Using second XM generator in frequency measurement mode to detect broken TENS or "contact mode" cables.
Press the following buttons on the XM to select the "TTL-IO" as an Output:
This will automatically select the "EXT IN" as an Input.
Press the following buttons on the XM to select the frequency measurement Mode:
Connect a Dummy Load 50 Ohm and a BNC to banana connector to the EXT IN - BNC connector:
Then connect it to the end of the Contact pads and if there is no broken cable then this XM should show the value of the frequency.
The EXT IN input needs a minimum Amplitude of 0.5 V pp to show the frequency. If the Amplitude is lower then the Frequency Meter of the XM the generator shows 0 Hz. The dummy load 50 Ohm is used to detect also "half-broken" TENS / contact cables.
For more details, please check the link: