Design And Implementation Of The Switching Unit In Double2-vote-2Safety Computer Platform

With the development of computer technology,the computer sysetems are playing more and more important role in society,and are widely used in rail transit, aerospace,nuclear power station,industrial control and other safety-critical areas.Safety computer as an important part of safety-critical system,safety and reliability are vital importance. Because of the marketable and compatibility of computer products,the researchers prefer safety computer platform built by commercial off-the-shelf to expensive dedicated computer.The requirement of safety computer platform is analyzed. Through comparing various platform structures, double2-vote-2structure is selected as the hardware structure of the platform.The new design scheme of platform is raised,and MPC5643L is selected as the system processor. The processor internal structure, main feature and functional safety concepts are analyzed in detail.The functional designs of the safety computer platform are described, include synchronization and comparison in the subsystem,communication and synchronization between subsystems,fault collection and control. Moreover,they are introduced in detail.Switching unit improves the reliability of the safety computer platform effectively,and is designed by two different methods. Switching unit based on software and hardware combined,is made up of hardware circuit and software and has the characteristic of interlocking. Switching unit based on communication, is dependent on communication between two subsystems.Communication interface circuit is designed to improving independence and generality of the platform,and is implemented based on Field Programmable Gata Array. In software,switching logics are designed according to the relative,include basic principles,how to decide to the host and how to switch.Finally, the safety computer platform is built up. Testing scheme and codes are given. From the part to the whole,the system is debugged and tested.The different switch units are introduced in the paper,and have been applied in several railway signaling systems. The application results show that the schemes are practical and applicable to the work, meet the needs of high reliability and can be used for reference.