IEC 61375-2-1:2012

Electronic railway equipment - Train communication network (TCN) - Part 2-1: Wire Train Bus (WTB)

IEC 61375-2-1:2012 applies to data communication in Open Trains, i.e. it covers data communication between consists of the said open trains and data communication within the consists of the said open trains.

Matériel électronique ferroviaire - Réseau embarqué de train (TCN) - Partie 2-1: Bus de Train Filaire (WTB)

La CEI 61375-2-1:2012 s'applique à la communication de données dans les Trains à Composition Variable, c'est-à-dire qu'elle couvre la communication de données aussi bien entre les rames que dans les rames desdits trains à composition variable.

General Information

• Status: Published
• Publication Date: 20-Jun-2012
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 45.060.01 - Railway rolling stock in general
• Technical Committee: TC 9 - Electrical equipment and systems for railways
• Drafting Committee: WG 43 - TC 9/WG 43
• Current Stage: PPUB - Publication issued
• Start Date: 21-Jun-2012
• Completion Date: 31-May-2012

Relations

• Replaces: IEC 61375-1:2007 - Electric railway equipment - Train bus - Part 1: Train communication network
• Effective Date: 05-Sep-2023

Overview

IEC 61375-2-1:2012 is an international standard published by the International Electrotechnical Commission (IEC) focused on electronic railway equipment. Specifically, it addresses the Train Communication Network (TCN) architecture, with Part 2-1 detailing the Wire Train Bus (WTB). This standard applies to data communication within and between consists of open trains, ensuring reliable and standardized data exchange for train control and monitoring systems. The WTB serves as a key communication backbone for train consists, enabling real-time, interoperable communication among on-board devices.

Key Topics

• Scope and Definitions
  The standard covers data communication protocols for the WTB in open train consists, including terminology, abbreviations, and conventions to ensure universal understanding and implementation.

• Physical Layer Specifications
  Details on the physical network topology, including bus sections, couplers, nodes, bus configuration rules, cable specifications, and shielding concepts. It also includes guidelines for node connections and transceiver requirements.

• Link Layer Control
  Specifications for data framing, telegram formats, addressing, medium allocation, and error handling within the WTB. This layer ensures efficient and error-free transmission of messages across the train bus.

• Real-Time Protocols
  Focuses on time-sensitive protocols essential for railway operations, including message services, protocol variables, presentation and encoding of transmitted data, and session management for reliable real-time communication.

• Inauguration and Network Management
  Defines procedures for automatic train composition detection and network topology configuration, critical for dynamic train consist changes and network integrity.

• Conformance Testing
  Requirements and methods to verify compliance with the standard, enabling interoperability and consistent performance across equipment from different manufacturers.

Applications

• Open Train Communication
  Facilitates standardized communication between train consists allowing data exchange related to control systems, diagnostics, and passenger information in modular open train configurations.

• On-Board Device Interoperability
  Enables diverse electronic components such as doors, brakes, HVAC, and control units to communicate seamlessly over the WTB, promoting integrated train control.

• Real-Time Train Monitoring and Control
  Supports real-time data transmission for operational safety, condition monitoring, and efficient maintenance scheduling.

• Dynamic Train Composition
  Assists in automatic recognition and configuration of varying consist arrangements through network inauguration protocols, crucial for flexible rail operations.

• Railway Manufacturers and Systems Integrators
  Provides technical requirements and reference for ensuring compatibility and performance of train communication networks during design, manufacturing, and integration.

Related Standards

• IEC 61375-1 – General architecture of Train Communication Network (TCN) outlining foundational concepts and layers.

• IEC 61375-3-x – Additional parts covering specific communication segments such as the Multifunction Vehicle Bus (MVB) and Ethernet Train Backbone.

• IEC 60571 – Electronic equipment standard for railway applications, related to reliability and quality assurance.

• EN 50155 – Railway rolling stock electronic equipment standards complementing data communication requirements.

• ISO/IEC 7498 – Reference model for Open Systems Interconnection (OSI), underlying many protocol architectural concepts applied in TCN.

---

Keywords: IEC 61375-2-1, Wire Train Bus, WTB, Train Communication Network, TCN, railway data communication, open trains, electronic railway equipment, real-time protocols, train consist communication, train network topology, railway interoperability, train control systems, IEC railway standards

Standards Content (Sample)

IEC 61375-2-1 ®
Edition 1.0 2012-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electronic railway equipment – Train communication network (TCN) –
Part 2-1: Wire Train Bus (WTB)

Matériel électronique ferroviaire – Réseau embarqué de train (TCN) –
Partie 2-1: Bus de Train Filaire (WTB)

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.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni
utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les
microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.
Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette
publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office Tel.: [phone]
3, rue de Varembé Fax: [phone]
CH-1211 Geneva 20 [e-mail]
Switzerland 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.

