The Research Of Open Style Numerical Control System Based On Windows OS

Modern machinery manufacturing industry has brought forward higher request to numerical control system, which can according to consumer's request to design promptly an open numerical control system prototype to adapt to the market request for diversifies product. It has become the direction of numerical control system development. Windows OS has multi-job operating characteristics and supports multi-thread that may realize real-time multi-job control of numerical control system. So under the Windows OS platform, it is an important development direction of open numerical control system. This article completed main research work as follows:1.In view of comprehensive analysis development trends of open style numerical control system as well as shortcomings of the traditional numerical control system, this article put forward to based on Windows OS platform and used IPC machine+motion control card mode and master-slave structure of NC system to research and develop the open numerical control system. With GT-400-SV motion control card as the CNC machines next-bit machine's core, a real-time multi-axis motion control unit was constituted. With IPC machine as the host computer, the tasks of non-real time were carried out. Through the bus communication, dual-port RAM communication and the development of the upper and lower machine data transmission protocol, the article ensured upper and lower machine real-time data communication. A linear and circular interpolation, motion acceleration and deceleration control of the content of real-time motion control were achieved. Based on the analysis of demand, with IPC as the hardware foundation, according to numerical control system functional, the system hierarchy model was designed. The system topology structure and implementation of an open approach to the system were given. The hardware and software structure of system were designed.2.In the hardware architecture, the modular method was used to build and expand the hardware system. IBM-PC bus standard was chosen as functional modules connected standard bus. A number of EISA slots were selected to constitute a hardware connection motherboard. The basic framework of CNC was built by plugging the standard request of micro-computer board (the upper machine) and motion control card (the lower machine). Users can expand the numerical control system's hardware by plugging functional blocks which conform to the IBM-PC main line standard to satisfy system requirements. The openness of system hardware was realized.3.In the software architecture, the upper computer ran mainstream OS. The lower machine ranμc / OS real-time embedded computer operating system. According to the time constraints of software functions of CNC system, they were divided into strong real-time tasks, weak real-time tasks and non real-time tasks. According to the hardware I/O performance requirements, they were divided into operating and non-operating category. Motion controller carried out strong real-time and I/O operations tasks. Various functions were encapsulated. A common functional class library was established. Application programming interface (API) was defined which users could extend the user-specific software function to the system. The certain openness of system was enabled .4.In view of the characteristics of multi-task control of numerical control system,under the windows platform,the multi-threading, task scheduling strategy and the inter-process communication were deeply analyzed. Then according to the characteristics of numerical control system function, the system tasks were divided into system overall control process, the human-machine interface process, the trajectory planning process and motion control process. Each process was also divided into relatively independent of functional sub-thread. The CNC system realized the weak real-time control tasks by setting the thread priority, using multi-threading scheduling policy and interrupt mechanisms. The CNC system realized the powerful real-time control tasks by the lower machine. The inter-process communication were realized by using the messages, sharing memory and named pipeline three kinds of communication mechanisms. The system made each functional module coordinate to complete the processing tasks.5.In the numerical control system software development, the VC++ was taken as the development tool. The object-oriented modular method was used to design the human-computer interaction interface software modules, processing pre-processing module, decoding module and interpolation module. The upper machine to numerical control processing code compilation, system parameter settings and tool compensation function were achieved. The motion control functional module was developed. The numerical control system realized many basic functions, such as return to the reference point, jog control, incremental control, the moving control of acceleration and deceleration, spindle control, the feed adjustment function and so on.The debugging results indicated that the numerical control system was built and designed by using motion control card + IPC machine pattern. Motion control card was taken as real-time motion control's core of the system. Software system man-machine interface was friendly. The components maintenance was convenient. Many kinds of motion control functions were realized. It made the system have certain openness.