20mV variation between Labjack Matlab and Multimeter

2 posts / 0 new

Wed, 11/20/2019 - 09:43

daqnewbie

Hello,

I am seeing that there is a 20mV difference between my multimeter readings and my labjack readings. I get 51mV out of mulimeter and 74mV when I look at it with Matlab through the labjack. I have a U3-HV and I am reading the measurements through DAC0 and AIN0. Is this to be expected? Do the higher voltage channels have more variation? Which are the higher voltage channels?

Thanks for your help!

Wed, 11/20/2019 - 10:39

LabJack Support

Hello,

The 20mV error you are seeing is within the full scale accuracy spec for the HV lines. The low voltage channels do have less error due to the smaller voltage range. Please see the absolute accuracy ratings and note 8 on the U3 datasheet for more information regarding AIN accuracy: https://labjack.com/support/datasheets/u3/appendix-a .

AIN0-3 are the high voltage channels (note that these are just flexible IO channels that are permanently fixed as HV analog inputs). You can configure the other flexible IO channels to be analog inputs and they will act as low voltage AIN lines: https://labjack.com/support/datasheets/u3/hardware-description/fio .