Useful links:
IEC publications search - www.iec.ch/searchpub Electropedia - www.electropedia.org
The advanced search enables you to find IEC publications The world's leading online dictionary of electronic and
by a variety of criteria (reference number, text, technical electrical terms containing more than 30 000 terms and
committee,…). definitions in English and French, with equivalent terms in
It also gives information on projects, replaced and additional languages. Also known as the International
withdrawn publications. Electrotechnical Vocabulary (IEV) on-line.

IEC Just Published - webstore.iec.ch/justpublished Customer Service Centre - webstore.iec.ch/csc
Stay up to date on all new IEC publications. Just Published If you wish to give us your feedback on this publication
details all new publications released. Available on-line and or need further assistance, please contact the
also once a month by email. Customer Service Centre: [e-mail].

A propos de la CEI
La Commission Electrotechnique Internationale (CEI) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications CEI
Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez
l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.

Liens utiles:
Recherche de publications CEI - www.iec.ch/searchpub Electropedia - www.electropedia.org
La recherche avancée vous permet de trouver des Le premier dictionnaire en ligne au monde de termes
publications CEI en utilisant différents critères (numéro de électroniques et électriques. Il contient plus de 30 000
référence, texte, comité d’études,…). termes et définitions en anglais et en français, ainsi que
Elle donne aussi des informations sur les projets et les les termes équivalents dans les langues additionnelles.
publications remplacées ou retirées. Egalement appelé Vocabulaire Electrotechnique
International (VEI) en ligne.
Just Published CEI - webstore.iec.ch/justpublished
Service Clients - webstore.iec.ch/csc
Restez informé sur les nouvelles publications de la CEI.
Just Published détaille les nouvelles publications parues. Si vous désirez nous donner des commentaires sur
Disponible en ligne et aussi une fois par mois par email. cette publication ou si vous avez des questions
contactez-nous: [e-mail].
IEC 61375-2-1 ®
Edition 1.0 2012-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electronic railway equipment – Train communication network (TCN) –

Part 2-1: Wire Train Bus (WTB)

Matériel électronique ferroviaire – Réseau embarqué de train (TCN) –

Partie 2-1: Bus de Train Filaire (WTB)

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XH
CODE PRIX
ICS 45.060 ISBN 978-2-88912-067-3

– 2 – 61375-2-1 ¤ IEC:2012
CONTENTS
FO REW O RD . 11
INT RODUCT ION . 13
1 Scope . 15
2 Normative references. 15
3 Terms and definitions, abbreviations, convent ions . 16
3.1 Terms and definitions . 16
3.2 Abbreviations . 32
3.3 Conventions . 34
3.3.1 Base of numeric values . 34
3.3.2 Naming conventions. 34
3.3.3 Time naming conventions . 34
3.3.4 Procedural interface conventions . 35
3.3.5 Specification of transmitted data . 37
3.3.6 State diagram conventions . 39
3.4 General considerations . 40
3.4.1 Interface between equipment . 40
3.4.2 Interface between c ons is ts . 40
3.4.3 Real-Time Protocols . 40
3.4.4 Network Management . 41
3.4.5 Configurations . 41
3.4.6 Structure of a standard device . 42
3.5 Conformance test . 45
4 Physical layer . 46
4.1 Topology . 46
4.1.1 Bus sections . 46
4.1.2 Couplers . 46
4.1.3 Nodes . 46
4.1.4 Consist orientation . 46
4.1.5 Consist specification (informal) . 47
4.2 Medium specifications . 48
4.2.1 Topology . 48
4.2.2 Duplicated medium (option) . 48
4.2.3 Bus Configuration rules . 49
4.2.4 Cable specification . 50
4.2.5 Shielding concept . 51
4.2.6 T erm inator . 52
4.3 Medium attachment . 53
4.3.1 Node connection points identification . 53
4.3.2 Direct node attachment . 53
4.3.3 Indirect node attachment . 54
4.3.4 Connector (optional) . 54
4.4 Node specifications . 55
4.4.1 Node elements. 55
4.4.2 Node and switch settings . 57
4.4.3 Duplicated Line Units (option) . 57
4.5 Line Unit specifications . 58

