Using Pull-Down Resistors for Analog Inputs

Updated Feb 16, 2021

Environment

Software

  • LabVIEW

Driver

  • NI-DAQmx

When handling open or disconnected channels, one option to control the value being read is to use a pull-down resistor.

To pull your output to zero, you can try adding a pull-down resistor between your input terminal and ground. While your input is connected, the current will go into the device if it has a lower resistance than the pull-down resistor. If you do not have your input wires attached, the input will read in the value of ground through the resistor. A 10k ohm resistor is recommended. See related links for more information on pull-down resistors.
 

Additional Information

  • Adding a resistor may have an impact on your analog input readings since they will change the load going to the ADC. If you add a pull-down resistor, check your readings after to make sure that it has not affected them.
  • It's always possible to create a software filter or programmatic "conditioning stage". Generally, an abrupt change of the voltage will mean that the load was disconnected. Make sure you test this before deploying the application.