关键词: 以太网工厂自动化, 通信调度实体, 确定性调度, 宏周期

Abstract: According to TCP/IP protocol, Ethernet for Plant Automation (EPA) protocol was divided into physical layer, data link layer, network layer, and application layer, additionally user layer was added above. On the data link layer, packets from user layer were divided into periodic packets and nonperiodic packets. In terms of configured information beforehand, the periodic packets would be sent by fixed time block, while the nonperiodic packets would be sent by their priorities, which was called confirmed scheduling. The technique mentioned above was applied in EPA network to avoid disordering, missing or resending packets effectively, which insure the confirmation and realtime of the packets. Test result showed that the arithmetic satisfied the EPA protocol and the scheduling precision could reach the microsecond level.

Key words: Ethernet for plant automation, communication scheduling management entity, confirmed scheduling, macro cycle