connecting nitrate ISE to NI DAQ 6024E

[Yeon]

Hi, I've tried to connect nitrate ion selective electrode output leads to NI DAQ6024E analog input. The problem is that I measure sine-wave like huge voltage swing around DC value (about 900mV amplitude). When I try this ISE with digital multimeter or other datalogger (e.g. Hoboware) they worked fine and I didn't see this huge swing. I've tried single-ended or differential input for input configuration, but they are all the same. I also checked my DAQ with DC signals (like 1.5V battery) and it worked well.
So, I guess I need to change some kind of setting in my DAQ ?
The averaged value of the sine-wave voltage was similar value to the one from multimeter.

Does anybody have any idea why this large voltage swing is observed ? Thank you so much.

[Jesse_O]

Hello Yeon,

From the information that you provided below, it sounds like you have a grounding/connection problem. Please see the field wiring diagram developer zone article. If you look at table 1 you will see how to connect your signal (including how to ground the system). Once you verify and connect your signal properly, the best place to test your setup is within Measurement and Automation Explorer (MAX) using a test panel for your device.

Regards,

Jesse O.
Applications Engineering
National Instruments