Measurement on Rasoberry Pi

[Gttuy]

I connected Monsoon to Raspberry Pi via USB. I am not sure whether I should monitor on main channel or USB.
If I sample from USB the output voltage is zero. Also, why the sampled current values are negative?
Sorry I am not familiar with these

[cpagravel]

If you are using banana plugs then you need to sample from main channel. Sample from USB if you use the USB input in the front of the device.

The current can be negative if the device is sinking current. There's various reasons why this might happen. I'm not an expert on this so will let someone who is more experienced comment.