75
6.11.2 Structure of the ping Lpackets . 76
6.11.3 Sending and receiving the ping Lpackets . 76
6.12 WAMI Lpacket. 76
6.12.1 General . 76
6.12.2 Structure of the WAMI Lpacket . 77
6.12.3 Sending and receiving the WAMI Lpacket . 77
6.13 Debug Lpacket . 77
6.14 IP Lpacket . 78
6.15 Ethernet Lpacket . 78
7 Objects for station management . 78
7.1 General . 78
7.2 ControlNet™ object . 80
7.2.1 Overview . 80
7.2.2 Class attributes . 80
7.2.3 Instance attributes . 80
7.2.4 Common services . 89
7.2.5 Class specific services . 90
7.2.6 Behavior . 91
7.2.7 Module status indicator . 91
7.3 Keeper object . 92
7.3.1 Overview . 92
7.3.2 Revision history . 92
7.3.3 Class attributes . 92
7.3.4 Instance attributes . 92
7.3.5 Common services . 101
7.3.6 Class specific services . 102
7.3.7 Service error codes . 108
7.3.8 Behavior . 108
7.3.9 Miscellaneous notes . 109
7.3.10 Keeper power up sequence . 110
7.4 Scheduling object . 115
7.4.1 Overview . 115
7.4.2 Class attributes . 116
7.4.3 Instance attributes . 116
7.4.4 Common services . 117
7.4.5 Class specific services . 119
7.4.6 Typical scheduling session . 125
7.5 TCP/IP Interface object . 126
7.5.1 Overview . 126
7.5.2 Revision history . 126
7.5.3 Class attributes . 126
7.5.4 Instance attributes . 127
7.5.5 Diagnostic connection points . 142
7.5.6 Common services . 142
7.5.7 Class specific services . 145
7.5.8 Behavior . 147
7.5.9 Address Conflict Detection (ACD) . 148
7.6 Ethernet Link object . 154
7.6.1 Overview . 154
7.6.2 Revision history . 154
7.6.3 Class attributes . 154
7.6.4 Instance attributes . 155
7.6.5 Diagnostic connection points . 165
7.6.6 Common services . 166
7.6.7 Class specific services . 167
7.6.8 Behavior . 168
7.7 DeviceNet™ object . 169
7.7.1 Overview . 169
7.7.2 Revision history . 170
7.7.3 Class attributes . 170
7.7.4 Instance attributes . 170
7.7.5 Common services . 177
7.7.6 Class specific services . 178
7.8 Connection Configuration object (CCO) . 179
7.8.1 Overview . 179
7.8.2 Revision history . 179
7.8.3 Class attributes . 179
7.8.4 Instance attributes . 181
7.8.5 Connection Configuration object change control . 190
7.8.6 Common services . 190
7.8.7 Class specific services . 196
7.8.8 Behavior . 200
7.9 DLR object . 200
7.9.1 Overview . 200
7.9.2 Revision history . 201
7.9.3 Class attributes . 201
7.9.4 Instance attributes . 201
7.9.5 Diagnostic connection points . 213
7.9.6 Common services . 213
7.9.7 Class specific services . 217
– 6 – IEC 61158-4-2:2023 © IEC 2023
7.10 QoS object . 218
7.10.1 Overview . 218
7.10.2 Revision History . 218
7.10.3 Class attributes . 218
7.10.4 Instance Attributes . 219
7.10.5 Common services . 220
7.11 Port object . 221
7.11.1 Overview . 221
7.11.2 Revision History . 221
7.11.3 Class attributes . 222
7.11.4 Instance attributes . 222
7.11.5 Common services . 229
7.12 PRP/HSR Protocol object . 231
7.12.1 Overview . 231
7.12.2 Revision history . 231
7.12.3 Class attributes . 231
7.12.4 Instance attributes . 231
7.12.5 Diagnostic connection points . 239
7.12.6 Common Services. 239
7.13 PRP/HSR Nodes Table object . 241
7.13.1 Overview . 241
7.13.2 Revision history . 241
7.13.3 Class attributes . 242
7.13.4 Instance attributes . 242
7.13.5 Common services . 244
7.14 LLDP Management object . 245
7.14.1 Overview . 245
7.14.2 Revision history . 245
7.14.3 Class attributes . 246
7.14.4 Instance attributes . 246
7.14.5 Common services . 247
7.15 LLDP Data Table object . 248
7.15.1 Overview . 248
7.15.2 Revision history . 249
7.15.3 Class attributes . 249
7.15.4 Instance attributes . 249
7.15.5 Common services . 253
8 Other DLE elements of procedure . 254
8.1 Network attachment monitor (NAM) . 254
8.1.1 General . 254
8.1.2 Default parameters . 256
8.1.3 Auto-addressing . 256
8.1.4 Valid MAC IDs . 257
8.1.5 State machine description. 257
8.2 Calculating link parameters . 263
8.2.1 Link parameters . 263
8.2.2 Conditions affecting link parameters . 263
8.2.3 Moderator change . 263
8.2.4 NUT timing . 264
8.2.5 Slot timing . 265
8.2.6 Blanking . 266
8.2.7 Example implementation . 266
9 Detailed specification of DL components . 271
9.1 General . 271
9.2 Access control machine (ACM) . 271
9.3 TxLLC . 290
9.4 RxLLC . 295
9.5 Transmit machine (TxM) . 298
9.6 Receive machine (RxM) . 302
9.7 Serializer . 308
9.8 Deserializer . 310
9.8.1 Octet construction . 310
9.8.2 FCS checking . 311
9.8.3 End of DLPDU processing . 311
9.9 DLL management . 311
10 Device Level Ring (DLR) protocol . 313
10.1 General . 313
10.2 Support for Multiple DLR Ring Pairs . 314
10.3 Supported topologies . 315
