Abstract: Field-bus application is an inevitable development trend of numerical control (NC) system. In order to meet the NC system’s high demand for reliable communication, based on the analysis of relationship between machining accuracy of NC system and reliable communication, a reliable communication mechanism of field-bus is designed. For this mechanism, an evaluation indicator for the communication reliability of NC system is established, and it is proposed that the fault-free communication time is used to measure the reliability of field-bus communication. Then by using the probability statistics method, mathematical analysis of the mechanism reliability is carried out, and the relation between the field-bus communication reliability and the number of communication stations and the maximum times of retransmissions is obtained, and their respective influence degree is analyzed. Simulation experiments verify the correctness of the theoretical analysis results, and the effectiveness of reliable communication mechanism applied to NC system is proved through the actual electromagnetic interference testing. The theoretical study and experimental result have important guiding role in reliability design and analysis of NC system communication.

Key words: Field-bus, Numerical control system, Reliability analysis, Reliability Evaluation, Reliable communication