Development of an open CNC based on industrial Ethernet

The conventional CNC lacks of flexibility for network and integration in manufacturing, because of its close architecture and network shortage etc., one of the effective measures to solve the problems is ONC (open numerical control). But the ONC based PC cannot carry out open architecture from core, results in resource wasted seriously and needs to study its reliability further. This paper proposed a networked ONC based on Ethernet to achieve the real-time seamlessly data exchange for CNC in distributed environment. The ONC is constructed by main control board based on ARM microcontroller, motion controller (based DSP and CPLD), realtime OS of RTLinux and user graphic interface of MiniGUI. Then the scheduling hierarchy of real-time system was analyzed and three commonly used approaches to scheduling real-time systems were introduced. Hierarchical scheduling schemes of the Networked ONC were designed in this paper. To evaluate the performance, some tests were put forward. The results testify that ONC based on open source software and the transparent model of Ethernet can meet the needs of modern manufacturing.