61375-2-1 ¤ IEC:2012 – 3 –
4.5.1 Galvanic separation . 58
4.5.2 Insertion losses of a Line Unit . 58
4.5.3 Switches specifications . 59
4.5.4 Shield connection to a Line Unit . 59
4.5.5 Fritting (option) . 60
4.6 Transceiver specifications. 61
4.6.1 Conventions . 61
4.6.2 Transmitter . 61
4.6.3 Receiver specifications . 64
4.7 Medium-dependent signalling . 66
4.7.1 Frame encoding and decoding . 66
4.7.2 Duplicated line handling (option) . 69
4.7.3 Line Unit interface . 71
5 Link Layer Control . 72
5.1 Addressing . 72
5.2 Frames and telegrams . 73
5.2.1 Frame_Data format . 73
5.2.2 Telegram timing . 74
5.2.3 Elements of the HDLC Frame. 76
5.2.4 Link Control Field . 77
5.2.5 Handling of ‘Attention’, ‘Change’ and ‘Inhibit’ . 80
5.2.6 Size, FCS and protocol errors . 80
5.3 Telegram formats and protocols . 80
5.3.1 Link Data field . 80
5.3.2 Process Data . 81
5.3.3 Message Data . 83
5.3.4 Supervisory Data . 84
5.3.5 Detection telegram . 85
5.3.6 Presence telegram . 87
5.3.7 Status telegram . 88
5.3.8 Set to Intermediate telegram . 90
5.3.9 Naming telegram . 91
5.3.10 Unname telegram . 93
5.3.11 Set to End telegram . 93
5.3.12 Topography telegram . 95
5.4 Medium allo c a tion . 97
5.4.1 Organisation . 97
5.4.2 Periodic Phase . 98
5.4.3 Sporadic phase . 99
5.5 Inauguration . 99
5.5.1 General . 99
5.5.2 Descriptors . 101
5.5.3 Detection of other compositions (informal) . 105
5.5.4 State diagrams of the inauguration . 108
5.6 Link layer interface . 148
5.6.1 Link layer layering . 148
5.6.2 Link Process_Data_Interface . 149
5.6.3 Link Message_Data_Interface . 150
5.6.4 Link management interface . 150

– 4 – 61375-2-1 ¤ IEC:2012
6 Real-Time protocols . 161
6.1 General . 161
6.1.1 Contents of this clause . 161
6.1.2 Structure of this clause . 162
6.2 Variables – Services and Protocols . 163
6.2.1 General . 163
6.2.2 Link layer Interface for Process_Data . 163
6.2.3 Application interface for Proc es s _ Variables . 169
6.3 Messages Services and Pr otoc ols . 184
6.3.1 General . 184
6.3.2 Reference station. 184
6.3.3 Message packets handling . 187
6.3.4 Message Link layer . 189
6.3.5 Message Network Layer . 199
6.3.6 Message transport layer . 211
6.3.7 Multicast Transport Protocol (option) . 242
6.3.8 Message session layer . 258
6.3.9 Message Presentation Layer . 260
6.3.10 Message Application layer . 260
6.4 Presentation and encoding of transmitted and stored data . 281
6.4.1 Purpose . 281
6.4.2 Data ordering . 282
6.4.3 Notation for the primitive types . 283
6.4.4 Structured types. 290
6.4.5 Alignment . 299
6.4.6 Notation for special types . 299
7 Application Layer . 301
7.1 Process Data Marshalling . 301
7.1.1 Marshalling Types . 301
7.1.2 Marshalling Modes . 301
7.1.3 Data Paths in PDM . 302
7.1.4 PDM Operation . 303
7.1.5 PDM Functions . 304
7.2 WTB Line Fault Location Detection . 306
7.2.1 Architecture . 307
7.2.2 Protocol Overview . 308
7.2.3 LFLD Sequence . 309
7.2.4 End Node State Machine (Testing Node) . 311
7.2.5 Intermediate Node State Machine (Segmenting Node) . 311
7.2.6 Disturbed Line selec tion . 311
7.2.7 Location Detection . 311
8 Train Network Management . 313
8.1 General . 313
8.1.1 Contents of this clause . 313
8.1.2 Structure of this clause . 314
8.2 Manager, Agents and in ter f ac es . 314
8.2.1 Manager and Agent . 314
8.2.2 Management messages protocol . 314
8.2.3 Interfaces . 315

