SIST EN IEC 61375-1:2026
(Main)Electronic railway equipment - Train communication network (TCN) - Part 1: General architecture
Electronic railway equipment - Train communication network (TCN) - Part 1: General architecture
IEC 61375-1:2026 applies to the architecture of data communication systems in open trains, i.e. it covers the architecture of a communication system for the data communication between vehicles of the said open trains, the data communication within the vehicles and the data communication from train to the ground. The applicability of IEC 61375-1 to the train network technologies allows for interoperability of individual vehicles within open trains in international traffic. The data communication systems inside vehicles are given as recommended solutions to cope with the said TCN. In any case, proof of compatibility between a proposed train backbone and a proposed consist network will have to be brought by the supplier. IEC 61375-1 might be additionally applicable to closed trains and multiple unit trains when so agreed between purchaser and supplier. This fourth edition cancels and replaces the third edition published in 2012. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) Extension of train backbone topologies: aggregated and segregated topology;
b) Added independent consist orientation check with segregated train backbone topology;
c) Introduction of wireless technologies: wireless train backbone and wireless consist network;
d) Possibility of virtual networks;
e) Definition of data classes and protocol requirements suitable for the OMTS domain;
f) New clause about cybersecurity in train communication networks.
Elektronische Betriebsmittel für Bahnen - Zug-Kommunikations-Netzwerk (TCN) - Teil 1: Allgemeiner Aufbau
Matériel électronique ferroviaire - Réseau embarqué de train (TCN) - Partie 1: Architecture générale
L'IEC 61375-1:2026 s’applique à l’architecture des systèmes de communication de données dans les trains à composition variable, c’est-à-dire qu’elle couvre l’architecture d’un système de communication de données entre les véhicules des trains considérés, les communications de données dans les véhicules et les communications de données train-sol. L'application de IEC 61375-1 aux technologies de réseau de train permet l'interopérabilité de véhicules individuels dans des trains à composition variable en trafic international. Les systèmes de communication de données dans les véhicules sont donnés comme solutions recommandées pour fonctionner avec ledit TCN. Dans tous les cas, le fournisseur devra apporter la preuve de la compatibilité entre un réseau central de train proposé et un réseau de rame proposé. Par ailleurs, IEC 61375-1 pourrait s'appliquer aux rames non modifiables et aux trains à unités multiples après accord entre acheteur et fournisseur. Cette quatrième édition annule et remplace la troisième édition publiée en 2012. Cette édition constitue une révision technique.
Cette édition inclut également les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) Extension des topologies de réseau central de train: topologie agrégée et séparée
b) Ajout d'une vérification indépendante de l'orientation de la rame avec une topologie séparée de réseau central de train
c) Introduction des technologies sans fil: réseau central de train sans fil et réseau de rame sans fil
d) Possibilité de réseaux virtuels
e) Définition des classes de données et des exigences de protocole adaptées au domaine OMTS
f) Nouvel article sur la cybersécurité dans les réseaux embarqués de train
Železniške elektronske naprave - Komunikacijsko omrežje vlaka (TCN) - 1. del: Splošna arhitektura
IEC 61375-1:2026 se nanaša na arhitekturo sistemov za prenos podatkov v odprtih vlakih, tj. pokriva arhitekturo komunikacijskega sistema za prenos podatkov med vozili omenjenih odprtih vlakov, prenos podatkov znotraj vozil in prenos podatkov z vlaka na tla. Uporabnost IEC 61375-1 za tehnologije omrežij vlakov omogoča interoperabilnost posameznih vozil znotraj odprtih vlakov v mednarodnem prometu. Sistemi za prenos podatkov znotraj vozil so podani kot priporočene rešitve za obvladovanje omenjenega TCN (vlakovno komunikacijsko omrežje). V vsakem primeru bo moral dobavitelj dokazati združljivost med predlaganim hrbteničnim omrežjem vlaka in predlaganim omrežjem sestave. IEC 61375-1 je lahko dodatno uporabljiv za zaprte vlake in vlake z več enotami, če se tako dogovorita kupec in dobavitelj. Ta četrta izdaja preklicuje in nadomešča tretjo izdajo, objavljeno leta 2012. Ta izdaja predstavlja tehnično revizijo.
