The Mvb Bus Management Functions Of Four Types Of Equipment Key Technology Research And Implementation

TCN (Train Communication Network) is the most widely adopted train communication standards, which can be divided into WTB (Wired Train Bus) and MVB (Mutifunction Vehicle Bus) by function. As MVB Class 4 devices that have bus management function are the core of the MVB technology, in order to develop MVB productions with independent intellectual property, it is pivotal to research on key technologies of such devices.Based on in-depth analysis of MVB protocol and structure of the MVB Class 4 devices, this dissertation points out that it is a key technology on the development of the MVB productions that how to realize bus controller of the MVB Classe 4 devices and solve problem of real-time scheduling for task moduls in the protocol stack. Accroding to the functions, the bus controller is devided into four modules: traffic memory control module, main control unit, coding and encoding unit. By adoping a top-down module design method, the control function of the MVB Class 4 is realized in FPGA.In the MVB, communication is real-time. What's more, the tasks between periodic phase and sporadic phase have different features, so a single kind of task scheduling algorithm can not satisfy their demands. Therefore, a double select task scheduling algorithm is designed, in which the upper layer selects the scheduling algorithm based on the current phases, while the lower layer selects task based on the scheduling algorithm. Accordingly, the problem of real-time scheduling is solved by the proposed algorithm. In addition, the protocol stack of the MVB Class 4 devices is proposed. Under the Linux platform, firstly the functions of transimiting variables and bus managing are realized by programming with C Language. Secondly, in a way of memory mirror in link layer, the bottom interface is achieved by accessing the shared memory. In application layer, according to different applications, the functions of accessing a single variable, a set of variables and all the variables are realized respectively. Then, the link medium assignment is achieved by adopting a timer, while the function of event arbitration is implemented through preorder traversal event arbitration of binary tree.Finally, a test platform is developed for the MVB devices, which consists of four normal MVB test devices, a MVB Bus_Administrator, a MVB protocol analyzer and the devices that need to be tested. By analyzing the devices with the MVB protocol analyzer, the results indicate that the functions of the Class 4 devices are well compatible with standard devices and accord with the IEC61375 standard.