为了找到评估和改进EPA工业以太网通信实时性的方法,对EPA非周期报文的通信实时性能进行了研究.通过分析EPA网络的通信调度机制和延迟产生机理,根据报文进队时机的不同,建立了4种非周期报文进队模式,并且分别对各个模式的调度特征、通信延迟和相互影响规律进行了分析,提出了非周期报文通信实时性理论模型.通过理论分析和实例验证,发现3个制约非周期报文通信实时性的主要因素:①非周期报文传输的优先级反转;②通信调度机制的开销;③放弃发送权竞争后进队报文的处理方式. In order to find a way to evaluate and improve the real-time performance of EPA industrial Ethernet communication, the real-time performance of EPA non-periodic message communication is studied.According to EPA communication scheduling mechanism and delay mechanism, , Four kinds of non-periodic packet entry mode are established, and the scheduling characteristics, communication delay and interaction rules of each mode are analyzed respectively, and the real-time theoretical model of aperiodic packet communication is proposed.Through theoretical analysis and case verification , And found that the three main factors restricting the real-time communication of non-periodic message: ① priority inversion of non-periodic message transmission; ② communication scheduling mechanism overhead;