Cnet I/F System is used for communication between the main unit and external devices using RS-232C/RS-422 Interface. The K80S has a built-in RS-232C port and has also G7L-CUEB for RS-232C, G7L-CUEC for RS-422. It is possible to construct communications systems on demand. (10 points modules include RS-232C and RS-485 ports on the main module, and no external communication module is available)