1. Open the Device Manager. You can use the shortcut key Win+R to open the running dialog box, enter "devmgmt.msc" and press enter to open the device manager.
2. Expand the port (COM and LPT) nodes. You can find the node in the left panel of Device Manager and click to expand it.
3. Check the serial port (COM) list. Under the "Ports (COM and LPT)" node, you should be able to see all serial devices recognized by the system and their corresponding COM port numbers. If there are no serial devices on your computer, this list may be empty.
Note: If the serial driver is not installed correctly or is in use, you may see a yellow exclamation point or question mark. If this happens, you need to install or update the serial port driver, or stop using the application that occupies the serial port.