Ta izdaja vključuje naslednje pomembne tehnične spremembe glede na prejšnjo izdajo:
a) Razširitev topologij hrbteničnega omrežja vlaka: združena in ločena topologija;
b) Dodan neodvisen pregled orientacije sestave z ločeno topologijo hrbteničnega omrežja vlaka;
c) Uvedba brezžičnih tehnologij: brezžično hrbtenično omrežje vlaka in brezžično omrežje sestave;
d) Možnost virtualnih omrežij;
e) Določitev razredov podatkov in zahtev protokola, primernih za področje OMTS (operativni vlakovni telekomunikacijski sistem);
f) Nov člen o kibernetski varnosti v vlakovnih komunikacijskih omrežjih.
General Information
- Status
- Published
- Public Enquiry End Date
- 31-Jan-2025
- Publication Date
- 21-May-2026
- Technical Committee
- ŽEN - Electrical applications for railways
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 12-May-2026
- Due Date
- 17-Jul-2026
- Completion Date
- 22-May-2026
Relations
- Effective Date
- 28-Apr-2026
- Effective Date
- 28-Apr-2026
- Effective Date
- 28-Apr-2026
- Effective Date
- 28-Apr-2026
- Effective Date
- 28-Apr-2026
- Effective Date
- 28-Apr-2026
- Effective Date
- 28-Apr-2026
- Effective Date
- 23-Jan-2023
Overview
SIST EN IEC 61375-1:2026 specifies the general architecture of Train Communication Networks (TCN) for electronic railway equipment, focusing on open trains but also applicable to closed and multiple unit trains by agreement. The standard outlines fundamental aspects regarding the data communication systems connecting railway vehicles, within vehicles, and between trains and ground infrastructure. This fourth edition introduces several technical updates, enhancing interoperability, cybersecurity, and the adoption of modern communication technologies like wireless and virtual networks.
The standard is developed by the Slovenski inštitut za standardizacijo (SIST) and aligns with International Electrotechnical Commission (IEC) guidelines, ensuring global relevance. By defining the TCN architecture, the standard enables seamless communication and system integration across international and mixed vehicle fleets, contributing to safe, reliable, and efficient railway operations.
Key Topics
Main Elements Covered:
- TCN Hierarchical Structure: Defines two core levels - the train backbone (interconnecting vehicles) and consist networks (within individual consists).
- Network Topologies: Extension to include aggregated and segregated backbone topologies, supporting greater flexibility in train compositions.
- Wireless Technologies: Introduction of wireless train backbone and wireless consist networks, reflecting technological advancements.
- Virtual Networks: Guidelines for the implementation and operation of virtual networking solutions within train communication systems.
- Interoperability: Framework for compatibility and proof between train backbones and consist networks, critical for international and multi-vendor interoperability.
- Data Classes & Protocols: Definitions tailored for onboard multimedia and telematics services (OMTS) as well as operational data handling.
- Cybersecurity: A dedicated new clause addressing threat prevention, detection, system integrity, network segmentation, authentication, authorization, and protection of data in transit.
Technical Changes from Previous Edition:
- Aggregated and segregated train backbone topologies
- Independent consist orientation check for segregated backbone
- Wireless communication support for backbone and consist networks
- Introduction of virtual networks
- Data class and protocol requirements for OMTS
- Comprehensive guidelines for cybersecurity in TCNs
Applications
Practical Uses of SIST EN IEC 61375-1:2026:
- Railway Fleet Modernization: Supports the integration of new vehicles into existing fleets, regardless of manufacturer, by guaranteeing interoperable network communication.
- International Operations: Facilitates seamless operation of railway vehicles across country borders and between various operators by adhering to a common communication architecture.
- System Upgrades: Lays out the requirements and recommendations for upgrading legacy networks and deploying new wired or wireless communication solutions in trains.
- Cybersecurity Management: Assists operators and suppliers in implementing robust cybersecurity measures to safeguard critical train communication networks from cyber threats.
- Operational Efficiency: Enables implementation of reliable, scalable, and adaptive communication systems, improving maintenance, diagnostic, and operational workflows.
Related Standards
- IEC 61375 Series: Comprehensive set of standards detailing specific technologies and protocols for train communication networks.
- EN TS 50701: Technical specification focusing on cybersecurity applicable to railway applications.
- IEC 62443-4-2: Addresses security for industrial automation and control systems, referenced for essential function and cybersecurity definitions.
- IEEE 802.1Q: Specifies standards for local and metropolitan area networks, including VLANs relevant to the networking part of TCNs.
