Abstract: A functions blocks execution method is proposed on the base of EPA deterministic scheduling mechanism to improve the operation efficiency and the communication performance of EPA （Ethernet for Plant Automation） real-time ethernet systems. The method integrates all the function blocks which need EPA communication in an EPA device into a function task and determines the execution rule of the function task according to the period synchronization principle between the function blocks execution and the data communication in EPA systems：the function task must be executed only once in a macro cycle, if the periodic messages transmission window period is enough for the execution of the function task, the function task will be executed when the periodic messages transmission task is completed; if the periodic messages transmission window period is not enough for the execution of the function task, the function task will be executed when the nonperiodic messages transmission task is completed. The experiments prove that the method can accomplish the synchronous implementation between the function task and the communication task, and consequently can improve the operation efficiency and the communication performance of EPA systems.

Key words: real-time ethernet, control system, communication performance, function blocks

摘要： 为了提高实时以太网控制系统的运行效率和通信性能，在EPA（Ethernet for Plant Automation）确定性通信调度的基础上提出了一种功能块执行方法。该方法将现场设备中所有需要远程通信的功能块整合为功能任务，并且按照功能块执行与数据通信周期同步的原理确定了功能任务的执行规律：功能任务在单个通信宏周期中只能单次执行，当周期报文空窗期满足功能任务执行需求时，功能任务在周期报文传输任务结束时执行；当周期报文空窗期不能满足功能任务执行需求时，功能任务在非周期报文传输任务结束时执行。实验证明，该方法实现了系统中功能任务与通信任务的周期同步，避免了功能块的无效执行与数据的无效传输，提高了系统的运行效率和通信性能。

关键词: 实时以太网, 控制系统, 通信性能, 功能块