10.4 Overview of DLR operation . 316
10.4.1 Normal operation . 316
10.4.2 Link failures . 317
10.5 Classes of DLR implementation . 318
10.6 DLR behavior . 319
10.6.1 DLR variables . 319
10.6.2 Ring supervisor . 319
10.6.3 Ring node . 322
10.6.4 Sign on process . 323
10.6.5 Neighbor check process . 324
10.7 Implementation requirements . 324
10.7.1 Embedded switch requirements and recommendations . 324
10.7.2 DLR implementation requirements . 325
10.7.3 IEC 61588 and Type 2 Ethernet considerations . 326
10.7.4 IEEE Std 802.1Q-2018 STP/RSTP/MSTP considerations . 326
10.8 Using non-DLR nodes in the ring network . 326
10.8.1 General considerations . 326
10.8.2 Non-DLR end devices . 327
10.8.3 Non-DLR switches . 327
10.9 Redundant gateway devices on DLR network . 329
10.9.1 General . 329
10.9.2 Supported topologies . 330
10.9.3 Redundant gateway capable device . 330
10.9.4 Redundant gateway device behavior. 331
10.10 DLR messages . 334
10.10.1 General . 334
10.10.2 Common frame header . 335
10.10.3 Beacon frame . 336
10.10.4 Neighbor_Check request . 336
– 8 – IEC 61158-4-2:2023 © IEC 2023
10.10.5 Neighbor_Check_response . 337
10.10.6 Link_Status/Neighbor_Status . 337
10.10.7 Locate_Fault . 338
10.10.8 Announce . 338
10.10.9 Sign_On . 338
10.10.10 Advertise . 339
10.10.11 Flush_Tables . 339
10.10.12 Learning_Update . 340
10.11 State diagrams and state-event-action matrices . 340
10.11.1 Beacon-based ring node . 340
10.11.2 Announce-based ring node . 347
10.11.3 Ring supervisor . 351
10.11.4 Redundant gateway . 366
10.12 Performance analysis. 369
10.12.1 General . 369
10.12.2 Redundant gateway switchover performance . 373
11 PRP and HSR redundancy protocols . 375
11.1 General . 375
11.2 PRP overview . 375
11.2.1 General . 375
11.2.2 Address Conflict Detection (ACD) . 376
11.3 HSR overview . 377
12 LLDP protocol . 378
12.1 General . 378
12.2 LLDP overview . 379
12.3 Type 2 LLDP Transmission Requirements . 379
12.3.1 General . 379
12.3.2 Chassis ID TLV (TLV Type = 1) . 380
12.3.3 Port ID TLV (TLV Type = 2) . 380
12.3.4 System Capabilities TLV (TLV Type = 7) . 381
12.3.5 Management Address (TLV Type = 8) . 381
12.3.6 Type 2 Identification TLV (TLV Type = 127) . 381
12.3.7 Type 2 MAC Address TLV (TLV Type = 127) . 381
12.3.8 Type 2 Interface Label TLV (TLV Type = 127) . 381
12.3.9 Additional Ethernet Capabilities TLV (TLV Type = 127) . 382
12.4 Type 2 LLDP Reception Requirements . 382
12.5 Type 2 LLDP Reporting Requirements . 382
12.6 EtherNet/IP LLDP Link State Transition Requirements . 382
Annex A (normative) Indicators and switches . 383
A.1 Purpose . 383
A.2 Indicators . 383
A.2.1 General indicator requirements . 383
A.2.2 Common indicator requirements . 383
A.2.3 Fieldbus specific indicator requirements – option 1 . 385
A.2.4 Fieldbus specific indicator requirements – option 2 . 389
A.2.5 Fieldbus specific indicator requirements – option 3 . 393
A.3 Switches . 398
A.3.1 Common switch requirements . 398
A.3.2 Fieldbus specific switch requirements – option 1 . 398
A.3.3 Fieldbus specific switch requirements – option 2 . 398
A.3.4 Fieldbus specific switch requirements – option 3 . 399
Bibliography . 400
Figure 1 – Data-link layer internal architecture . 36
Figure 2 – Relationships of DLSAPs, DLSAP-addresses, and group DL-addresses . 39
Figure 3 – Basic structure of a MAC ID address . 39
Figure 4 – Basic structure of a generic tag address .
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Frequently Asked Questions
IEC 61158-4-2:2023 is a standard published by the International Electrotechnical Commission (IEC). Its full title is "Industrial communication networks - Fieldbus specifications - Part 4-2: Data-link layer protocol specification - Type 2 elements". This standard covers: IEC 61158-4-2:2023 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: - 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.
IEC 61158-4-2:2023 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: - 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.
IEC 61158-4-2:2023 is classified under the following ICS (International Classification for Standards) categories: 25.040.40 - Industrial process measurement and control; 35.100.20 - Data link layer; 35.110 - Networking. The ICS classification helps identify the subject area and facilitates finding related standards.
IEC 61158-4-2:2023 has the following relationships with other standards: It is inter standard links to IEC 61158-4-2:2019. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
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