Railway operators, system integrators, and suppliers are encouraged to reference these and related documents when designing, implementing, or assessing train communication networks in accordance with SIST EN IEC 61375-1:2026.
Get Certified
Connect with accredited certification bodies for this standard
BSI Group
BSI (British Standards Institution) is the business standards company that helps organizations make excellence a habit.
IRIS Certification (UNIFE)
International Railway Industry Standard certification.
TÜV SÜD Rail GmbH
TÜV SÜD railway certification services.
Sponsored listings
Frequently Asked Questions
SIST EN IEC 61375-1:2026 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Electronic railway equipment - Train communication network (TCN) - Part 1: General architecture". This standard covers: IEC 61375-1:2026 applies to the architecture of data communication systems in open trains, i.e. it covers the architecture of a communication system for the data communication between vehicles of the said open trains, the data communication within the vehicles and the data communication from train to the ground. The applicability of IEC 61375-1 to the train network technologies allows for interoperability of individual vehicles within open trains in international traffic. The data communication systems inside vehicles are given as recommended solutions to cope with the said TCN. In any case, proof of compatibility between a proposed train backbone and a proposed consist network will have to be brought by the supplier. IEC 61375-1 might be additionally applicable to closed trains and multiple unit trains when so agreed between purchaser and supplier. This fourth edition cancels and replaces the third edition published in 2012. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) Extension of train backbone topologies: aggregated and segregated topology; b) Added independent consist orientation check with segregated train backbone topology; c) Introduction of wireless technologies: wireless train backbone and wireless consist network; d) Possibility of virtual networks; e) Definition of data classes and protocol requirements suitable for the OMTS domain; f) New clause about cybersecurity in train communication networks.
IEC 61375-1:2026 applies to the architecture of data communication systems in open trains, i.e. it covers the architecture of a communication system for the data communication between vehicles of the said open trains, the data communication within the vehicles and the data communication from train to the ground. The applicability of IEC 61375-1 to the train network technologies allows for interoperability of individual vehicles within open trains in international traffic. The data communication systems inside vehicles are given as recommended solutions to cope with the said TCN. In any case, proof of compatibility between a proposed train backbone and a proposed consist network will have to be brought by the supplier. IEC 61375-1 might be additionally applicable to closed trains and multiple unit trains when so agreed between purchaser and supplier. This fourth edition cancels and replaces the third edition published in 2012. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) Extension of train backbone topologies: aggregated and segregated topology; b) Added independent consist orientation check with segregated train backbone topology; c) Introduction of wireless technologies: wireless train backbone and wireless consist network; d) Possibility of virtual networks; e) Definition of data classes and protocol requirements suitable for the OMTS domain; f) New clause about cybersecurity in train communication networks.
SIST EN IEC 61375-1:2026 is classified under the following ICS (International Classification for Standards) categories: 35.240.60 - IT applications in transport; 45.020 - Railway engineering in general; 45.060.01 - Railway rolling stock in general. The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN IEC 61375-1:2026 has the following relationships with other standards: It is inter standard links to SIST EN 62580-1:2017, SIST EN 61375-3-4:2014, SIST EN 61375-2-1:2012, SIST EN 61375-3-3:2012, SIST EN 61375-2-3:2016, SIST EN 62625-2:2017, SIST EN IEC 63341-1:2026, SIST EN 61375-1:2012. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
SIST EN IEC 61375-1:2026 is associated with the following European legislation: EU Directives/Regulations: 2008/57/EC, 2016/797/EU, 2016/797/EU, 2016/797/EU, 2016/797/EU, 2016/797/EU, 2016/797/EU, 2016/797/EU, 2016/797/EU, 2016/797/EU, 2016/797/EU, 2016/797/EU, 2016/797/EU; Standardization Mandates: M/483, M/591. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
