Tritem Train Realtime Data Protocol (TRDP) Custom Device
TRDP (Train Real-time Data Protocol) is an Ethernet-based protocol used in Train Communication Networks (TCNs) for the real-time exchange of data between onboard subsystems. It operates primarily over UDP for cyclic Process Data (PD) and over TCP/UDP for acyclic Message Data (MD). The protocol supports multicast communication and is designed to ensure low latency, bounded jitter, and high reliability in safety-critical environments. It is commonly used for functions such as diagnostics, vehicle control coordination, and passenger information systems.
The TRDP CD allows access to the TRDP communication network for reading and writing data. Each CD instance simulates a single device. To simulate multiple units, all required IP addresses must first be configured on the available network interface.
The custom device support following communication patterns:
TRDP Process Data protocol via UDP:
- cyclic PD Data (point to point, point to multipoint, multipoint to point)
TRDP Message Data protocol via UDP (point to point, point to multipoint, multipoint to point):
- MN – Message Data notification (sender, receiver)
- MR – Message Data request with reply (sender, receiver)
- MP – Message Data reply without confirmation (sender, receiver)
Configuration
The TRDP CD provides options for specifying the path to an XML configuration file. Once the configuration has been loaded, the CD displays the detected device name and IP address.
Channels are divided into two groups: Inputs (transmitted data) and Outputs (received data). These groups contain all assigned ComIDs from the configuration file, together with diagnostic channels.
The TRDP CD accepts XML configuration files as described in IEC 61375-2-3, Annex C: Train Real-Time Data Protocol Configuration.
Diagnostic Channels
TRDP CD creates several diagnostic channels.
| Channel | Description |
|---|---|
| Deactivate_index | When set, the device is deactivated and no data is sent or received. |
| SendID (outgoing MD only) | Trigger used to send an MD message. The value must differ from the previous value. |
| ReqComID (message data request/reply only) | Specifies comID for request/reply scenarios. Sending triggered via _SendID channel. |
| ErrorCounter (incoming comIDs only) | Number of errors detected in the frame checksum, Session ID, and UUID. Counter increments for each invalid frame received. |
| SeqCounter (incoming comIDs only) | Counter of incoming frames. Incremented for each received frame. |
| SeqNumber (incoming comIDs only) | Message sequence number received within a TRDP frame. |
| MC_FilterEnable (incoming comIDs from a multicast group only) | Enables multicast source IP filtering. Only frames from the IP address defined in the _MC_Address channel are accepted. |
| MC_Address (incoming comIDs from multicast group only) | Source IP address of the device used for multicast filtering. Stored as a U32 value. |
License
The TRDP CD requires a valid license to operate.
To obtain a license, please submit a license request. License acquisition and allocation are managed through the internal licensing process. The responsible team will provide further instructions and guide you through the necessary steps upon receipt of your request.