Nc System Built-in Soft-plc Design

Nowadays Programmable Logic Controller (PLC) is being used widely. There are two categories of PLC: Tradition PLC and Software PLC. PLC has gradually shown its shortcoming with the application of PC-based motion control (usually called SoftPLC). SoftPLC is the major controller in this industry because of its low R&D cost, simplicity and efficiency. SoftPLC is a software which embedded PLC in CNC system-a software control platform. The PLC with CNC system becomes an independent software system in an operating system which has been combined together. The PLC with CNC system in an operating system enhances the traditional PLC's function such as the task control. It becomes more flexible and convenient. The weakness of traditional PLC such as its being incompatible with various programming language, incompatible with other machine and the "closed" source code, have been enhanced by SoftPLC.The traditional PLC is investigated before it was changed to SoftPLC. The explicit function of the system was the core function and system flow process, which was the analysis of system, architecture, Ladder Diagram Editor, image converter, and core kernel. The data structure of the Sequential Function Chart, storing of Ladder Diagram, and the edition of Ladder Diagram has become more user-friendly. The improvement of effectiveness of the physical I/O interface is the main goal of I/O. Comparing to other similar system, SoftPLC is much more independent. It needs a serial port to be connected to the PC-editing program instead of a driver in the control panel. A platform for the running process of the program is downloaded when it is connected. Moreover, it also could be edited, run and monitored from the control platform. The program debugs and modifies on the control platform with the SoftPLC. The operating system and scan cycle are verified by executing user applications, inputting signal and system diagnostics .