SIST EN IEC 61375-1:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2026
Železniške elektronske naprave - Komunikacijsko omrežje vlaka (TCN) - 1. del:
Splošna arhitektura
Electronic railway equipment - Train communication network (TCN) - Part 1: General
architecture
Elektronische Betriebsmittel für Bahnen - Zug-Kommunikations-Netzwerk (TCN) - Teil 1:
Allgemeiner Aufbau
Matériel électronique ferroviaire - Réseau embarqué de train (TCN) - Partie 1:
Architecture générale
Ta slovenski standard je istoveten z: EN IEC 61375-1:2026
ICS:
35.240.60 Uporabniške rešitve IT v IT applications in transport
prometu
45.060.01 Železniška vozila na splošno Railway rolling stock in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN IEC 61375-1
NORME EUROPÉENNE
EUROPÄISCHE NORM April 2026
ICS 45.060.01 Supersedes EN 61375-1:2012
English Version
Electronic railway equipment - Train communication network
(TCN) - Part 1: General architecture
(IEC 61375-1:2026)
Matériel électronique ferroviaire - Réseau embarqué de Elektronische Betriebsmittel für Bahnen - Zug-
train (TCN) - Partie 1: Architecture générale Kommunikations-Netzwerk (TCN) - Teil 1: Allgemeiner
(IEC 61375-1:2026) Aufbau
(IEC 61375-1:2026)
This European Standard was approved by CENELEC on 2026-04-09. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61375-1:2026 E
European foreword
The text of document 9/3252/FDIS, future edition 4 of IEC 61375-1, prepared by TC 9 "Electrical
equipment and systems for railways" was submitted to the IEC-CENELEC parallel vote and approved
by CENELEC as EN IEC 61375-1:2026.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-04-30
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-04-30
document have to be withdrawn
This document supersedes EN 61375-1:2012 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a standardization request addressed to CENELEC by the
European Commission. The Standing Committee of the EFTA States subsequently approves these
requests for its Member States.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61375-1:2026 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 62580 (series) NOTE Approved as EN 62580 (series)
IEC 62443 (series) NOTE Approved as EN IEC 62443-4-2:2019/AC:2022-09 (series)
IEC 61375-1 ®
Edition 4.0 2026-03
INTERNATIONAL
STANDARD
Electronic railway equipment - Train communication network (TCN) -
Part 1: General architecture
ICS 45.060.01 ISBN 978-2-8327-1057-9
IEC 61375-1:2026-03(en)
IEC 61375-1:2026 © IEC 2026
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions, abbreviated terms, acronyms, and conventions . 8
3.1 Terms and definitions. 8
3.2 Abbreviations and acronyms . 16
3.3 Conventions . 17
3.3.1 Base of numeric values . 17
3.3.2 Naming conventions . 17
3.3.3 State diagram conventions . 17
4 Basic architecture . 17
4.1 General . 17
4.2 Technology and components . 18
4.2.1 Technology classes . 18
4.2.2 Component types . 18
4.3 Hierarchical structure . 18
4.3.1 Network levels . 18
4.3.2 Train backbone level . 19
4.3.3 Consist network level . 19
4.3.4 Interface between train backbone and consist network . 20
4.3.5 End devices connected to train backbone . 21
4.4 Network configurations . 21
4.5 Train to ground connection (option) . 22
5 Train backbone . 23
5.1 General . 23
5.2 Train backbone topology . 23
5.2.1 General . 23
5.2.2 Train backbone based on bus technology . 23
5.2.3 Train backbone based on switched technology . 24
5.2.4 Train Backbone based on wireless technology . 25
5.3 Train compositions . 27
5.4 Train backbone node numbering . 27
5.5 Train directions . 28
5.5.1 Vehicle . 28
5.5.2 Consist . 28
5.5.3 Closed train . 29
5.5.4 Train . 29
5.6 Train inauguration . 31
5.6.1 Objectives . 31
5.6.2 Node sequence and orientation discovery . 31
5.6.3 Train network directory . 31
5.6.4 Train directory . 31
5.6.5 Train inauguration control . 34
5.6.6 Node states . 35
5.6.7 Node roles . 38
IEC 61375-1:2026 © IEC 2026
5.6.8 Performance . 38
5.6.9 Independent consist orientation check (Option) . 38
6 Consist network . 39
6.1 General . 39
6.2 Scope of standardization. 39
6.3 Consist network topology . 40
6.3.1 Consist network based on bus technology (MVB, CCN) . 40
6.3.2 Consist network based on switched technology (ECN) . 41
6.3.3 Consist network based on wireless technology (WLCN) . 43
6.3.4 Sub-networks . 43
6.3.5 Heterogeneous consist network . 44
6.4 Gateway . 44
6.4.1 General . 44
6.4.2 Functional description . 45
6.4.3 Application layer gateway . 45
6.4.4 Gateway implemented by a router. 45
6.4.5 Gateway implemented by a bridge . 46
