WTB Research And Realization Of Train - Bus Network

The Train Communication Network (TCN) integrates all devices of the vehicles into a unit. Via TCN, the motorman can send instructions to any vehicle and control the whole train easily;and various vehicles status can be sent back to the monitor of the motorman. TCN helps the motorman to control the train more efficiently and more safely. Furthermore, TCN can support the train intellectualization, and networkizing, including train reconfiguration.In July 1999, IEEE committee approved IEC61375-1 as the TCN standard, and published IEEE Std 1473-1999 communication protocol standard for vehicles, including both TCN and LONWORKS. This standard is recommended in China, and defined as follows. The "communication network of train" is composed of Wristed Twisted Bus(WTB) and Multi-Variable Bus(MVB), in which WTB is used to connect all vehicles to be a auto-configuration network of the train, and MVB is used inner each vehicle to connect various electric devices of the vehicle. This thesis only studies the WTB network.Having digested standard IEC61375-1, we found that WTB network adaptor is the key component of WTB, so we treat it as the most important object. Its functions, composition and technical requirements are thouroughly studied. A detailed design has been completed. The types and formats of communication instructions and data frames are designed according to the Real Time Protocol. There are 2 kinds of communication: "cyclic, source-addressed broadcast of Process Data", and "sporadic, connectionless transmission of Message". Transmission uses Manchester encoding. There are 3 channels, 2 for WTB and 1 for MVB, each with dual-redundent construction. According to the technical requirements, the embedded PC/104 with mini-size and wide temperature range is selected as node processor. A FPGA chip (Altera Cyclone C6, with 5980 Logic elements) is selected as kernel device of the adaptor. Whole logic circuits are integrated in a single chip, just like a SOC (System On a Chip). We have succeeded to build a prototype adaptor.To design this chip, an advanced Quartus II 4.0 EDA Tool is used . and many key technologies and methods are resolved, including "trafic store" and "index memory" optimized design, distributed data-base, Manchester encoding and decoding, framegeneration, various FSMs for different frames, etc.