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Cable Loopback Tester

We often get asked the same question over and over again - dnc4U has suddenly stopped sending (or receiving) files - we haven't done anything to the settings (honest!).

The first question we ask is - are you sure the cable is OK?

So many times the cable has been trailing on the floor and one of the wires have been cut through with metal swarf, or someone has accidentally kicked the cable whilst it is connected to the CNC and pulled out some of the wires, especially after years of use when the cable sheaths become hard and brittle.

One of the easiest and quickest ways to test your cable is to use our loopback tester....

Take the cable out of the CNC and form a loop on the transmit & receive pins (pins 2 & 3). You can use some wire, or just hold a paperclip on the pins. OK, ours is a 9 pin and it's female - yours is probably 25 pin and male, but you get the idea.



Then in dnc4U, click on the top menu bar Debug >> Loopback Tester to open up this window.

If you click the Send Test String, it will send the characters, and if the transmit & receive wires form a loop, you will see the characters get echoed back. If you see the characters, your cable is OK in so far as transmit & receive wires are OK. If you don't see anything, you need to investigate your cable for cuts & breaks in the cable or D-connectors.

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