7 On-board data communication . 46
7.1 General . 46
7.2 Communication patterns . 46
7.2.1 Purpose . 46
7.2.2 Definitions . 47
7.2.3 Push pattern . 47
7.2.4 Pull pattern . 48
7.2.5 Subscription pattern. 50
7.3 Addressing . 50
7.3.1 General . 50
7.3.2 Network layer addressing . 50
7.3.3 Application layer addressing . 52
7.4 Availability of data communication . 53
7.5 Data classes . 53
7.5.1 General . 53
7.5.2 Service parameters . 53
7.5.3 TCN data class definition . 54
7.6 Communication profile . 55
7.7 Application profile . 56
8 Cybersecurity . 56
8.1 General . 56
8.2 System under consideration . 56
8.3 Lifecycle . 57
8.3.1 General . 57
8.3.2 Legacy systems . 57
8.3.3 Protocol design . 57
8.4 Guidelines . 57
Annex A (informative) High-level train architecture . 59
A.1 General . 59
A.2 Architectural realms . 59
A.3 On-board network structures . 61
IEC 61375-1:2026 © IEC 2026
Bibliography . 63
Figure 1 – Train backbone and consist network . 18
Figure 2 – Example of consist with 2 consist networks . 19
Figure 3 – End device connected to the train backbone (example) . 21
Figure 4 – Communication between train and ground (example) . 22
Figure 5 – Interfaces between consists . 23
Figure 6 – Train backbone bus topology . 24
Figure 7 – Train backbone switched topology (aggregated transmission media) . 24
Figure 8 – Train backbone switched topology (segregated transmission media) . 25
Figure 9 – Wireless train backbone mesh topology . 25
Figure 10 – Wireless train backbone base station topology . 26
Figure 11 – Wireless train backbone mesh topology for redundancy . 26
Figure 12 – Wireless train backbone base station topology for redundancy . 27
Figure 13 – Directions and orientation in a vehicle . 28
Figure 14 – Directions and orientations in a consist (example) . 29
Figure 15 – Directions and orientations in a closed train . 29
Figure 16 – Directions and orientations in train (TCN directions) . 30
Figure 17 – Structure of train directory (example) . 32
Figure 18 – Train inauguration block diagram . 36
Figure 19 – Train inauguration state chart . 37
Figure 20 – Independent orientation check with BEACON telegrams . 38
Figure 21 – Consist network standard interfaces . 40
Figure 22 – Consist network (bus technology) . 40
Figure 23 – Consist switches . 41
Figure 24 – Examples of consist network topologies (switched technology) . 42
Figure 25 – End device connected to two consist switches . 42
Figure 26 – Wireless consist network . 43
Figure 27 – Sub-networks in a consist network . 44
Figure 28 – Implementation example for two vehicle busses . 44
Figure 29 – Example of heterogeneous train control network architecture . 45
Figure 30 – Point to point communication pattern (push) . 47
Figure 31 – Point to multi-point communication pattern (push) . 48
Figure 32 – Point to point communication pattern (pull) . 49
Figure 33 – Point to multi-point communication pattern (pull) . 49
Figure 34 – Subscription communication pattern . 50
Figure A.1 – Example of architectural realm structure . 60
Figure A.2 – Examples for network segregation of on-board physical networks . 61
Table 1 – Train composition changes . 27
Table 2 – Train specific parameters (example) . 33
Table 3 – Consist specific parameters (example) . 33
Table 4 – Vehicle specific parameters (example) . 33
IEC 61375-1:2026 © IEC 2026
Table 5 – Device specific parameters (example) . 34
Table 6 – Point to point (Push). 48
Table 7 – Point to multi-point (Push) . 48
Table 8 – Point to point (Pull) . 49
Table 9 – Point to multi-point (Pull) . 50
Table 10 – Service parameters . 53
Table 11 – Principal data classes. 55
IEC 61375-1:2026 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Electronic railway equipment - Train communication network (TCN) -
Part 1: General architecture
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 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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 61375-1 has been prepared by IEC technical committee 9: Electrical equipment and
systems for railways. It is an International Standard.
This fourth edition cancels and replaces the third edition published in 2012. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Extension of train backbone topologies: aggregated and segregated topology;
b) Added independent consist orientation check with segregated train backbone topology;
c) Introduction of wireless technologies: wireless train backbone and wireless consist network;
d) Possibility of virtual networks;
e) Definition of data classes and protocol requirements suitable for the OMTS domain;
f) New clause about cybersecurity in train communication networks.
