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Typical RS-232 wiring from PC to CNC

Typical RS-232 wiring from PC to CNC

Please note! "Standard RS-232" straight through wired, pre-made cables will not work unless you add a Null-Modem
adapter or buy a Null-modem cable where pin 20 is connected to both pins 6 and 8 on the other end.

The following diagram depicts the cable wiring between a DNC workstation’s communications port (either the standard built-in COM1 and COM 2 or RocketPort expansion ports) and most CNC’s. The numbers given are for standard 25 pin D-subminiature RS-232 connectors. On the PC side of the cable the connector must be a socket. On the CNC side it varies. FANUC and Yasnac’s, for example require plugs. Okuma’s and Cincinatti’s generally require sockets.

This wiring assumes the following for 25 pin D-sub connectors:

At the PC and the CNC pins 2 and 4 are outputs. Pins 3 and 5 are inputs. Pin 7 is logic ground.

PC (9 Pin) or (25 Pin socket) CNC (25 Pin-as required)

- - X------------------------------------------------------------- 1 shield

3   2------------------------------------------------------------- 3 RXD

 3------------------------------------------------------------- 2 TXD

7   4------------------------------------------------------------- 5 CTS

8   5------------------------------------------------------------- 4 RTS

5   7------------------------------------------------------------- 7 GND




Connect the shield drain wire to pin 1 at the CNC end of the cable only.

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