RS232 Cable Splitting

I'm in the process of upgrading our CNC communications system which is pretty old and many of the serial cables are failing. I've got the Moxa W2250A units setup but I'd like to install them inside the controller to minimize exposed cables and also to be able to draw power from the Fanuc controller using pin 25 which supplies +24V. From what I've read, this seems doable.

I'd also like to leave the female DB25 RS232 at the side of the machine should there be an issue with the wifi so we could send/receive programs using the old method (I would just leave the existing rs232 cable in the machine area).

I was thinking about getting an internal board like the picture attached but the company that produces them sells them as a kit and manufactures them at low volume. They're well over $200 for the board and some cables.


So to save an on costs, I'm trying to just wire it up myself. I'm wondering, does anyone know if I can just use split the RS232 connection inside the fanuc controller, connect the split ends to the MOXA unit and the other split end to the external DB25 rs232 port, allowing for someone to attach a cable to it? I'm thinking this would work as long as both lines aren't being used to send data to the CNC. We'd also only be using one end of the cable for reading at a time.

try the link below
2-Way Manual Push Button DB25 Serial Parallel Port Switch Box | ShowMeCables.com

MrAlex said:

...So to save an on costs, I'm trying to just wire it up myself. I'm wondering, does anyone know if I can just use split the RS232 connection inside the fanuc controller, connect the split ends to the MOXA unit and the other split end to the external DB25 rs232 port, allowing for someone to attach a cable to it? I'm thinking this would work as long as both lines aren't being used to send data to the CNC. We'd also only be using one end of the cable for reading at a time.

Click to expand...

A long time again we split a serial feed with a box and it worked fine but it totally depends on your machine. Back then we did it with old Makino FNC's and it worked but we have a Matsuura which freaks out if the cable is disconnected, even if there are no programs going uploading or downloading.

Thanks for the input! I'm surprised at how cheap those switch boxes are.

I'm going to try with just the cables themselves and if, like Qwan said, the machine freaks out, I'll just add the switch box.