NI-Serial did not recognize every serial interface. There are several reasons why you might encounter this problem:

The serial interface is not properly installed

Refer to the Serial Hardware and Software Help to verify that your serial interface is correctly installed. Rerun the NI-Serial Troubleshooter.

You ran the Troubleshooter before the Add New Hardware Wizard completed the task of adding the Plug-and-Play interface to your system.

Follow the steps in the Add New Hardware Wizard to finish adding the hardware to your system before you run the Troubleshooter. If you canceled the Add New Hardware Wizard before it completed, reboot your system and make sure the Add New Hardware Wizard completes before continuing with the Troubleshooter.

Serial USB interface not detected

The USB host controller must be working properly to use the serial interface. Refer to the Device Manager to verify that the host controller is functioning properly. If you select View devices by type, you can review the USB Host Controller properties to ensure it is correctly enabled and functioning.

Serial interface has been removed from the system

You have removed the serial interface from the system. Click on the link below to launch the Device Manager. Right-click on your computer's name in the list and select Scan for hardware changes. You may also reboot your computer to allow the operating system to detect and install your serial interface.