Manufacturing equipments should be integrated to construct CIM (Computer Integrated Manufacturing) environment, but several economical and technological difficulties may be arisen in case heterogeneous systems are integrated into each other. MMS (Manufacturing Message Specification) can be effective in such a case, but the problem is that MMS-related products are comparatively expensive and the existing manufacturing equipments mostly do not support MMS. This study was focused on developing a gateway suitable to a non-MMS-compatible CNC machine-tool, and on implementing OSI(Open System Interconnection) upper layer on TCP/IP. The development system was applied to a cell controller by means of heterogeneous equipments under CIM environment, and to evaluate interoperability and portability.