Industrial networking for rail is the wired communication infrastructure inside rolling stock that connects onboard subsystems, supports train control and management, and carries operational data to ground systems.
The wired network inside the train complements the radio side of railway connectivity and communications: every subsystem that reports to ground over GSM-R or FRMCS first travels the train’s internal network.
Its foundation has been standardised since 1999 and is now shifting from serial fieldbuses to Ethernet.
The Train Communication Network
The Train Communication Network (TCN), standardised under IEC 61375, defines two serial bus layers. The Multifunction Vehicle Bus (MVB), standardised in IEC 61375-3-1, interconnects electronic equipment within a single vehicle — traction electronics, brakes, doors, heating, ventilation and air conditioning (HVAC), passenger information, event recorders, and cab displays.
The Wire Train Bus (WTB), standardised in IEC 61375-2-1, connects vehicles across the train using twisted shielded-wire pairs spanning up to 860 metres.
The TCN was adopted as IEC 61375 in 1999 — the same year the IEEE Rail Transit Vehicle Interface Standards Committee adopted a TCN-based variant as IEEE Std 1473-1999. Manufacturers including Siemens, ABB, and Bombardier (now Alstom) adopted it, and it remains in service on a large portion of the European fleet.
Ethernet-based successors
The shift from serial fieldbuses to Ethernet inside rolling stock is formalised in IEC 61375-2-5, which defines the Ethernet Train Backbone (ETB) replacing the WTB at the train-wide layer, and IEC 61375-3-4, which defines the Ethernet Consist Network (ECN) replacing the MVB within each vehicle.
These standards specify 100 Mbit/s switched Ethernet for the real-time process data exchange that MVB previously handled. The Train Real-Time Data Protocol (TRDP), standardised in IEC 61375-2-3 with an open reference implementation under TCNOpen, provides this exchange; IPTCom, its proprietary Bombardier-originated predecessor, remains in service on older fleets.
Ethernet improves bandwidth and reduces hardware cost, but standard Ethernet lacks deterministic real-time guarantees, which has limited adoption for the most safety-critical control functions. Time-Sensitive Networking (TSN) extensions under IEEE 802.1 provide bounded latency and deterministic delivery, and are entering evaluation for railway applications where they would allow safety-critical and non-safety data flows to share a single Ethernet fabric.
Safety-critical communication requirements
Onboard traffic that carries train protection commands, door interlock signals, and brake commands must satisfy EN 50159, which specifies the threats to guard against and the corresponding defences for safety-related communication over open transmission systems.
Where TCN or Ethernet carries such traffic, the application layer must implement the coding and error detection mechanisms specified in EN 50159, independently of the underlying physical transport.
The Train Control and Management System (TCMS) coordinates all onboard subsystems through the TCN or ETB/ECN network. Modern TCMS implementations also provide the gateway through which condition monitoring data, event logs, and diagnostic information reach ground systems over the GSM-R or FRMCS radio link for remote maintenance access.