Design And Implementation Of Intelligent NC Soft PLC System

At present, the automation technology becomes very widespread in CNC machine tools, with the developing rapidly of today's machinery manufacturing. The end of twentieth century, the United States invent the first Open-CNC system, From then on, the CNC system into the open era. The PLC in NC system commonly used as auxiliary control unit, however, Open-CNC system needs to have the open control unit, but, the traditional PLC control unit have no the function of the open, it is unable to meet the needs of Open-CNC system. Thus, the soft PLC technology is based on the PC came into being, which can achieve functions of the traditional PLC control unit. The technology has become a key technology on Open-CNC system.The soft PLC in the Open-CNC system which is consisted of two main parts: developing system and system of Operation. Developing system is to provide users the modules of editing, compiling, and testing; Runtime is the core of the CNC machining system to perform a predetermined action, which receives the output of the object code and converted into numerical control machine code, which is recognized by the system. In this paper, the purpose is to design and implement a software PLC development system. PC is as the hardware platform of soft PLC, and the Windows operating system and Microsoft's Visual C ++ 6.0 as the development tool. In this design, the soft PLC developing system is divided into four parts, the main contents are as follows:First, the system is based on the soft PLC functions and design principles, and the necessary of numerical control system, on which designing the all structure of the soft PLC development system, and use the Programming ideas of modular design, the development of the entire PLC system into edit, compile and simulate three functions module.Next, a detailed description of the development of system function module design and implementation. Object-oriented C ++ high-level programming language to complete development system function module, document and use MFC serialization mechanism to implement elements of the ladder logic to save and load. Design Compiler and detection system, based on the logical structure of the ladder, according to a binary tree scanning algorithm traversing positive, ladder compiler module will be converted into the equivalent List program.Third, detailed design and implementation of logic test module, the module is mainly achieved by running lights logic test, according to the ladder logic element input and output signal can enable the corresponding position, by observing the signal to determine the logic program is correct, the logic module of the completion of the program logic test.Finally, a brief description of the data between the CNC system and soft PLC information interaction interface design. The storage mode of open CNC system software PLC instruction information and data, the programming information soft PLC and data as a shared data stored in the shared area of operation of the system is accessible, effective transfer of data between the CNC system, Runtime data into the CNC system code can be identified by a numerical code system based on CNC machine tools for electrical control external devices.