When ever i am testing motor switching and want to observe the pwm signals on the oscilloscope i really get confused. It looks like so many signals going high low. Are there some techniques where i can see the signals without much confusion? Please advise.

 

Keep the pulse width and frequency constant so that the 'scope can sync its trigger to them. Keep the frequency constant then the 'scope can sync and show the variable pulse widths.

 

How are you setting the sync controls?

 

Also, where are you putting the probes, and how do you have things wired?

Looking at the logic level pwm signal coming out of the control side might look a lot different than scoping what's happening at the motor terminals as a result of inductance, flyback voltage, etc.

 

Then there is always single shot.

 

4 ways

1) Use single shot as previously stated.
2) Use trigger holdoff https://www.testandmeasurementtips.com/difference-hold-off-control-delayed-sweep/
3) If DSO find a sequence in pulse train of "1s" and "0s" that you can trigger off
4) If DSO trigger off a specific pulse width/duty cycle

Regards., Dana.