What You Need

This is a description of what is required to connect to 90% of CNC machines.
All machine controls are different and there is no standard of what their settings should be, but the newer they are the more likely they would work with these settings. Your machine could be different, but this is for those who need a place to start.

Here are the pieces necessary to connect to most machines.

• A. - A computer
• B. - Since most computers don't have serial ports on them any more, they have USB ports instead. So you need a USB to serial port converter. These have a 9-pin connector. See Here.
• C. - An adapter if the cable is 25 pin and the USB converter is 9-pin.
• D. - A Serial Cable. There are 25-pin serial cables and there are 9-pin serial cables. The plug an the CNC machine is always a 25-pin plug so you could have a 25-pin cable, or use a 9-pin cable with adaptors on the end. They would both work because only a few of the pins are used anyway. And the adapters always connect the right wires.
• E. -  A Null Modem. This is just a connector that switches the wires inside so the transmit wire on the one device will connect to the receive wire on the other device etc. The is always mandatory.
• F. - Optional. This is an inexpensive little connector that has LED lights on it. You can see when some signal goes through the cable. When you have been trying to connect to a machine and absolutely nothing happens, this is the only way you can tell if anything is being sent through the cable at all.
   

These can all be purchased at Radio Shack or other computer store.

Serial Format Settings - In Configuration - Serial Format most machines will be set to 7 Data Bits, 2 Stop Bits, Xon/Xoff Handshaking, ISO Format, CR/LF End of Line, Even Parity.

Baud Rate would be 9600 or 4800 or 2400. With newer machines at the higher value.

The dropdown box on Comm Port should list what ports are available on your PC.

Back