Error -201251 When I Try to Add a Device in NI MAX

Updated Apr 6, 2023

Reported In


  • cDAQ-9189
  • cDAQ-9181
  • cDAQ-9184
  • cDAQ-9188
  • cDAQ-9185
  • cDAQ-9191


  • Measurement & Automation Explorer (MAX)


  • NI-DAQmx

Issue Details

When trying to "Add Device" in MAX, I get error -201251 with the following message:

"Add device has failed. Device could not be found on the network. This usually indicates an incorrect hostname or a DNS failure."


This message usually comes up when the firewall or antivirus is blocking the device. In the Troubleshooting Network cDAQ Connectivity Issues  you can find the TCP and UDP ports you might need to open in order to remove this error. If you are allowed to turn the firewall/antivirus off, that should be faster for testing.

You can also:
  • Check the C Series Module Compatibility Chart
  • Make sure that both the cDAQ Chassis and the C Series module is supported by your NI-DAQmx version. You can find this information in the readme file of each version of the driver.