This paper presents an open architecture CNC system for wire-EDM. The main part of the system is integrated combination of a real-time operating system running on a digital signal processor (DSP) board and a Window-based environment running on a PC. The hardware system consists of a master PC, DSP-based control card, an input-output interface card and a network card. The software system consists of operation, machine logic control, motion, machining process control, interpreter, man machine interface and communication. The proposed CNC system is featured with open architecture human machine interface, flexibility, modularity and Internet connectivity. The original CNC system has been superseded in a commercial wire-EDM machine by the developed CNC system. Experimental results verified the usefulness of the developed CNC system in manufacturing automation.