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The network delay of the periodic messages transmission in the network control system (NCS) basedon Ethernet for plant automation (EPA) is analyzed from the theoretical and experimental perspective inthis paper. The composition and the characteristics of the network delay of EPA periodic messages transmissionin a subnet is studied through analyzing the information transmission regularity and EPA deterministicscheduling mechanism. On this basis, the queuing delay at communication schedule management entity(EPA_CSME) that is the most important component of network delay is analyzed, during which theformulas for the queuing delay of periodic messages and other real time parameters are proposed. Furthermore,an experiment is developed to test each component of network delay of periodic messages transmissionin a EPA subnet. According to the experimental and the theoretical analysis, the conclusion is drawnthat the delay during which the periodic messages wait for the periodic messages transmission time slice isthe main factor that causes considerable network delay, and improvement method is presented.
The network delay of the periodic messages transmission in the network control system (NCS) based on Ethernet for plant automation (EPA) is analyzed from the theoretical and experimental perspective in paper. The composition and the characteristics of the network delay of EPA periodic messages transmission in a subnet is studied through analyzing the information transmission regularity and EPA deterministicscheduling mechanism. On this basis, the queuing delay at communication schedule management entity (EPA_CSME) that is the most important component of network delay is analyzed, during which theformulas for the queuing delay of periodic messages, and other real time parameters are proposed. Furthermore, an experiment is developed to test each component of network delay of periodic messages transmission in a the EPA subnet. According to the experimental and the theoretical analysis, the conclusion is drawnthat the delay during which the periodic messages wait for the periodic messages transm ission time slice is the main factor that causes considerable network delay, and improvement method is presented.