基于VxWorks的通信服务器实时多任务软件设计

为满足电力调度自动化系统对通信服务器高可靠性和强实时性的要求,提出基于嵌入式实时多任务操作系统VxWorks的通信服务器的软件方案。通信服务器的硬件基于嵌入式微处理器AT91RM9200芯片设计,软件主要实现通信规约转换和数据转发。软件系统结构采用双层客户机/服务器(C/S)结构,对下行通道,通信服务器是客户机,请求保护装置的数据,支持103规约;对上行通道,通信服务器是服务器,响应调度主站的数据请求,支持循环式数据传输规约(CDT)及101、104规约。其软件体系包括:系统初始化、系统配置、下行通道数据请求/处理、上行通道数据处理和数据库管理等模块。分析了数据流向及基于H.GEMMA原则的任务划分,确定了各任务的优先级,且任务可调用taskPrioritySet函数改变优先级。系统采用信号量和消息队列为通信机制,保证了系统的实时性,并给出了通信服务器主程序流程图。

Real-time multitask software design of communication server based on VxWorks

A software design of communication server based on embedded RTOS(Real-Time Operating System) VxWorks is proposed to satisfy requirements of electric power dispatch automation system for high reliability and real-time performance.The hardware is designed based on embedded microprocessor AT91RM 9200,and the software realizes protocol conversion and data transfer.The software system adopts double-layer client / server structure.To downstream channels,the communication server acts as a client,requesting data of protection units and supporting protocol IEC-60870-103.To upstream channel,the communication server acts as a server,responding the data request of dispatch master station and supporting protocol CDT(Cyclic Digital Transmission),IEC-60870-101 and IEC-60870-104.The software architecture consists of models of system initialization,system configuration,data request and processing of downstream channels,data processing of upstream channel and database management.The data stream and the multitask division of communication server based on H.GEMMA rule are analyzed.Task priority is determined and it can be changed by calling taskPrioritySet function.The communication server uses semaphore and message queue as communication modes to guarantee the real-time performance of system.The main program flow of communication server is given.