Voltage and Current Measurements with an Externally or Internally Powered Sensor Using the NI 9218 and NI-DAQmx

Updated Feb 18, 2019

Reported In

Hardware

  • NI-9218

Driver

  • NI-DAQmx

Issue Details

When connected to an external power supply, the NI 9218 is capable of delivering 12 Volts of excitation to a sensor and then measuring the voltage or current output of the sensor. How do I configure my NI 9218 using LabVIEW and NI-DAQmx to take these measurements?

Solution

The implementations for current and voltage measurements are slightly different and require different adapters for the NI 9218 as described below:

1. Current Measurement with a Powered Sensor

To perform a current measurement you must use the NI 9983D/L/F Current Shunt Adapter and enable the DAQmx Channel Property Nodes AI.Excit.Src and AI.Excit.Val as shown below:


2. Voltage Measurements with a Powered Sensor

To perform a voltage measurement with internal excitation you must select the +/-65 mV or +/-16 V measurement range/mode and use the NI 9982D Screw Terminal Adapter. You have the option of utilizing the DAQmx Create Channel (AI Custom Voltage with Excitation) VI or a property node in conjunction with the DAQmx Create Channel (AI Voltage) VI as shown below: