TCN – From Train Bus to Vehicle Bus
The TCN Train Communication Network, integrated into the IEC 61375 standard, was developed together with UIC and describes time and safety critical data transmission in railway vehicles. Their goal is worldwide inter-
operability of different trains and equipment via Plug and Play. The TCN architecture com-
prises a train bus and a vehicle bus. The Wire Train Bus (WTB) operates at 1 Mbit/s over a distance of 860 m on twisted wire pairs. The WTB provides unique features such as auto-numbering of vehicles and cleaning action of the coupler‘s contacts.The Multifunction Vehicle Bus (MVB) operates at 1.5 Mbits/s over optical fi bers and/or twisted wire pairs.The TCN busses provide two main trans-mission services: deterministic transmission of time-critical process data through perio-
dical source-addressed broadcast and on-
demand reliable transmission of messages through either a point-to-point or a multi-
cast transport protocol. The TCN offers a full 7-layer architecture and routes message packets based on logical addresses. Network management services support commission-
ing and maintenance.
MVB Interface on PCI-104 Module PP4 Custom WTB Interface
This custom PC/104- Plus module is a fully EN 50155 compliant WTB transmitter and receiver interface for locomotive control. It provides two independent channels with red-
undancy function. The WTB communication controller is realized as an IP core in the on-
board FPGA. The WTB lines are accessible on two D-Sub
industrial connectors at the front panel. The transceivers are electrically isolated from the line by a transformer. The signaling data rate is 1 Mbit/s. The transmitter is a differential dri-
ver capable of sourcing a short circuit current of 1A. Each transmitter provides a transmit enable line and a feedback signal to the FPGA to detect a shorted line.A unique feature in train networks is “fritting“. To overcome contact oxidation in relays and connectors, a node may apply a very high DC voltage between the wires X and Y of either direction. The fritting source on this module supplies a direct voltage of 48V -10/+20 % measured at the connection points.Together with the standard PCI-104 CPU board PP1 (PowerPC The PP4 is an optically isolated MVB transmit-ter and receiver interface with EMD (Electrical Middle Distance medium) physical interface. Versions with ESD (Electrical Short Distan-
ce medium) and OGF (Optical Glass Fiber me dium) are available on request.The PP4 provides master and slave functio-nality and has one redundant MVB channel (double line attachment confi guration) accessible via two 9-pin D-Sub connectors. It is based on the Siemens ASIC MVBCS1 and on an on-board FPGA. The functional device classes 1, 2, 3 and 4 of the MVB can be confi -gured. The isolation voltage is 1500 V DC and 1000 V AC. The PP4 is fully compliant with EN 50155.
32-bit/33-MHz PCI target MVB transmitter/receiver Master and slave interface 1 redundant channel Isolated EMD (optionally ESD and OGF) Up to 16 MB SDRAM, 2 MB Flash
® MPC5200) it realizes a
industrial gateway from WTB to CAN bus.
32-bit/33-MHz PCI target WTB function in FPGA 2 independent transmitter/receiver
channels
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