12V Excitation Voltage with a NI-9218 for Bridge Based Senors

Updated May 3, 2018

Reported In

Hardware

  • NI-9218
  • NI-9237

Issue Details

Within NI MAX the only excitation voltage values I am able to use are 2V and 3.3V for my full-bridge sensor but my sensor requires 12V, is it possible to provide a 12V excitation voltage with the NI-9218?

Solution

When using the NI-9218 within a bridge configuration you will only be able to source either 2V or 3.3V through the module due to power output limitations of the device. If you require a higher voltage to excite your sensor then you will need to power the sensor with an external power supply that is capable of the required voltage and tie the power supply directly to the excitation pins of the sensor. 

Additional Information

The NI-9218 is capable of providing 2V or 3.3V when internally sourced but the excitation voltage provided is determined upon the load resistance of the sensor that you are using. To learn more about the scaling of load resistance versus internal excitation voltage for various types of bridge completions (full, half, quarter) please reference the NI-9218 Getting Started Guide

This is only the case for bridge measurements; if you would like to provide 12V excitation through the module when running a standard analog input task please reference the Voltage and Current Measurements with a Powered Sensor using the NI-9218 and NI-DAQmx knowledge base article. 

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