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N6705C Current Measurement Polarity is Reversed?

Question asked by hammie4 on Mar 4, 2019

I'm wondering if I'm measuring things incorrectly or I've got things hooked up wrong. Here's what I'm trying to do:

 

Power a device with the channel 1 SMU (the module is a 6784A). Also measure the current through a particular part of the circuit using channel 2 as an ammeter (the module is also a 6784A). So channel 1 is set as a 4 quadrant voltage source, and channel 2 is setup for current measurement, with the leads coming out of the "output" jacks of the module (as opposed to the "sense" jacks, which seems a bit counter-intuitive, but I don't measure anything out of the "sense" jacks). When I do this measurement, the polarity of the current measurement is opposite what I expect. Why is this? I even double checked with just a simple resistor, and the current shows up as negative. Is this intended behavior? Also concerning is that when the leads are disconnected, the module functioning as an ammeter will read 0.1 mA, even though the leads are floating or even disconnected altogether. When actually measuring a current, it seeeems to be accurate, albeit with the polarity reversed.

 

Is all of this intended behavior? Should I just reverse the leads and assume everything is fine, or should I be concerned about the accuracy of the current measurement?

 

Thanks,

Matt

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