The CNC controller is the termination executor located at the end of the whole manufacturing chain. The current CNC is relatively isolated from the upper planning and manufacturing modules owing to the older data interface ISO 6983. Furthermore, lack of effective integration of heterogeneous information at the distributed automation environment is becoming increasingly evident. As a result, the development of CNC's intelligence and integration is heavily restrained. In this paper, a unified communication framework is proposed, which takes STEP-NC as the information input from CAD/CAPP/CAM and adopts the real-time industrial Ethernet fieldbus for controlling and monitoring at the device level. Based on this framework, a knowledge base modeling approach using ontology theory is addressed. The validation of combining this communication framework with the open and intelligent CNC is also discussed in the end.