Ning Liu, Chongquan Zhong, and Tonglong Xue
Ethernet for plant automation (EPA), function blocks, executionscheduling, cycles synchronization
In the system based on EPA (Ethernet for plant automation) In- dustrial Ethernet, the invalid execution of function blocks (FBs) is an important problem that restricts the real-time performance of system. Based on EPA deterministic communication scheduling mechanism, a method called EPA function blocks execution schedul- ing was proposed in this article. The method integrates all the FBs in a single-field device into a function task and sets the function time slice for the execution of the function task according to the principle of the cycle synchronization between the execution of FBs and the data communication in EPA system. On this basis, the method first realizes the single execution of each device’s function task in an EPA communication macrocycle by setting a scheduling tag in each FB and then realizes the quick trigger execution of the function task when its time slice arrives by using timer interrupt. By the previous means, the method realizes the cycle synchronization between the execution of FBs and EPA deterministic communica- tion so that it prevents the invalid executions of FBs in the EPA system. The experimental result shows that the method reduces the communication load so that it improves the real-time performance of the EPA system.
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