61375-2-1 ¤ IEC:2012 – 5 –
8.3 Managed objects . 317
8.3.1 Object Attributes . 317
8.3.2 Station objects . 317
8.3.3 WTB link objec ts . 320
8.3.4 Variable objects . 321
8.3.5 Messenger objects . 323
8.3.6 Domain objects . 324
8.3.7 Task objects . 324
8.3.8 Clock object . 325
8.3.9 Journal object . 325
8.3.10 Equipment object . 326
8.4 Services and management messages . 326
8.4.1 Notation for all management messages . 326
8.4.2 Station services . 331
8.4.3 WTB link services . 338
8.4.4 Variables services . 350
8.4.5 Messages services . 360
8.4.6 Domain services . 369
8.4.7 Task services . 374
8.4.8 Clock services . 376
8.4.9 Journal Service . 377
8.4.10 Equipment Service . 379
8.5 Interface Procedures . 380
8.5.1 Manager interface (MGI) . 380
8.5.2 Agent interface . 381
Bibliography . 384

Figure 1 – Wire Train Bus . 13
Figure 2 – Layering of the TCN . 14
Figure 3 – State transition example . 39
Figure 4 – Interfaces between equipment . 40
Figure 5 – Interfaces between consists . 40
Figure 6 – Train Bus and Consist network . 41
Figure 7 – TCN configurations . 42
Figure 8 – TCN WTB device configuration options . 43
Figure 9 – Train Composition (two Intermediate Nodes shown) . 46
Figure 10 – Vehicle measurement . 47
Figure 11 – Connected nodes in regular operation . 48
Figure 12 – Double-line attachment . 49
Figure 13 – Grounded shield concept . 52
Figure 14 – Floating shield concept . 52
Figure 15 – Terminator . 53
Figure 16 – Direct node attachment (optional double-line) . 53
Figure 17 – Indirect attachment . 54
Figure 18 – WTB connector, front view . 55
Figure 19 – Example of MAU Structure . 56

– 6 – 61375-2-1 ¤ IEC:2012
Figure 20 – Node with redundant Line Units . 58
Figure 21 – Attenuation measurement . 59
Figure 22 – Shield grounding in the Line Unit . 60
Figure 23 – Fritting source and load . 60
Figure 24 – Transmitter fixtures . 62
Figure 25 – Pulse wave form at transmitter . 63
Figure 26 – Signal and idling at transmitter . 64
Figure 27 – Receiver signal envelope . 65
Figure 28 – Receiver edge distortion . 66
Figure 29 – Idealised frame on the line (16 bit Preamble shown) . 67
Figure 30 – Bit encoding. 67
Figure 31 – Preamble . 67
Figure 32 – End Delimit er . 68
Figure 33 – Valid frame, RxS, CS and SQE signals . 69
Figure 34 – Garbled frame, RxS, CS, SQE signals . 69
Figure 35 – Redundant Lines (as seen at a receiver) . 70
Figure 36 – Line_Disturbance signals . 71
Figure 37 – HDLC Frame structure . 73
Figure 38 – Telegram timing . 74
Figure 39 – Example of Interframe spacing . 75
Figure 40 – Frame spacing measured at the master side . 76
Figure 41 – Frame spacing at the slave . 76
Figure 42 – HDLC Data format . 77
Figure 43 – Format of HDLC Data . 77
Figure 44 – Process Data telegram . 81
Figure 45 – Format of Process Data Request . 82
Figure 46 – Format of Process Data Response . 83
Figure 47 – Message Data telegram . 83
Figure 48 – Format of Message Data Request . 83
Figure 49 – Format of Message Data Response . 84
Figure 50 – Supervisory telegram . 84
Figure 51 – Detection telegram. 85
Figure 52 – Format of Detect Request . 86
Figure 53 – Format of Detect Response . 86
Figure 54 – Presence telegram . 87
Figure 55 – Format of Presence Request . 87
Figure 56 – Format of Presence Response . 88
Figure 57 – Status telegram . 88
Figure 58 – Format of Status Request . 89
Figure 59 – Format of Status Response . 90
Figure 60 – Set-to-Intermediate telegram . 90
Figure 61 – Format of SetInt Request . 90
Figure 62 – Format of SetInt Response . 91

