PGM-WIN software will recognize PC  serial com ports 1 through 4 for the operating software and the firmware upgrader.

If the user has a USB to Serial port adapter they will need to configure the adapter to an available serial com port between 1 and 4 in windows control panel / system / hardware devices.

Windows will sometimes assign a USB to Serial adapter or a PCIMIA adapter card to an available com port higher than serial com port 4, if this is the case the user will need to determine if an available com port between 1 and 4 is available.

The standard PC serial com port settings for Matrix +3 use are as follows, screen shot below from Windows / Control Panel / System / Hardware settings / Com port port settings: