Source Measurement Unit Disconnected Remote Sense Lines Behavior

Updated Oct 2, 2018

Reported In

Hardware

  • PXI Source Measure Unit

Driver

  • NI-DCPower

Issue Details

I've configured my NI SMU for remote sense, but when I disconnect the remote sense lines I still see a reading and do not see an error.  Why do I still see a reading without the lines connected?

Solution

To help prevent an uncontrolled output voltage, the HI/LO lines are tied to HISense and LOSense respectively through large value resistors (either 100k or 1M depending on SMU).  When the sense lines are disconnected, you still read the voltage at the HI/LO terminals to control the output.  This will result in a less accurate voltage output, and remote sense should not be configured if the sense lines will not be connected.

Additional Information

Certain SMUs have a feature called Sense Lead Error Detection which will cause an error to be thrown if the sense leads are connected incorrectly, but this will not cause an error if the leads are left unconnected.

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