61375-2-1 ¤ IEC:2012 – 7 –
Figure 63 – Naming telegram . 91
Figure 64 – Format of Naming Request . 92
Figure 65 – Format of Naming Response . 92
Figure 66 – Unnaming telegram. 93
Figure 67 – Format of Unname Request . 93
Figure 68 – Set to End telegram . 93
Figure 69 – Format of SetEnd Request . 94
Figure 70 – Format of SetEnd Response . 94
Figure 71 – Topography telegram . 95
Figure 72 – Format of Topography Request . 95
Figure 73 – Format of Topography Response . 96
Figure 74 – Structure of the Basic Period . 97
Figure 75 – Node position numbering . 100
Figure 76 – Format of Node Descriptor . 101
Figure 77 – Format of Node Report . 102
Figure 78 – Format of User Report . 102
Figure 79 – Format of Composition St r ength . 103
Figure 80 – Master_Report . 104
Figure 81 – Format of Topo Counter . 104
Figure 82 – Format of Master Topo . 105
Figure 83 – Timing Diagram of detection protocol . 107
Figure 84 – Major node states and application settings . 108
Figure 85 – Node processes (End Setting) . 109
Figure 86 – AUXILIARY_PROCESS states . 115
Figure 87 – NAMING_RESPONSE macro . 116
Figure 88 – States of MAIN PROCESS . 117
Figure 89 – Macro ‘START_NODE’ . 120
Figure 90 – Procedure REQUEST_RESPONSE . 122
Figure 91 – Procedures ‘SET_TO_INT’ and ‘SET_TO_END’ . 123
Figure 92 – Macro ‘INIT_MASTER’ . 124
Figure 93 – Macro ‘NAMING_MASTER’ . 125
Figure 94 – Macro ASK_END . 126
Figure 95 – Procedure NAME_ONE . 129
Figure 96 – Macro TEACHING_MASTER . 131
Figure 97 – Macro ‘UNNAMING_MASTER’ . 132
Figure 98 – Macro ‘REGULAR_MASTER’ . 134
Figure 99 – Macro CHECK_DESC . 135
Figure 100 – Macro PERIODIC_POLL . 137
Figure 101 – Macro MESSAGE_POLL . 138
Figure 102 – States ‘UNNAMED_SLAVE’ . 140
Figure 103 – States ‘NAMED_SLAVE’ . 142
Figure 104 – Macro ‘LEARNING_SLAVE’. 144
Figure 105 – Macro ‘REGULAR_SLAVE’. 146

– 8 – 61375-2-1 ¤ IEC:2012
Figure 106 – Link layer layering . 148
Figure 107 – Structure of the Train Communication Network . 161
Figure 108 – Real-Time Protocols layering . 162
Figure 109 – LPI primitives exchange . 166
Figure 110 – Check_Variable . 171
Figure 111 – Individual access . 175
Figure 112 – Set access . 179
Figure 113 – Cluster access . 182
Figure 114 – Terminal station . 184
Figure 115 – Router station between WTB and MVB . 185
Figure 116 – Gateway station between WTB and Consist network . 186
Figure 117 – Packet format . 188
Figure 118 – Link layer data transmission . 190
Figure 119 – Link_Message_Data_Interface (LMI) . 191
Figure 120 – Example of MVB Message_Data frame . 192
Figure 121 – Example of WTB Message_Data frame . 193
Figure 122 – LMI primitives . 194
Figure 123 – Network layer on a Node . 200
Figure 124 – Encoding of the Network_Address . 203
Figure 125 – Building of the addresses in an outbound packet . 205
Figure 126 – Network address encoding on the train bus . 206
Figure 127 – Transport packet exchange . 213
Figure 128 – Packet formats (transport layer body) . 215
Figure 129 – State transition diagram of the MTP . 224
Figure 130 – Time-out SEND_TMO . 227
Figure 131 – Time-out ALIVE_TMO . 228
Figure 132 – Transport interface . 236
Figure 133 – Multicast message with no retransmission . 243
Figure 134 – Short multicast message with no BD packets and no loss . 244
Figure 135 – Exchange with lost packets . 245
Figure 136 – Packet formats . 247
Figure 137 – Protocol machine states . 248
Figure 138 – Session layer transfer . 259
Figure 139 – Session_Header in Call_Message (of type Am_Result) . 260
Figure 140 – Application_Messages_Interface . 261
Figure 141 – Encoding of AM_ADDRESS. . 265
Figure 142 – Process Data Marshalling . 301
Figure 143 – PDM Data Paths . 302
Figure 144 – PDM Operation . 304
Figure 145 – PDM Invalidate Variable or Function result . 304
Figure 146 – PDM Operation . 306
Figure 147 – PDM Validty check . 306
Figure 148 – LFLD Architecture . 307

61375-2-1 ¤ IEC:2012 – 9 –
Figure 149 – LFLD sequence . 309
Figure 150 – End node state machine . 311
Figure 151 – LFLD process, SN at node 63 . 312
Figure 152 – LFLD process, SN at node 1 . 312
Figure 153 – LFLD process, SN at node 1, attachment in direction 1 . 313
Figure 154 – Management messages . 315
Figure 155 – Agent Interface on a (gateway) Station .
...