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工业自动化采用以太网协议,参考了传输控制协议/网络协议的组织方式,分为物理层、数据链路层、网络层、应用层,并在其上层增加了用户层。在数据链路层,将用户层的报文分为周期报文和非周期报文,根据设备组态信息,使周期报文按照固定的时间片发送,而非周期报文按照报文优先级大小发送,即确定性调度。运用该技术使以太网工厂自动化网络有效地避免了乱序、丢包、重发报文等情况,保证了以太网网络中报文传输的确定性和实时性。测试结果表明,所提出的调度算法完全符合以太网协议规范,精度可达到微秒级。
Industrial Automation uses the Ethernet protocol, referring to the transmission control protocol / network protocol organization, is divided into the physical layer, data link layer, network layer, application layer, and in its upper layer to increase the user layer. At the data link layer, user layer packets are divided into periodic packets and non-periodic packets. According to the device configuration information, periodic packets are sent according to a fixed time slice. Non-periodic packets are sent according to the packet priority Send size, that is, deterministic scheduling. The use of the technology to Ethernet factory automation network effectively avoid the disorder, packet loss, re-send the message, etc., to ensure that the Ethernet packet transmission in the certainty and real-time. The test results show that the proposed scheduling algorithm fully conforms to the Ethernet protocol specification and the accuracy can reach microsecond level.