Performance Analysis Of EPL And Its Application In DCS System

With the development of the industrial control system, industrial control network has gone through changing from Field Bus to Industrial Ethernet. Industrial Ethernet, for its high bandwidth, superior real-time performance, good openness, powerful resource sharing ability, has become the most attractive solution. As one of the industrial Ethernet protocol families, Ethernet POWERLINK has the advantage of hard good real-time performance, open source, easy to use etc, therefore, it has a good prospect of being widely used. Nowadays, the research of EPL are mainly focus on the real-time performance of the protocal and its engineering application in motion control. Based of the existing achievements, this paper studied EPL protocol in depth, from multiple perspectives including protacal architecture, performance analysis, synchronization mechanism, platform implementation and application in distributed control system.The main research work is as follows:1) The two communication modes of EPL, including Preq/Pres and PollResponse Chaining, have been studied. Firstly, performance analysis of the two modes was displayed in mathematical method, then, an EPL network simulation model was innovatively built by using OPNET software. By making contrast of the calculation and simulation result, a conculsion has been made, which would be useful for EPL mode selection in future application.2) Although PRC is a more efficiency communication mode, it stability is strongly depend on the measurement of the propagation delay and the calculation of Pres Response Time, so a method has been proposed to abtain the two value.3) High precision synchronization is required by a multiple of application situations. Ethenet POWERLINK has provided two kinds of synchronization mechanism:SoC frame synchronization and distributed synchronization. Since the delay of SoC will make an influence of the synchronization precision, a delay compensate method has been proposed to improve the precision in this paper.4) The implementation of Ethernet POWERLINK protocol in Linux real-time operating system and FPGA platform was described in detail. The implementation is the basis of the design of EPL MN/CN and its practical application.5) EPL protocol was applied in UWin DCS system to settle the existing problems, for exmple, the long communication cycle and low bandwidth utilization. In this paper, the whole architecture of distributed control system based on EPL was designed. What’s more, an EPL gateway was designed to link the SNet and MNet. In order to achieve high reliability, a EPL network redundancy scheme was proposed in details.