Research Of Industrial Control Software Programming Method Based On IEC 61131 Standard

Traditional PLC is a kind of automatic control device, which is developed in the last century, and has now been widely used. It has multi-function, high reliability and strong industrial environment adaptability. In practical application, both of the PLC hardware structure and programming method of different manufacturers have great differences. PLC system does not have good openness and compatibility, which greatly restricted the development of traditional PLC.In 1993, IEC formally promulgated the international standard IEC 61131, to make PLC hardware and software platform have a unified standard. This standard has played an important role in the development of industrial control software, and since then PLC technology is becoming more and more widely applied in industrial control. Soft PLC research in China starts late, there is still a big gap compared with the technical level of foreign products. Therefore, study on soft PLC technology is of great significance.With the aim of improving this situation, an industrial control software programming system based on IEC 61131 standard is designed. Research starts from analyzing the development and status of soft PLC industrial control software at home and abroad, and introduces the generation and components of IEC 61131 and the definition of the five language specifications in IEC 61131-3. Then the structure and working principle of the traditional PLC and soft PLC control system are analyzed and compared. On this basis, through the detailed analysis on functional requirements and structure of the development system, the overall design scheme of the industrial control software programming system based on IEC 61131 is presented. Finally, thesis implements ladder diagram editing and the algorithm of ladder diagram converting to instruction list, completes the interface design, and realizes the basic function of the programming system.In order to verify the correctness of user program, a simulation module to simulate a soft PLC working on computer is implemented. The simulation module adopts the interpretive execution way, executing the user program step by step, can be used to test if the ladder diagram and instruction list program can achieve the expected function.