How to display differential between probes?

[crokusek]

I just received the OpenScope and am impressed.  I understand each of the 2 probes is single ended and although the ground pins for each probe are separate, they are both really common earth ground (same as 3rd conductor power plug).  Please correct me if that is not right.

So to take a differential measurement can I probe 2 points and show the difference Osc1 - Osc2 in Waveforms Live?  I don't see a difference icon in WFL.  Seems like it should be a built in feature.

Thanks, Chris

 

[JColvin]

Hi @crokusek,

That is correct that the grounds for the two analog inputs are not isolated, so they are a common ground to the OpenScope MZ; I wouldn't necessarily call it an earth ground since the OpenScope MZ can be powered by a portable USB charging device, but I think you have the correct idea.

I haven't seen a way within WaveForms Live to automatically measure the difference between the two oscilloscope measures either in real time or after an acquisition has been made. I will ask another one of our engineers more familiar with WaveForms Live if such a feature is available or planned.

Thanks,
JColvin

 

[JColvin]

Hi @crokusek,

I heard back from one of the other engineers; while a direct plot of the difference in voltage is not directly available, they did let me know that you can use the Cursors option to emulate this functionality a bit. By setting the Cursor type to Track and setting the Cursor 2 Channel to Osc 2, you will be able to see the measured voltages at each cursor and the associated delta-X (time) and delta-Y (voltage) between the two points, though they did let me know that these deltas are absolute values so the sign may need to be adjusted as appropriate.

Naturally, this only gives you information at a single data point, so if the type of measurement you are taking supports it, I would recommend capturing a sample and then export the data in a .csv and manually calculate the result from there for the entire acquisition.

Thanks,
JColvin

[crokusek]

Thanks for checking and the detailed workaround!  Hopefully a native diff mode will eventually make it into the software eventually.