IEC 61375-1:2026 © IEC 2026
The text of this International Standard is based on the following documents:
Draft Report on voting
9/3252/FDIS 9/3293/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts of IEC 61375 series, under the general title Electronic railway equipment -
Train communication network (TCN), can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC 61375-1:2026 © IEC 2026
INTRODUCTION
IEC 61375-1 defines the general architecture of the Train Communication Network (TCN) to
achieve compatibility between consist networks and train backbones defined by the IEC 61375
series.
The creation of this fourth edition of the standard has been motivated by advances in
technology, namely in the fields of Ethernet communication, wireless communication, and
cybersecurity, which made it necessary to adapt or to extend some sections of the TCN general
architecture. These changes will then further on be reflected in the detailed technical
specifications given in subsequent parts of the IEC 61375 series.
The TCN has a hierarchical structure with two levels of networks, a train backbone and a consist
network:
a) for interconnecting vehicles in closed or open trains, this document specifies train
backbones with different characteristics.
b) for connecting standard on-board equipment, this document specifies consist networks with
different characteristics.
The general architecture of the TCN, which is defined in this document, does
c) establish the rules for interconnecting consist networks with train backbones, as
1) identifying the interfaces;
2) defining the principles of how train topology changes can be discovered;
3) defining the basic communication services provided by train backbones to be used by
consist networks;
d) establish basic rules for the train backbone and for the consist network;
e) establish rules for commonalities in operation, as:
1) patterns for the communication between users;
2) addressing principles;
3) data classes to be supported;
f) establish rules to support cybersecurity of the TCN.
IEC 61375-1:2026 © IEC 2026
1 Scope
This part of IEC 61375 applies to the architecture of data communication systems in open trains,
i.e. it covers the architecture of a communication system for the data communication between
vehicles of the said open trains, the data communication within the vehicles and the data
communication from train to the ground.
The applicability of this part of IEC 61375 to the train network technologies allows for
interoperability of individual vehicles within open trains in international traffic. The data
communication systems inside vehicles are given as recommended solutions to cope with the
said TCN. In any case, proof of compatibility between a proposed train backbone and a
proposed consist network will have to be brought by the supplier.
This part of IEC 61375 might be additionally applicable to closed trains and multiple unit trains
when so agreed between purchaser and supplier.
NOTE 1 For definitions of open trains, multiple unit trains and closed trains, see Clause 3.
NOTE 2 Road vehicles such as buses and trolley buses are not considered in this part of IEC 61375.
2 Normative references
There are no normative references in this document.
3 Terms, definitions, abbreviated terms, acronyms, and conventions
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org/
– ISO Online browsing platform: available at https://www.iso.org/obp
3.1.1
active train backbone node
train backbone node receiving a sequence number during train inauguration and forwarding
user data packets between consist network and train backbone
3.1.2
application layer
upper layer in the OSI model, interfacing directly to the application
[SOURCE: IEC 60050-811:2017, 811-37-03]
3.1.3
application process
element within a real open system which performs the information processing for a particular
application
[SOURCE: IEC 60050-811:2017, 811-37-05]
IEC 61375-1:2026 © IEC 2026
3.1.4
bridge
device which stores and forwards frames from one bus to
another on the base of their link layer addresses
[SOURCE: IEC 60050-811:2017, 811-37-09]
3.1.5
broadcast
nearly simultaneous transmission of the same information to several destinations
Note 1 to entry: Broadcast in the TCN is not considered reliable, i.e. some destinations can receive the information
and others not.
[SOURCE: IEC 60050-811:2017, 811-37-10]
3.1.6
bus
communication medium which broadcasts the same
information to all attached participants at nearly the same time, allowing all devices to obtain
the same sight of its state, at least for the purpose of arbitration
3.1.7
closed train
train composed of one or a set of consists, where the train composition does not change during
normal operation
EXAMPLE Metro, suburban train, or high-speed train unit.
Note 1 to entry: Consists are coupled in a workshop to establish a closed train for operation.
[SOURCE: IEC 60050-811:2017, 811-37-17]
3.1.8
communication device
device connected to the consist network or train backbone with the ability to transport, source
or sink data
[SOURCE: IEC 60050-811:2017, 811-37-18]
3.1.9
consist
single vehicle or a group of vehicles which are not separated during normal operation
Note 1 to entry: A consist can contain no, one or several consist networks.
