Jump to content

As of July 17, 2015, the LabJack forums here at forums.labjack.com are shut down. New registrations, topics, and replies are disabled. All forums are in a read-only state for archive purposes.

Please visit our current forums at labjack.com/forums to view and make new posts. To post on the current forums, use your labjack.com login account. Your old LabJack forums login credentials have been retired. There are no longer separate logins for labjack.com and LabJack forums.

U12 Offset calibration

  • Please log in to reply
1 reply to this topic

#1 Guest_James Dorsey_*

Guest_James Dorsey_*
  • Guests

Posted 12 August 2005 - 08:00 AM

I am trying to measure a Diff signal in the range of 0 to 25mV. Even with the AI0 & AI1 shorted together I get ~ 2mv offset. I have verified using a Fluke 87 the input is indeed 0 but the device is reporting 2mv. I have selected the 1V range for gain. Is there a way to "Calibrate" the Zero Offset out of the LabJack U12?

#2 LabJack Support

LabJack Support
  • Admin
  • 8677 posts

Posted 12 August 2005 - 08:12 AM

That is one of the great things about PC-based data acquisition. You just enter your 2 mV offset in software to subtract it off. You could do the re-calibration procedure described in Section 3.7 of the U12 User's Guide, but I would not bother. The voltage resolution at the +/-1 volt range is 2/4096 = 0.5 mV/count, so your 2 mV of offset is only 4 counts and not unusual. Also note that each channel on the U12 has individual signal conditioning, so each channel might have a different offset. Also also note that since the resolution is 0.5 mV/count, you will only get about 50 counts across your entire 25 mV range.

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users