Additional Information
These solutions also help resolve
Error 37: Device Not Found that occurs when using Serial Compatibility VIs. These VIs have been deprecated so the error is only mentioned here as a note. If receiving the same error message in NI MAX, or for additional troubleshooting steps, please refer to the article titled
COM Port in MAX Shows Exclamation Point.
If you are using CompactRIO, this is caused by enabling Console Out. Please check the startup setting or dip switch of cRIO.
Finally, this issue could be caused by plugging two different devices into the same COM port sequentially. The VISA resource could be trying to reference the last device, and be still in use.