The Research And Design Of Multifunction Vechile Bus Control System Based On DSP

With the development of the technology of embedded microcontrol and field bus, the process control of modern train has developed from concentrated direct digital control system to distributed control system which based on network.IEC-61375-Train Communication Network(TCN) Standard is IEC association with UIC adopted a standard for standardizing the communication of device data on train,TCN is divided into train level communication network—WTB which is used for connecting each dynamically organized vehicle and vehicle level communication network - MVB which is used for connecting fixed devices in vehicle. MVB which based on contributed control is part of IEC61375-1(1999)TCN, together with WTB has strong time-critical characteristic and high reliability.MVBC(Multifunction Vehicle Bus Controler) is the only core part in MVB devices. The technology of its production is monopolized by foreign manufacturers, therefore research and application of MVB is limited by much factor,such as technology blockage. For researching and applying MVB,developing MVBC is the first task by ourselves. Therefore ,the paper focus on the the technology of MVB of TCN , analyzes and compares the differences between MVB and other kind of field bus. A control system which based on "DSP+CPLD Architecture" is designed according to MVB standard. The main part of this scheme includes a microcontroller for the link and network layers, a CPLD for the implementation of Encoder/Decoder of the physical layer, to perform a slave node in a MVB communication.MVB is higher advantage and latency time of MVB is lower than those of CSMA/CD (Carrier Sense Multiple Acess) 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 can operate in harsh and disturbed environments, for example inside railway vehicles of the train communication network.The paper give the whole system fuction module diagram and ciucuit principle picture in detail,and the code of interior function module which based on Verilog HDL. The simulation result which uses MAXPLUSII is given and analysed.