The Study On SoftPLC Of Open NC System

Open numerical control system is the research hotspot of NC technology now. With the development of the performance of high speed, high efficiency, high precision and intelligence, more and more functions which makes the software carry out all of the NC functions and minimize the scale of hardware are demanding. Machine logic, the kernel of the whole motion control, is necessarily realized through software too, which accelerates the development of SoftPLC.This paper designs the software and hardware platform of SoftPLC in the Open NC system based SERCOS interface, on the base of which SoftPLC system is developed. The SoftPLC system consists of two parts of contents, one is SoftPLC developing system, the other is SoftPLC running system simulator.At the beginning of SoftPLC developing system, users work out the ladder diagram, then checked by SoftPLC developing system according the principle to find if there is some logic errors. If no error occurs, the ladder diagram can be transferred to C program which works as the input of the SoftPLC running system simulator. The special compiling program for PLC is not programmed in this paper, and the SoftPLC program is compiled by the compiler of VC++6. 0, then be executed.The SoftPLC running system simulator in this paper is designed according the "Cycle Scan" work mode of PLC. In every working cycle, PLC go through three steps to run program, which include input sampling, executing users' s program and output refurbishing. This paper introduces the timer offered by windows to realize "Cycle Scan" and achieves.The SoftPLC system introduced in this paper is only an attempt to realize logic control in the open NC system based SERCOS interface. With the increase of experience and knowledge of the programmer, the functions supplied by the SoftPLC system will become more complete and more powerful.