基于μC/OS-Ⅱ的Modbus/TCP消息的类令牌环实时响应算法

A token-ring-like real-time response algorithm of Modbus/TCP message based onμC/OS-Ⅱ

Modbus/TCP工业以太网标准本身不保证实时性。设计一种带优先级的令牌环调度算法,实现了对高优先级Modbus/TCP消息的实时响应,并在该算法基础上扩展出加权令牌环调度算法和变权令牌环调度算法,能满足可定制、可更改的响应延时需求。最后,在基于μC/OS-II+ARM7的平台上测试响应延时为1.15±0.15ms,优于目前大多数对Modbus/TCP的实时性改造成果,甚至达到了开放模式下Powerlink的实时水准。

Modbus/TCP industrial Ethernet standard cannot guarantee the real-time capability by itself. A token ring scheduling algorithm is designed, which uses priority to achieve the real-time response to high-priority Modbus/TCP messages. Based on that, a weighted token ring scheduling algorithm and a weight-variable token ring scheduling algorithm are developed to meet the customizable and changeable time delay demands. Finally, the response delay on μC/OS-Ⅱ-ARM7 platform is measured to be 1.15 ±0.15ms, which is superior to most current researches that aim at improving the real-time capability of Modbus/TCP, and what＇s more, it reaches the level of POWERLINK working in open mode.