摘要
FF现场总线采用集中令牌式通信介质访问控制方式 .首先 ,本文针对单调速率算法没有考虑周期相同时任务的调度 ,提出了扩展单调速率算法 ,以便对周期信息进行优先级分配 ;其次 ,应用此算法 ,给出构建调度时间表的方法 ,并给出了简易的调度时间表有效性判据 ,以保证周期信息的实时性通信 ;最后 ,通过一个应用实例来描述扩展单调速率算法及在
The Fieldbus Foundation protocol is based on a centralized communication media access control mechanism, where a link active scheduler controls all messages transfer between different field devices on a bus according to a schedule time list pre defined. Firstly, since the rate monotonic algorithm did not consider the schedule for the tasks whose periods are same, the paper provides the algorithm of extended rate monotonic to assign the priority level for all communicating periodic messages. Secondly, the approach how to build a schedule time list based on the extended rate monotonic arithmetic is proposed, and the condition judging the validity of the schedule time list built is given by analyzing the maximum waiting time, in order to guarantee the real time communication of the periodic messages. Finally, the extend rate monotonic algorithm and its application in building the FF schedule time list are showed by a example of application.
出处
《信息与控制》
CSCD
北大核心
2001年第5期418-421,共4页
Information and Control
基金
国家自然科学基金 ( 6 0 0 840 0 1)
