Research On The Software Of Open Cnc System Based On BECKHOFF TwinCAT

With the characteristic of opening, universal and compatible with each other, the open CNC system has solved the closed issues of traditional CNC system, well adapted to the needs of medium and small batch in modern manufacturing and become an important direction of modern CNC system.This paper analyzed three basic structural forms of the open CNC system based on PC, and used the structure of"PC + the motion controller". The software development of open CNC system was carried out based on Motion controller and other hardware components, which were Germany BECKHOFF embedded computer. According to the different requirements of real-time, the software of open CNC system can be divided into two parts: the PC software and the lower position machine software.The lower position machine software, also known as lower computer control software, had stronger real-time, achieved the real-time control functions and was developed by TwinCAT PLC. It consisted of the operation selection module, program preprocessing module, decoding module and interpolation operations module. The operation selection module was the core of software development, and was designed to three modes: Automatic interpolation mode, MDI mode and Jog mode.The PC software, also known as PC management software, had weaker real-time and mainly completed non-real-time control function. It was developed by VC++ software, which included the initialization module, program editing module and communication module. The initialization module mainly accomplished initialization of communication port and parameters. Program editing module achieved the programing, storage and downloading functions. Communication module completed communication function with lower software by adding the dynamic link library TcAdsDll.After the completion of software development, it can be tested in a virtual operating environment provided by TwinCAT System Manager and modified for unreasonable functions. As the deviation between the virtual environment and the actual operating environment, it was necessary to take experiments. The experiment mainly verified motion control function and trajectory control function of open CNC software, to determine whether the software can perform basic interpolation control. Virtual operation test and experiment were combined for verifying the feasibility of the software control.