I am attempting to monitor a hand full of sensors that output resistance. I do not seem to be getting the expected results. I am sure it is my lack of knowledge on the USB-6008 unit so I thought I would ask. To make this as simple as possible Ill uses the light sensor (photocell) as an example. In this I only need to read the resistance across the photocell. First I tried connecting the photocell the way the diagram in VI Logger Tasks --> My Task1 --> Edit Task -->Connection Diagram shows (PIN 2 --> Pin 3) This gave me readings all over the place! I then tried connecting it the way I though it should connect (Pin 2 --> GND) again nothing. At this point I went to the test panel in the Ni-DAQmx software I changed the setting for AI0 to single-ended (RSE) and tested it. To cut this short, I found that in the Test Panel with AI0 set to RSE and the sensor hooked up between Pin 2 and Pin 32 (+5v) I get a perfect reading! When I am in the software it does not work. Well it does work, if I put the photocell between pins 2 and 3 then run a 5v line from pin 32 to the lead from pin 2. It would appear that I need to tell the unit that AI0 is single-ended; I just can not find a place to do that. The Preferences selection in Devices and Interfaces --> NI-DAQmx devices --> NI USB-6008 is grayed out. So what am I doing wrong?

Multifunction DAQ

Analog single-ended setup with USB-6008

Author

AnalogKid,

Hmm, are you a Rush fan ? 🙂

Ok, that was my mistake, it is pin 31 that is the 5v line. I was using pin 31 but when I made the post I was doing it from memory.

Lets keep this simple, only consider the photocell. The others were examples and any issues I may have with them, well Ill cross that bridge when I come to it. I can think of lots of things that I would need to read the resistance on.

What I am trying to do is to measure the resistance across a photocell in RSE mode. AI0 would be (PhotoCell) pin2 to ground (pin1) with a lead to the 5v line pin31.