Research On Real-time Strategy Of EPL And Its Application In The SOE System

In recent years, the industrial control network has played an increasingly important role in industrial control system. Timeliness is vital for the industrial control network, whether the field bus or the industrial Ethernet. The real-time Ethernet becomes the most attractive solution in the area. With the advantage of real-time performance, open source, and easiness to transplant etc., Ethernet POWERLINK (EPL) protocol has been widely applied to industrial control systems. Up to now, compared with the major focus on the engineering application of EPL such as motion control, the simulation analysis of EPL mechanism model is relatively scarce. This Master's thesis studied EPL protocol in depth, from multiple perspectives including protocol architecture, software implementation, mechanism modeling, real-time strategy simulation and application etc.The main contributions are listed as follows:1) The implementation of EPL protocol in Linux real-time operating system and FPGA platform was described in detail.2) EPL network simulation model was innovatively built by using OPNET software:The DLL process models were built according to EPL DLL state machine; MN and CN node models were built according to the hierarchical structure of EPL; network model was built according to the industrial network structure.3) The synchronous real-time performance of EPL was studied through the research of end-to-end delay of synchronous data transmission. The following conclusions were obtained from the simulation results:the ideal end-to-end communication delay is independent of the number of nodes, proportional to the frame length, and inversely proportional to the communication rate; synchronous real-time performance of EPL is far better than that of Ethernet, which can completely satisfy the requirements of real-time control.4) The asynchronous real-time performance was studied through the research of response delay of asynchronous alarm data. A new asynchronous real-time alarm processing strategy compatible with existing EPL protocol was proposed. Based on it, the asynchronous real-time performance was verified in three simulation scenarios.5) EPL protocol was applied to UWinSOE system to address the problem of SOE records missing due to high frequent events. At the same time, a new clock synchronization method based on GPS was proposed with its precision up to microsecond. The designed SOE system using this method could accommodate millions of records with its resolution up to 0.5ms. This example extended the application range of EPL protocol.