How to Increase Precision on Analog Input DAQ Device?

Updated Oct 19, 2018

Reported In

Hardware

  • Multifunction I/O Device
  • C Series Multifunction I/O Module

Software

  • Measurement & Automation Explorer (MAX)
  • LabVIEW

Driver

  • NI-DAQmx

Issue Details

I want more precision on my DAQ device. Can I use a smaller voltage range to get more precision with my analog input?

Solution


This is usually possible to do, but sometimes only using a differential task. You should check the datasheet to see what is listed under Input Range to determine if your device supports this. For example, if you look at the USB 6009 Manual, you see:
 

Thus, if you set your voltage range to be -2.5 V to +2.5 V, you will have the full 14-bit-precision with the smaller range, and thus increased precision. This can be done in NI MAX or using the DAQ Assistant by changing the Signal Input Range as shown below:
 

In LabVIEW, wiring in new values to the Minimum Value and Maximum Value input terminals of the DAQmx Create Channel VI will accomplish the same.

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