Abstract: For the asynchronous and synchronous communication of computer numerical control (CNC) fieldbus, a message safety communication method which adopts dynamic cyclical redundancy check (CRC) upon the application layer is presented. The structure of CNC fieldbus safety message is proposed, and safety communication method based on dynamic CRC check and algorithms are deeply researched. And then mathematic method and experimental tests are adopted to compare the performances of the new and traditional methods. The results prove that the new method can meet the real-time performance, reduce residual error rate obviously, achieve the requirement of message integrity rating completely, and be more suitable for the application of message safety communication in CNC fieldbus.

Key words: Computer numerical control fieldbus, Dynamic cyclical redundancy check, Residual error rate, Safety message