Non-zero voltage reading with AIN1 short to ground. | LabJack
 

Non-zero voltage reading with AIN1 short to ground.

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PKlammer
PKlammer's picture
Non-zero voltage reading with AIN1 short to ground.

With a short jumper wire firmly in screw terminals AIN1 and GND (in same block of 4 terminals), I am getting constant non-zero readings in LJLogUD, e.g. 0.000021, flickering +/- 2 or 3 in last decimal position. Do I need to calibrate or what?

As workaround I have applied an offset of the nominal minimum 0.000017 in formula, to avoid negative evaluations.

 

 

LabJack Support
LabJack Support's picture
The accuracy spec on the 0.1V

The accuracy spec on the 0.1V range is 20uV, so you are close to the limit but does not seem alarmingly off.

https://labjack.com/support/datasheets/u6/appendix-a

When dealing with a handful of microvolts, and few things that can make a difference:

1.  Different GND terminals.  To eliminate this factor, jumper both AIN0 and AIN1 to GND and do a differential reading of AIN0 (+ch=0, -ch=1).

2.  Temperature of the U6.  Stabilize device at room temperature to match calibration temperature.

3.  Other connections to the U6.  Remove all connections except USB and your 1 or 2 jumper wires.