11-01-2010 02:31 PM
Hi,
I am attempting to read an analog voltage using a USB-6229 DAQ.
I have a voltage at ~6.7V that I read with a DMM (nothing connected to the DAQ).
When I try to read that same signal through AI0 (or AI1) and AIGND I read a steady 10.6V using Measurement & Automation Explorer.
When I have this signal connected to AI0/AIGND and read the same signal using the DMM, the DMM reading jumps to ~13V.
I assume there is some sort of grounding issue here somewhere. Can anyone help me diagnose this problem I'm seeing?
Thank you,
Seth
11-02-2010 03:33 PM
Hi Seth,
What is the signal source that you are reading? Is this a grounded signal source (like a power supply) or is this a floating source (like a battery)? How do you have your signal wired? Are you reading single ended or differential in MAX? The document below is a good reference for signal connections (take a look at Table 1):
Field Wiring and Noise Considerations