CLC/TR 50542-3:2026

• Abstract:

  The scope of this document is the definition of the functional interface between the TDC and other train systems. These "Other Train Systems" are the train systems interfacing with the TDC excluding the displays (CLC/TR 50542-2), ETCS/STM onboard (Subset-121) and already designed class B ATP systems. The functional interface deals with data exchanged between the TDC and these train systems as shown in Figure 1. The TDC is defined in document CLC/TR 50542-1. (...)

• Status: Published
• Publication Date: 04-Jun-2026
• ICS: 35.240.60 - IT applications in transport
• ICS: 45.020 - Railway engineering in general
• Technical Committee: CLC/TC 9X - Electrical and electronic applications for railways
• Drafting Committee: CLC/TC 9X/WG 12 - Communication means between safety equipment and man machine interface (mmi)
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 05-Jun-2026
• Due Date: 17-Jul-2026
• Completion Date: 05-Jun-2026
• Ref Project: SIST-TP CLC/TR 50542-3:2026 - Railway applications - Driver's cab Train Display Controller (TDC) - Part 3: Other Train Systems FIS

• Replaces: CLC/TR 50542-3:2016 - Railway applications - Driver's cab train Display Controller (TDC) - Part 3: Other train systems FIS
• Effective Date: 10-Dec-2024

Overview

CLC/TR 50542-3:2026 is a technical report developed by CLC (European Committee for Electrotechnical Standardization) focusing on railway applications-specifically, the functional interface between the Train Display Controller (TDC) in the driver’s cab and "Other Train Systems" (OTS). This document details how the TDC communicates with other critical onboard systems, excluding display systems, ETCS/STM onboard modules, and class B ATP systems, as defined in associated standards.

The primary aim of this technical report is to define clear and interoperable functional interfaces for efficient integration, streamlined maintenance, and reduced life-cycle costs of rolling stock electronic systems. By establishing common principles and functions, the standard supports innovation and compatibility in both new and refurbished trains.

Key Topics

• Functional Interface Specification (FIS)
  Defines the nature and structure of data exchanged between the TDC and other train systems.

• Information Flow
  Categorizes information as "input" (from OTS to TDC), "output" (from TDC to OTS), or bidirectional.

• Standardized Functions

  • State Information: OTS updates TDC on system status (e.g., brakes applied).
  • Commands: TDC sends operational requests to OTS (e.g., door control).
  • Provide Video: Supports video data transfer, such as from onboard CCTV systems, to the TDC.
  • Management Functions: Includes status monitoring and reporting for effective system oversight.

• Clear Separation
  The interface specification is designed to be independent from physical devices, focusing on optimizing system functionalities.

• Practical Examples
  Annex A provides relevant use cases to illustrate the implementation of OTS functions (e.g., passenger alarm, hot box detection, door operations).

Applications

CLC/TR 50542-3:2026 brings significant value to a range of stakeholders in the railway industry:

• Rolling Stock Manufacturers
  Achieve better modularity and supplier flexibility when designing or refurbishing train cabs.

• System Integrators
  Facilitate seamless integration of new onboard subsystems with existing TDC infrastructure, ensuring rapid upgrade cycles and compatibility.

• Maintenance and Operations Teams
  Simplify processes for component replacement, troubleshooting, and long-term fleet management thanks to the well-defined functional interface.

• Safety and Monitoring
  The standard’s approach supports the incorporation of safety-relevant information (like passenger alarms and onboard detection), enabling safer and smarter train operation.

• Innovation Enablement
  Establishes a neutral platform for future expansion, supporting the integration of emerging technologies such as enhanced data-driven maintenance, advanced video analytics, or modern HVAC interfaces.

Related Standards

For comprehensive implementation and system consistency, refer to these related documents:

• CLC/TR 50542-1: Railway applications – Driver's cab Train Display Controller (TDC) – Part 1: General architecture
  Describes the overall system architecture and primary attributes of the TDC.

• CLC/TR 50542-2: Railway applications – Driver's cab Train Display Controller (TDC) – Part 2: Display systems FIS
  Focuses specifically on the interface between TDC and train display modules.

• Subset 121 (DMI-EVC interface):
  Addresses interfaces with the European Train Control System (ETCS) and on-board Specific Transmission Modules (STM).

By aligning with these standards, railway stakeholders ensure interoperability, reduce life-cycle costs, and enable ongoing modernization of train control and information systems across Europe.

Keywords: railway applications, Train Display Controller, TDC, functional interface, onboard systems, maintenance, train integration, passenger safety, CLC standards, rolling stock interoperability.

