PCI-6024E DAQmx reading a negative voltage on a battery

[robojeff]

I have this VI that is occasionally reporting a measured negative voltage of a battery
and I am not sure why because tis value should never be a negative value...

Below is a screen shot with a couple of probes and I would appreciate any ideas on how
to correct this issue

thanks

 

[Alexander_Sobolev]

Is it within precision? Hard to see on this low resolution picture, but looks like you have -4 mV value with +/- 10 V range. 12 bit board, you can not expect better precision.

If your battery is 5 V and you are getting 0, then it is connection issue.

Can you show graph of the points without averaging? Is it always 0, or oscillating between +/-5 so that averages to 0?

[aputman]

I used to have good eyes but they are not working so well as I near 40. 

[robojeff]

Sorry for the delay in responding as I have been trying everything to isolate this but it no longer

looks like a Labview issue and more of a hardware issue, and here is why I think that this is so...

I decided to isolate everything by only connecting the PCI-6024E that is inside my PC to a NI SCB-68A breakout box.

I then connected a jumper wire from the SCB-68A chassis ground lug to pin 68 (AI 0) as this is the line that I am measuring

with my application and hardware test fixture and all measured values are Negative which is why my application is failing.

Below is a screen shot of the measurements

Because this now appears to be a hardware problem, which forum should I post this issue in?

Thanks

[Alexander_Sobolev]

Negative is not a problem. You are getting 0 within board precision. 

[JÞB]

I would look at the SCB Switch settings