Simulation Research Of PLC

The programmable logical controller (PLC) is a general controller, which is used more widely in industrial control fields. It has become a principal controller in realizing the industrial control. However, the traditional design and debugging of PLC control system can not be separated from the hard PLC. If a virtual PLC is constructed and simulated by the computer which has the ability to realize main functions of PLC, that will be more convenient to design the PLC control system.Primary content of PLC simulation technology and realization are researched. The method of PLC communication simulation using computer serial port is also provided, and the simulation software is designedFirstly, CX-Simulator, the simulation software of OMRON is analyzed. It is generalized that primary content of PLC simulation includes PLC component simulation, I/O simulation, instruction simulation and communication simulation.Secondly, the simulation realization method is researched according to the object-oriented program (OOP) design's ideology. Program editing, offline simulating and simulation of basic sequential instructions and application instructions are discussed. The program is designed to realize simulating input signal with analog switch box and simulating output with analog PLC panel. Moreover, the simulation approach of serial communication based on the mechanism of OMRON PLC Link and Host Link is developed.Thirdly, consider OMRON CPM1A/CPM2A as simulative object, a soft named SPLC by Visual C++ 6.0 is designed, which can simulate all sequential instructions and commonly used instructions, realize statement table list editing and guiding, simulate input signals by analog switch box and output results by analog PLC panel. Furthermore, SPLC posseses other functions such as monitor and modification of register and memory, PLC Link and Host Link communication simulation.Finally, using the function of PLC Link communication in SPLC, the simulation of two elevator parallel system by two PLC is finished.This proves the validity of the simulation soft SPLC.