In order to measure the signals, you'll need a pure sine wave transformer as you have to add a filter to remove the 60hz power to see only the DCS signal. Then you need to whack together a little filter to knock out that 60hz signal, and the result will be just the DCS signal. I set the DCS remote operating mode to SPEED and make sure there's an engine loaded in the remote. You can then press the STARTUP button whenever you want to see the DCS signal, the SPEED setting prevents the remote from stalling when it doesn't hear from the engine.
Once you get everything hooked up, you should see something like this. The amplitude of the signal should be at least 10V P-P. Ignore the overshoot spikes and look at the actual signal, the denser part of the waveforms.