Research & Realization On A Highly Robust Real-time Communication Fieldbus

The Multifunction Vehicle Bus(MVB), together with the Wire Train Bus(WTB) are part of the Train Communication Network(TCN),which is developed of the International Standard of TEC 61375-1. The MVB is a highly robust real-time field bus specifically designed for control systems built into railroad vehicles, and has become an international standard fieldbus in modern train communication network. It provides both the interconnection of programmable equipment amongst themselves and the interconnection of this equipment with its sensors and actors. Due to the fact that the MVB protocol is not specialized to specific transportation application, it is also very well suited in industrial application as a universal field bus where strict safety and reliability requirements are needed.This paper firstly gives a brief introduction on the TCN,the Real-Time Protocol, then focus on the MVB, gives a research of the MVB in detail, especially the physical and link layers. Meanwhile, MVB is analysed in theory ,and its polling mode is compared with CSMA/CD MAC mode, which are extensively used in IEEE802.3 and the Ethernet. Under normalizing condition, the throughput of MVB is higher and latency time of MVB is lower than those of CSMA/CD during transmitting process data. Although the performance of CSMA/CD is better during transmitting message data, with respect to the extra spend caused by the limitation of minimum data field size in MAC frame and the jam signal when collision, and the selected back-off algorithm which can not assure a high reliability and real time communication, MVB is a deterministic and robust field bus more suitable for safety-sensitive systems which must operate in harsh and disturbed environments, for example inside railway vehicles of the train communication network.An integrated design scheme is also presented in this thesis, which is based on "MCU+CPLD/FPGA Architecture", to realize the function of Multifunction Vehicle Bus Controller(MVBC).The main part of this scheme includes a microcontroller for the link and network layers, a PLD for the implementation of Encoder/Decoder of the physical layer, to perform a slave node in a MVB communication. The emphasis of the design is the function realization in CPLD, the detailed logic circuit of CPLD and its VHDL program, and also the extended work for future are given.