PXIe-4331 Vch input impedance?

[tbilir]

What is the input impedance of the Vch measurement amplifier?

I am interested in measuring a very high (100M-ohm+) resistance full bridge and I'm concerned a typical 1M-ohm input impedance will load the bridge but I can't find the specification in the documentation anywhere.

[Chase.E]

From what I can see, NI does not specify the input resistance of the 4331.

What Voltage range are these measurements going to be in?

[tbilir]

I prefer the lowest voltage, so that my digitizer resolution is as high as possible.  But one thing I saw which I thought was odd was the Vex "minimum current" at 29mA, which suggested my resistances are too high to work anyway...

[Chase.E]

What resistance values are you using? Do you already have a 4331 on hand you are looking to use, or are you spec'ing a system?

[tbilir]

I'm intending to use 1M-ohm resistances.  And I have ordered a system, but may need to return it if it is not suitable.

[Chase.E]

I think this question would be better answered by a service request. Could you create one from your online account or call in so we can work a bit more efficently?