[SOURCE: IEC 60050-811:2017, 811-37-20]
3.1.10
consist network
communication network interconnecting communication devices in one consist
Note 1 to entry: Consist networks do not spread beyond consist boundaries.
[SOURCE: IEC 60050-811:2017, 811-37-21]
3.1.11
consist network address
network address, which does not change after train inauguration and which is used to address
communication device in the own consist network
IEC 61375-1:2026 © IEC 2026
3.1.12
consist sequence number
sequence number of the consist in the train as obtained during train inauguration
3.1.13
consist switch
network component used in consist network based on switched technology
[SOURCE: IEC 60050-811:2017, 811-37-22]
3.1.14
cybersecurity
set of activities and measures taken with the objective to identify,
protect against, detect, respond to, and recover from unauthorized access or cyberattack which
could lead to an accident, an unsafe situation, or railway application performance degradation
[SOURCE: CLC/TS 50701:2023, 3.1.32]
3.1.15
end device
unit connected to one consist network or to one set of consist networks prepared for redundancy
reasons
[SOURCE: IEC 60050-811:2017, 811-37-33]
3.1.16
end node
node which terminates the train backbone
[SOURCE: IEC 60050-811:2017, 811-37-34]
3.1.17
essential function
function or capability that is required to maintain health, safety, the environment and availability
for the equipment under control
Note 1 to entry: Essential functions include, but are not limited to, the safety instrumented function (SIF), the control
function and the ability of the operator to view and manipulate the equipment under control. The loss of essential
functions is commonly termed loss of protection, loss of control and loss of view respectively. In some industries
additional functions such as history can be considered essential.
[SOURCE: IEC 62443-4-2:2019, 3.1.20]
3.1.18
function
application process which exchanges messages with
another application process
3.1.19
gateway
connection between different busses at the application
layer requiring application-dependent data analysis and protocol conversion
3.1.20
group address
address of a multicast group to which a device belongs
[SOURCE: IEC 60050-811:2017, 811-37-45]
IEC 61375-1:2026 © IEC 2026
3.1.21
integrity
property of a system to recognize and to reject wrong data
in case of malfunction of its parts
3.1.22
intermediate node
node which establishes continuity between two bus sections connected to it, but does not
terminate them
[SOURCE: IEC 60050-811:2017, 811-37-49]
3.1.23
linear topology
topology where the nodes are connected in series, with two nodes each connected to only one
other node and all others each connected to two other nodes (i.e. connected in the shape of a
line)
[SOURCE: IEC 60050-811:2017, 811-37-51]
3.1.24
local area network
part of a network characterized by a common medium
access and address space
[SOURCE: IEC 60050-811:2017, 811-37-60]
3.1.25
medium access control
sublayer of the link layer, which controls the access to the
medium (arbitration, mastership transfer, polling)
3.1.26
medium
physical carrier of the signal: electrical wires, optical fibers,
etc.
3.1.27
message
information which is transmitted in one or several packets from a
sender to one or more receivers
[SOURCE: IEC 60050-821:2017, 821-11-29]
3.1.28
multicast
transmission of the same message to a group of receivers, identified by their group address
Note 1 to entry: The term "multicast" is used even if the group includes all receivers.
[SOURCE: IEC 60050-811:2017, 811-37-66]
3.1.29
multimedia data
data used for onboard multimedia and telematic services (OMTS), like video/audio streams or
file transfer
IEC 61375-1:2026 © IEC 2026
3.1.30
multiple unit train
train comprising one or more train-units which can be controlled simultaneously from one cab
and able to operate at normal speed in either direction without re-marshalling
[SOURCE: IEC 60050-811:2017, 811-02-12]
3.1.31
network
set of possibly different communication systems which
interchange information in a commonly agreed way
[SOURCE: IEC 60050-811:2017, 811-37-68]
3.1.32
network address
address which identifies a communication device on network layer
[SOURCE: IEC 60050-811:2017, 811-37-69]
3.1.33
network device
component used to set up consist networks and train networks
Note 1 to entry: These components can be passive components like cables or connectors, active unmanaged
components like repeaters, media converters or (unmanaged) switches, or managed active components like
gateways, routers and (managed) switches.
[SOURCE: IEC 60050-811:2017, 811-37-70, modified – Note 1 to entry has been modified.]
