Real-time Communication Based on MMS+TCP/IP+ Ethernet for Embedded CNC

Networked CNC (computer numerical control) system is the foundation for realizing automation, intelligent and globalization of manufacturing. The transparent model, real-time and deterministic communication of industrial Ethernet is urgently needed. The communication platform based on Manufacturing Message Specification (MMS), TCP/IP and Ethernet is the trend of the next industrial automation communication system. This paper put forward a reference model based on MMS+TCP/IP+Ethernet to achieve the real-time seamlessly data exchange for CNC in distributed environment. The networked CNC is constructed by main control board based on ARM microcontroller, motion controller (based DSP and CPLD), real-time OS of RTLinux and user graphic interface of MiniGUI. After analyzed the effect factors of real-time communication performance, the key technologies of the platform were discussed, such as communication tasks priority of Ethernet, TCP/IP protocol over Ethernet, real-time network communication models and event-driven scheduling. Finally, and the network experimental results are shown and discussed.