NI DMM Reads a Negative Resistance Measurement

Updated Jan 6, 2020

Reported In

Hardware

  • PXI-407X

Issue Details

When I use my NI DMM to take a resistance measurement, the displayed value is in negative Ohms. 

Solution

This issue can be caused by different factors. Follow the troubleshooting steps below to narrow down the cause and resolve the issue.
 

Troubleshoot Hardware Set Up

  1. Short the DMM input and use InstrumentStudio to measure the resistance. 
  2. Test the DMM against a known resistance with minimal cabling. Use InstrumentStudio to measure the resistance.
    1. Select the measurement range closest to the target measurement if you know the signal range you’re trying to measure. Otherwise, select Auto. 
    2. Make sure your hardware is wired and connected correctly. When testing with your DUT, make sure you are using 2- or 4-wire configurations appropriately:
  • If the target measurement is less than 100 kOhm, use 4-wire
  • If the target measurement is more than 100 kOhm, use 2-wire.   
  1. Make sure you’re properly taking a resistance measurement by referring to Resistance Measurements.  
 
  1. Repeat the steps above with your DUT. 
  2. If all steps complete as expected, continue to the section below. If you’re still experiencing issues, contact NI Support.
 

Troubleshoot Software Set Up

  1. Test with the niDMM Measure Resistance.vi shipping example. The example can be found in LabVIEW Help >> Find Examples >> Hardware Input and Output >> Modular Instruments >> NI-DMM (Digital Multimeters). Use the measurement range closest to the target measurement to increase the resolution and decrease the effect of noise. 
  2. Test with your application. 
  • Probe the output of the niDMM Read function to make sure it is outputting the value that you’re expecting. 
  • Use debugging tools to troubleshoot the rest of your application.  
 
  1. If you’re still experiencing issues, contact NI Support.

Additional Information

To get readings that are within specification, allow instruments sufficient warm-up time to prevent offsets. Refer to your DMM’s specification sheet for the recommended warm-up time. For more information about environment considerations, refer to NI-DMM Help: Environment

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