Research On The Real-time Scheduling Of Industrial Ethernet Based On EPA For Application In Coal Mine

EPA ,Ethernet for Plant Automation, is a international standard about industrial real-time Ethernet,which was developed by our country itself.Micro-segment is an element part of EPA network. In order to implement the real-time scheduling in micro-segment, it is necessary that the rate to generate data in a node suits the delay to transmit it in the micro-segment. On the basis of the real-time scheduling theory and classical algorithm RM and EDF, the thesis proves the sufficient and necessary conditions for feasibility of EPA scheduling algorithm in a micro-segment, completes the theoretical basis of EPA scheduling algorithm and gives a solid foundation to develop EPA technology further.Micro period and the offset are two key parameters of EPA scheduling algorithm, how to determine them decides the implementation of EPA scheduling algorithm. The thesis gives a novel method to calculate the micro period of a micro-segment and offsets for every node in the micro-segment, which implements hard real-time with the help of multi-periods in a micro period and is proved feasibility theoretically by the author.Time division scheduling is a key technology to implement the real-time in Ethernet. EPA realizes the time division scheduling through adding a sub layer to schedule the time slice to nodes, under the support of a precise synchronous clock. EPA allocates the fix time slice to every node before running the network; therefore it does not suit a variation environment like coal mine, which has changes in time slice to transmit data and changes in number of nodes when networks work. Author comes up with a dynamic method, MEPA_SaSiS, to allocate time slice according to the practical need of every node, and put forward an idea to implement it using a event-driven way replaced to the time-driven way, so that attains a stable channel utility ratio of 92.93 to 99.26 percent. Furthermore author brings forward some measures to feel the fault nodes off and recover nodes up on line, so as to implement the fault-tolerant scheduling with the way of both the even-driven and the time-driven.In the industrial Ethernet of coal mine,it is general situation to transmit data from a node in a micro-segment to a node in another micro-segment. Because EPA real-time scheduling can only be realized in a micro-segment, author raises a new real-time scheduling algorithm , MEPA_SaSiS, to realize the transmit data across two micro-segment, which bases on EPA scheduling algorithm and changes the filter rules across segments in EPA scheduling algorithm.There are 56 figures, 1 table, and 136 literatures.