data acquisition question

[peni]

Iam using a pci6040e card to acquire data from lvdt load cells and pressure cells and also to control an Airbox interface box...I have managed to control the Airbox interface box but when I acquire data from the channels mapped to the particular lvdt or load cell or pressure cell, the readings tend to keep counting and does not come to a set value.,,even when nothing is connected it still tends to count when it is suppose to read zero..does anyone have any clues on how to go by getting these readings to be steady???

[Henrik_Volkers]

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@peni wrote:

[...]

 the readings tend to keep counting and does not come to a set value.,,even when nothing is connected it still tends to count when it is suppose to read zero..does anyone have any clues on how to go by getting these readings to be steady???

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The key word might be BIAS CURRENT

If nothing is connected you can read every possible value. You should get values close to zero if you short wire your inputs to ground.

Read in the manual about bias currents and how to handle it.