PXIe-6341 only reading 15 bit when in RAW.

[StevenHowell_XOM]

Good morning,

I have a project where I am using a PXIe-6341 that is reading a 0-10VDC signal from an instrument. The end user only wants to take the ADC "counts" for the values, we are not scaling any of the values. 

I have the virtual channel set for Max 10, Min 0. According to everything I have read, this should put the channel into a uni-polar mode and a gain of 1. 

When we collect data, we are seeing the maximum value of 32767 for a saturated value of 10V that we expect for a specific scenario. 

We were expecting to see values from 0-65535.

I do have the channel read set for RAW 1D U16, so I should be getting unsigned numbers from 0-65535. 

Am I missing something? We dont have any values going negative in this case but it appears that the board is only acquiring data in 15 bits and not 16.

Thanks,

Steven

[Kevin_Price · Accepted solution]

A quick look at the summary spec sheet seems to only list bipolar voltage ranges.   Though a little surprising, I think the most likely explanation is that you don't get the option to spread 16 bits across the 0 to +10 volt range, you're stuck spreading them across the -10 to +10 range.  Hence only 15 bits for the positive side.

-Kevin P

[StevenHowell_XOM]

Kevin,

Thank you for taking the time to answer my question. I looked all through the NI website and I was not able to find the answer to this simple question.