Research Of SoftPLC And Developing System Based On PC

With the development of industrial control technology, the disadvantages oftraditional PLC have gradually emerged. PLC of different manufacturers are mutuallyexclusive. Though most of them have the same programming language, the company'sconfiguration, address, grammar are inconsistent. Most PLC manufacturers have theirown software, which is expensive and has poor universality. Much software even hasto run in DOS environment. All the disadvantages make users feel inconvenient; theconflict between users and PLC is becoming more and more serious.SoftPLC is a new control technology which has developed rapidly after theestablishment of IEC61131-3 programming standard. SoftPLC is based on PC, has alot of advantages such as good openness and low cost. SoftPLC works like traditionalPLC, which can be divided into two parts: developing system and running system.The running system downloads the program which is developed in the developingsystem. From this way, the softPLC realized control function.Because softPLC is based on PC and PLC, this paper firstly gives a briefintroduction of PLC and PC, then descripts the 5 programming language defined bythe IEC61131-3 international standard. After explained how the PLC work, weanalyze the composition of PLC developing system. Further, according to therelationship between function and softPLC, we divide the developing system into twosections: generic section and special section. Generic section is mainly responsible forthe programming, while the special section's work is to compile the PLC program andcommunicated with the running system..This paper's aim is to propose a softPLC solution whose running system can becomposed of different hardware platforms. The key to achieve this target is to developa developing system which can be suitable for variety of hardware platform.Therefore, users can use it to program for different hardware platform, they no need tolearn new programming languages. Even, they can directly use programmed codes, which could save the programming time. Due to so many advantages, the developingsystem is of great practical significance. Naturally, the research of developing systemis the most important..The test proves that the developing system of soft PLC realizes theladder-diagram programming function and instruction list programming. At the sametime, the code of communication with running system has been given as well as amethod to compile the program has been found.