Windows Open Cnc System Software Design And Research

This paper introduces how to design and implement the open architecture software system with three-coordinate Computer Numerical Control (CNC) based on motion controller GD104 on the Windows98 platform. The software system is divided into motion controller driver software and host application program under the hardware environment, and both of them are designed and developed respectively. Meanwhile, some key problems in the CNC system are analyzed and researched, and some important achievements have been gotten as following:(1) In terms of Numerical Control (NC) code compile, many complex operatings are put into preprocess with the compile and interpretation method, while less memory is used to realize the transformation from NC code to interpolation commands during the realtime process. At the same time, the tool semidiameter compensation problem is also solved by analytic method in preprocess stage.(2) In terms of graphic emulation, tool track is provided with the preview mode of three-view, and it is dynamicly traced by using Bresenham's algorithm during the simulated working process. The working time is accurately estimated according to its speed.(3) In terms of interpolate algorithm, the parts are interpolated for two steps by using PC computer and motion controller mode. In the first step, the PC computer assigns a thread to finish the task of rough interpolation. In the second step, the task of exact interpolation can be finished eithor by the hardware of the motion controller or by the bit-interpolation of the motion controller after the PC computer generates the data package.(4) In terms of realtime control, the interruption capture of the hardware timing and interpolate ending are solved by Virtual Device Device (VxD). A speed control algorithm is used to control the realtime position in closed-loop control system. Main thread, control thread, interpolation thread and interpretation thread are adopted to finish the realtime working process of NC machine by using synchronism and communication among these threads.At last, the development of motion controller driver software and host application program is finished, and the results of the applied experiments show the CNC software system is satisfactory.