ni daq 6255 wrong voltage readings

[colshan]

Hi,

I have my daq configured to have 14 differential channels.

The first two channels should be reading a voltage drop of .03 volts, but they are reading .3 volts.

All of the others are reading correctly.

Yesterday I had the same problem and was able to change the sampling rate and get it to read at the right level.

Today that is not working, so I think it was a coincidence.

I have checked the voltage drop with a multimeter.

Any help would be appreciated, it seems very odd that the error is exactly 10X.

Also, I am using labview signal express to read the voltages and I have checked (and rechecked) the connection diagram.

The setup is actually quite simple.

thanks

C

[CWolf]

C,

I would recommend taking Signal Express out of the picture by instead using Test Panels in MAX to read the values.  Are the incorrect readings only happening on the first 2 channels?  (As in, if you read the same signal in through all the channels, the first 2 show .3 and all the rest show .03, correct?)  What do these channels read if you hook up .5 V or 1 V to them?  If these two specific channels are still reading incorrect values in Test Panels, regardless of the voltage that is being wired into them, then it is possible that the device is damaged.  

-Christina