SLOVENSKI STANDARD
01-oktober-2026
Nadomešča:
SIST-TP CLC/TR 50542-3:2017
Železniške naprave - Krmilnik vlakovnega prikazovalnika (TDC) v strojevodskem
prostoru - 3. del: Drugi vlakovni sistemi (FIS)
Railway applications - Driver's cab Train Display Controller (TDC) - Part 3: Other Train
Systems FIS
Bahnanwendungen - Display-Steuereinheit (TDC) für Führerräume - Teil 3: Andere
Zugsysteme FIS
Applications ferroviaires - Contrôleur d'écrans de cabine (TDC) - FIS pour autres
systèmes de train
Ta slovenski standard je istoveten z: CLC/TR 50542-3:2026
ICS:
35.240.60 Uporabniške rešitve IT v IT applications in transport
prometu
45.020 Železniška tehnika na Railway engineering in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT CLC/TR 50542-3

RAPPORT TECHNIQUE
TECHNISCHER REPORT June 2026
ICS 35.240.60; 45.020 Supersedes CLC/TR 50542-3:2016
English Version
Railway applications - Driver's cab Train Display Controller
(TDC) - Part 3: Other Train Systems FIS
Applications ferroviaires - Contrôleur d'écrans de cabine Bahnanwendungen - Display-Steuereinheit für Führerräume
(TDC) - FIS pour autres systèmes de train (TDC) - Teil 3: Andere Zugsysteme FIS

This Technical Report was approved by CENELEC on 2026-05-18.

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. CLC/TR 50542-3:2026 E

Contents Page
European foreword .3
Introduction .4
1 Scope .5
2 Normative references .5
3 Terms and definitions .5
4 Symbols and abbreviations .6
5 General principles.6
6 Functions .7
6.1 General .7
6.2 State .7
6.3 Command .7
6.4 Provide Video .8
6.5 Management functions .8
6.5.1 TDS Status .8
6.5.2 OTS Status .8
6.6 Relationship between CLC/TR 50542-2:2025 and this document .8
Annex A (informative) Examples of OTS functions . 10
Bibliography . 11
European foreword
This document (CLC/TR 50542-3:2026) has been prepared by CLC/TC 9X “Electrical and electronic
applications for railways”.
This document supersedes CLC/TR 50542-3:2016.
3:2016:
— Clause 2: the normative references have been deleted.
— Note 1 added to term entry 3.2.
— Note 1 added to term entry 3.3.
— Clause 4: TDS added.
— Clause 5: addition of a reference to Annex A.
— 5.1: direction is clearly described from the OTS and TDC point of view.
— 5.2: clarification added about the use of the function.
— 5.3: a note has been added to clarify the source of the request.
— Annex A:
— application to CCTV has been clarified,
— OTS Onboard hot box detecting system added, as an example of safety related OTS.
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.
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.
Introduction
The extent of CLC/TR 50542-3 is the functional interface between the Other Train Systems (OTS) and the TDC.
The functional definition of this interface is a key feature in the process to increase market development, for
instance:
— by introducing more suppliers for new rolling stock development and for driver's cab refurbishment;
— by easing the control of maintenance and the replacement processes;
— by decreasing the related equipment Life cycle cost.
In this document, the train borne systems and the TDC are considered only regarding their functionalities and
not as physical devices.
The CLC/TR 50542 series consists of three documents:
— CLC/TR 50542-1, Railway applications — Driver's cab Train Display Controller (TDC) — Part 1: General
architecture;
— CLC/TR 50542-2, Railway applications — Driver's cab Train Display Controller (TDC) — Part 2: Display
systems FIS;
— CLC/TR 50542-3, Railway applications — Driver's cab Train Display Controller (TDC) — Part 3: Other train
systems FIS (this document).
This series of documents is not a standard but the result of a study on the future view of the system. They do
not describe an existing solution for the TDS.
These documents are not written to be used in call for tenders because they are not sufficient. However, they
can serve as a basis for future development and standardization including new technologies. These documents
are a first step and may be completed later.
NOTE In case of existing discrepancies between CLC/TR 50542-1:2025 and CLC/TR 50542-3:2026, the present
document prevails.
1 Scope
The scope of this document is the definition of the functional interface between the TDC and other train systems.
These “Other Train Systems” are the train systems interfacing with the TDC excluding the displays
(CLC/TR 50542-2), ETCS/STM onboard (Subset-121) and already designed class B ATP systems.
The functional interface deals with data exchanged between the TDC and these train systems as shown in
Figure 1.
The TDC is defined in document CLC/TR 50542-1.
...