Study On The Practical DNC System Based On CAN Fieldbus

As a new method to realize equipment integration, information integration and function integration for the modern mechanical manufacturing enterprises, DNC is not only the necessary basis of FMS and CIMS implementation in enterprises, but also the key technology to the efficiency improvement of NC machine tool, which is the lowest level equipment of the mechanical manufacture system.By deep studying and analyzing the present situation and related techniques of DNC system, the practical DNC system based on CAN fieldbus is established, and its hardware system and software system are developed respectively.In the hardware system, a three-layers control structure mode– which is composed by the unit layer, DNC computer workstation layer and NC system equipment layer– is presented. Aim to the disadvantage– such as low speed, short distance, high cost and bad real-time capability etc.– in point-to-point serial communication technology and local area network communication technology which are applied widely in DNC lower level communication, and based on the good real-time capability and high reliability of CAN fieldbus, CAN fieldbus is introduced into the DNC communication system construction, the system's network topology is determined and related hardware are chosen properly. The system simplifies the communication structure, and improves the communication speed, reliability and real-time capability as well.According to their function, the software system can be devided into three modules, i.e. NC code compiling, NC code transmitting and NC machining information management. NC code compiling module is used to check the lexical mistake, grammatical mistake and semantic mistake; NC code transmitting module is used to set up the DNC system initialization, transmit and receive NC program; NC machining information management is used to manage the NC code information and other processing information that is just inputted or existed in system by database.The practical DNC system constructed in this dissertation, can verify the NC code accurately, conveniently and efficiently, can realize the realtime and reliable NC code transmitting, and can manage the NC machining information effectively too. The system has the characteristics of reliable operation, simple structure and high real-time capability, can improve the efficiency of NC machining process obviously, and has a certain application prospect in the middle and small scale manufacturing enterprises of our country.