The Research On Configuration Control Strategy Embedded In PLC

Traditional programmable logic controller (PLC) mainly realizes the logic control abilities, and has nothing to do with complex process control, in addition, its implementation is too verbose. As the analogue programming is too complex, it is not fit for PLC to be used in process control. Considering the premise of accurate logic control, modern industrial control demands more for process control. This paper studies the implementation method to combine the process control strategy with PLC trapezoid graph, so that the method not only has an import realistic significance and practical value for the development of PLC technology, but also may be an guidance for future PLC novel research of our country.Based on graphic programming, this paper implements the technology of control strategies generation using configurable software development method. Users can generate their control strategies by dragging graphic component; furthermore they can embed the generated strategies into ladder diagram according to the requirements. It is an initiate and innovate work to achieve logic and process Hybrid Control by ladder diagram. The main works of this paper are as follows:Based on component-based development approach, this paper proposes general configuration software model, which realized the separation between content and representation. This method use XML description language to save the information of function components. So the configuration component is easy to cross platform and extensible. In order to be convenient for the user customize the basic function block through function library, this paper realize an automatic generating system for component which improved scalability.To overcome the drawback of common control loop recognition algorithms, this paper propose a new common control loop recognition algorithms based on double stack. Using XML matching XSLT template technology, the control algorithms packet generate automatically. Then source code automatic generation from upper computer is accomplished, which greatly improve the stability of the system. By.NET technology, to achieve general control strategy configuration design platform and graphical configuration, it is convenient to use and control the management strategies.Finally, based on the generated configuration control algorithm, this paper proposes a method of configuration control algorithm embedded in PLC Ladder diagram, the overall architecture and implementation is presented. The task of ladder diagram program consists of fast logical events, slow logical event and configuration tasks. The three aspects of process communication, task scheduling and memory management is analyzed and the implementation is given. Control algorithm instructions on the PLC ladder diagram platform run successfully, the feasibility and the credibility of this system are proved. This paper achieves a PLC ladder program combined with the control algorithm, which expanded the scope of application of the programmable controller and improved control flexibility greatly.