一种新型实时总线协议及其FPGA设计

对于小规模总线型测控系统,目前国内还没有形成一个完整的通讯规范,因此建立一种完善的实时总线体系结构及其通讯标准就成为一个重要的研究课题;考虑到数据链路层协议对网络的实时特性有重要影响,借鉴工业现场总线Profibus和802.4协议,提出了一种适合小型化控制系统的新型令牌总线模型;详细阐述了这种总线模型数据链路层协议的令牌环生成和维护方式、令牌传递方式以及数据收发方式,介绍了基于FPGA技术实现该协议的具体方法,给出了信息传输时间的理论最大值和实际测试结果;实验结果表明这种低成本、小规模测控网满足了系统实时性要求,达到了预期效果,具有一定的实用性和推广价值。

A New Type of Real-time Control Bus Protocol and Its FPGA Design

As to bus type small-scale observation and control system,a perfect communication specification have not been formed in our country at present,so setting up a kind of complete real-time bus system structure and communication standard becomes an important research subject.Considering data link layer protocol has important influence on its real-time characteristic,taking industry field bus Profibus and 802.4 protocol as reference,a new type of token bus model suitable for small-scale observation and control system is presented.The way of token-ring production and maintenance,token passing,data receiving and sending of this new type of token-bus data link protocol are illustrated in detail.Its concrete implementation based on FPGA technology is introduced,theory maximum of information transmission time and real test results are given.The experimental result shows the low cost,small-scale network of observation and control can satisfy the real-time character request,and it comes to the expectant result and has certain value to popularize.