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

Updated May 5, 2025

Reported In

Hardware

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

Software

Measurement & Automation Explorer (MAX)

Driver

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."

Solution

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 and CompactDAQ or CompactRIO Hardware Compatibility with LabVIEW
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.

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