The Design And Realization Of The Link Layer Of The WTB Node

WTB is short for Wire Train Bus. It is a part of the IEC61375-1 electric railway equipment-train bus international standard, which was published by IEC in 1999. China, and most of the world's biggest train manufacturers and operators participated in this standardization work. It is primary designed for railway vehicle and widly used in long-distance trains, high speed trains and subway trains.WTB has already been equipped in some of the high speed long distance trains and subway trains, but in general, most of these equipments are bought from foreign companies. Such devices developed by ourselves and can be applied to practical use are still a blank.This paper studied the WTB part of the IEC61375-1, and mainly focused on the design and realization of the link layer with SAB82525 and AM7960. Two samples were made to do a communication test under the control of the AVR Mega128 microcontroller, and the results proved that the MAU hardware could meet the standard's basic connection requirement. Another job of this paper is to construct a simulation platform for the test of the WTB software. This platform is composed by Microsoft Virtual PC and the Virtual Serial Ports Driver. The Virtual PC plays as WTB nodes, and the Virtual Serial Ports Driver provides RS232 communication function to simulate the data transmission in a real WTB wire. Finally, an inauguration software were developed on this platform using uC/OS-II to meet the real-time requirement and the C language to reduce the cost of porting. According the test, this program could execute inauguration function successfully on the simulation platform.. This result also proves that the platform can act as a real WTB bus.