Research And Realization Of Field Bus Communication In All-electronic Computer Interlocking System

The current computer interlock system take relay circuit as the interface,and completely retain the rail-side device driver circuit implemented by relay logic such as turnout drive,signal lighting,etc.All-electronic computer interlock system achieves technological progress,and use the electronic execution unit rather than the relay circuit to control the equipment next to rail.It is an electronic,intelligent and advanced new generation of computer interlocking system.The intelligent implementation of the system will increase the control level of the system,increase the information transmission time within the system and the "false reservation" risk.And thus the system real-time,reliability and security of the internal communication have higher requirements.This paper first introduces the structure and characteristics of the all-electronic computer interlocking system,and combines the characteristics of the system to study its communication technology foundation to achieve a variety of field bus technology to meet the safety,reliability,real-time,deterministic communication requirements of the full electronic interlocking.In the aspect of real-time research,an improved EDF scheduling algorithm is designed.The algorithm uses the concept of exponential partition to divide the relative deadline,and dynamically assigns the priority to the message according to the network condition.This paper not only establishes the model of improved EDF algorithm,but also analyzes its schedulability and quantization error deeply,and proves its optimism in theory.Then,the monitoring module of the all-electronic execution unit is taken as the research object,and its function,design and software realization are introduced in detail.The coding of the arbitration domain is modified according to the improved EDF algorithm.It makes the module complete analog acquisition,processing and transmission of work.Finally,the Truetime simulation toolbox is chose as the experimental tool.The comparison between the RM algorithm and the EDF algorithm is carried out,and the data of the monitoring module is used to prove the usability and optimality of the EDF algorithm.Experiments show that compared with the traditional scheduling algorithm,the improved EDF scheduling algorithm can dynamically schedule according to the situation of the network,and the flexibility is higher.In the case of heavy network load,it can better meet the real-time communication demand.