Abstract:

Three delay factors of EPA micro segment:queuing delay,node information processing delay and transmission and propagation delay was analied,and the weight influence of the three major factors of delay on the real-time performance was discussed,through the analysis of the number of nodes in the N and scheduling algorithm factor α on the effects of delay variation,reached two conclusions:1) N=8 is the inflection point of phenomenon of "two eight"between queue delay and node information processing delay;2)when α□0.32,queuing delay will be reduced to be the secondary factors for the influence of the delay.The conclusions provide EPA network reference directions for measures to improve the real-time performance.

Key words: Ethernet for plant automation, micro segment, queuing delay, processing delay, scheduling factor;number of nodes