3.1.34
network layer
layer in the OSI model responsible for routing between different busses
[SOURCE: IEC 60050-811:2017, 811-37-72]
3.1.35
network management
operations necessary to remotely configure, monitor,
diagnose and maintain the network
[SOURCE: IEC 60050-811:2017, 811-37-73]
3.1.36
octet
byte
ordered set of eight binary digits, operated on as an entity
[SOURCE: IEC 60050-171:2019, 171-02-12, modified – removal of Note to entry.]
3.1.37
open train
train composed of one or a set of consists, where the configuration can change during operation
EXAMPLE Locomotive-hauled international UIC (International Union of Railways, the international railways
operators association) trains.
[SOURCE: IEC 60050-811:2017, 811-37-79]
IEC 61375-1:2026 © IEC 2026
3.1.38
operator
enterprise or organization which is operating trains
3.1.39
operational data
data critical for train operation (TCMS), like propulsion control, brake control, doors control,
lighting control or heating, ventilation, and air conditioning control
3.1.40
packet
unit of a message (information, acknowledgement, or
control) transmitted by protocols on network or transport layer
3.1.41
realm
logical concept structuring train functions along coherent boundaries
3.1.42
receiver
electronic device which can receive signals from the
physical medium
3.1.43
repeater
< in a train communication network> connection at the physical layer between bus segments,
providing an extension of the bus beyond the limits permitted by passive means
Note 1 to entry: The connected segments operate at the same speed and with the same protocol. The delay
introduced by a repeater is in the order of one bit duration.
[SOURCE: IEC 60050-811:2017, 811-37-90]
3.1.44
ring topology
active network where each node is connected in series to two other nodes
Note 1 to entry: Ring can also be referred to as loop.
[SOURCE: IEC 60050-811:2017, 811-37-91]
3.1.45
router
connection between two busses at the network layer, which
forwards datagrams from one bus to another on the base of their network address
3.1.46
safety integrity
ability of a safety-related system to achieve its required safety functions under all the stated
conditions within a stated operational environment and within a stated duration
[SOURCE: IEC 60050-821:2017, 821-12-54]
3.1.47
service
capabilities and features of a sub-system (e.g. a
communication layer) provided to a user
[SOURCE: IEC 60050-811:2017, 811-37-93]
IEC 61375-1:2026 © IEC 2026
3.1.48
system under consideration
collection of assets that are needed to provide and operate
a railway application including any relevant network infrastructure assets
Note 1 to entry: In a cybersecurity context as defined in IEC 62443-3-2:2020, a system under consideration consists
of one or more zones and related conduits. All assets within a system under consideration belong to either a zone
or conduit.
3.1.49
switch
MAC bridge as defined in IEEE 802.1Q
Note 1 to entry: MAC means "Medium Access Control", a sub-layer within the Link Layer ruling which device is
entitled to send on the bus.
[SOURCE: IEC 60050-811:2017, 811-37-101]
3.1.50
topography
data structure describing the nodes attached to the train backbone, including their address,
orientation, position and node descriptor
[SOURCE: IEC 60050-811:2017, 811-37-105]
3.1.51
topology
possible cable interconnection and number of devices in a given network
[SOURCE: IEC 60050-811:2017, 811-37-106]
3.1.52
train
combination of rolling stock coupled together
Note 1 to entry: Rolling stock includes banking locomotives.
[SOURCE: IEC 60050-811:2017, 811-01-08]
3.1.53
train communication network
data communication network for connecting programmable electronic equipment on-board rail
vehicles
[SOURCE: IEC 60050-811:2017, 811-37-108]
3.1.54
train backbone
train bus
bus connecting the consists of a train, in particular the wire train bus, and which conforms to
the TCN protocols
[SOURCE: IEC 60050-811:2017, 811-37-107]
IEC 61375-1:2026 © IEC 2026
3.1.55
train backbone node
node
device on the train backbone that acts as a gateway
between the train backbone and the consist network
[SOURCE: IEC 60050-811:2017, 811-37-74, modified – "train backbone node" has been added
as preferred term.]
3.1.56
train backbone node number
node address
node number
unique number assigned to a node during train inauguration indicating the position of the train
backbone node on the train backbone
Note 1 to entry: This number can be used as part of the train network address for addressing devices in the consist,
the train backbone node belongs to, from any location in the train.
3.1.57
train composition
sequence, orientation and characteristics of consists which represent a train
3.1.58
train directory
data structure which describes the train composition and provides user information about the
consists
3.1.59
train inauguration
operation executed in case of tr
...