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Slight negative offset with PCI-6250 set at 0-10 V !

Hello,
 
I have a problem with my PCI-6250. I have created an AI voltage channel with Vmin set at 0V and Vmax set at 10V. But when the acquisition is performed, some values are slightly negative ! I don't understand at all. Input terminal configuration is set to default, should I set this input to differential or anything else ? (the system is as follow : there's a sensor and a charge amplifier, then my PCI-6250)
 
Thank you in advance for your help,
 
Julien
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Hey Julien

 

Did you use the example VI provided by LabVIEW? Did you modify it? If you did could you please post it? This error might be caused by the referencement type (Differential, referenced, non-referenced) It depends on how is your system build...

Here is a link (and an other) that may guide you through this choice.

 

Regards

Richard Keromen

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For PCI-6250 the input terminal is configured to differential by default (ai0 with ai8), which is not suitable for my system. By changing it to NRSE, il should work properly. Thank you very much for your help !

Best,

Julien

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Also note that when you specify a voltage range, DAQmx coerces this range to the most appropriate range available on the device. For the PCI-6250 in this case, DAQmx is using the +/- 10V range in this case, so negative voltage measurements can be returned.
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Thank you very much for this information. It can be useful to know that.

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