Design And Realization Of The Soft PLC Developing Platform

Because the hardware of PLC trend towards standardization, people focus on the design of PLC program. The current trend of PLC programming tool is program developing software based on personal computer.Many softwares causes not only unfriendly man-machine interface, but also inconveniently operation. What is worse,some software should be used under DOS system, The main task of my research is to develop a PLC program developing system for the NC system of Hust Corporation, which provides users with an intuitionistic, convenient and high-efficient programming environment based on personal computer.At first, in this paper, the topic backgrounds are elaborated, and the significance of the research is narrated according to analysis of the problems which exit in the current research. Then, the requirements of the soft PLC platform are considered, and the overall structure of the system is designed based on software engineering.In order to meet the users' demands of low-cost, strong compatibility and openness, this topic researches and develops a platform for SoftPLC which is according to the international standard IEC6113I-3.According to the methods of the software engineering and object-oriented design, the system analysis and requirement analysis on this platform are made, and the detailed function requirements of the software are drew. And then, through the modularization design, the software is decomposed to four modules which are item management, intelligently compilation, translation and edition and simulation and emulation. After modularizing, the function of each module has been carried out. Simultaneously, data direction between the modules of this platform is designed, which deals with good news transmission and drive between them.Based on the object-orientation and write PLC program by plotting in the system, the platform chooses the ladder diagram language. Through logic tree structure, the editor links the ladder diagram and PLC instruction to realize the compiler conversion between them. The compiler conversion uses the rundle as unit, according to the direct deep prior scanning algorithm, a logic tree structure is established, and then the PLC instruction is gained by going through the tree. In view of the online modification function of SoftPLC platform and compatibility with other edition of PLC software, the platform realizes the change from PLC instruction to ladder diagram.In a word, the system realizes the standard design of ladder diagram and the auto creating formation of PLC instruction. It also raises the efficiency of PLC program, which takes on an intuitionistic edit environment and flexible edit methods.