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Changing the Com Port Number for a USB to Serial Converter

Most laptops do not have a 9-pin serial port.  So we are forced to use USB to Serial converters or adapters for communicating with devices over RS-232.  Most older GUI software only allows the selection of the lower numbered com ports, such as COM1, COM2, COM3, and COM4.  Often, the drivers for USB adapters are configured to use COM5 and up by default.  In these cases, the GUI will not allow selecting the com port needed to communicate with the hardware device.  And the only way to solve this problem is by changing the com port number of the USB adapter driver.

1. Go to the Control Panel.

2. Click on System.

3. Click on Device Manager


4. Right-click on the USB adapter under Com Ports and click on Properties.

5. Go to the Port Settings tab and click on Advanced.


6. Select a com port number that is compatible with the GUI software.

7. Click OK.

Most laptops are such that the com port is associated with the USB adapter driver, not the physical USB port.  So the com port number will be the same for the USB adapter no matter which USB port it is plugged into.