If you are using Windows XP, you will need to have Service Pack 3 installed before installing the drivers for the Maestro. See below for details.
Before you connect your Maestro to a computer running Microsoft Windows, you should install its drivers:
Windows 8, Windows 7, and Windows Vista users: Your computer should now automatically install the necessary drivers when you connect a Maestro. No further action from you is required.
Windows XP users: Follow steps 5–9 for each new Maestro you connect to your computer.
If you use Windows XP and experience problems installing or using the serial port drivers, the cause of your problems might be a bug in older versions of Microsoft’s usb-to-serial driver usbser.sys. Versions of this driver prior to version 5.1.2600.2930 will not work with the Maestro. You can check what version of this driver you have by looking in the “Details” tab of the “Properties” window for usbser.sys in C:\Windows\System32\drivers. To get the fixed version of the driver, you will need to install Service Pack 3. If you do not want Service Pack 3, you can try installing Hotfix KB918365 instead, but some users have had problems with the hotfix that were resolved by upgrading to Service Pack 3. The configuration software will work even if the serial port drivers are not installed properly.
After installing the drivers, if you go to your computer’s Device Manager and expand the “Ports (COM & LPT)” list, you should see two COM ports: the Command Port and the TTL Port. In parentheses after these names, you will see the name of the port (e.g. “COM5” or “COM6”). If you expand the “Pololu USB Devices” list you should see an entry for the Maestro.
Some software will not allow connection to higher COM port numbers. If you need to change the COM port number assigned to your USB device, you can do so using the Device Manager. Bring up the properties dialog for the COM port and click the “Advanced…” button in the “Port Settings” tab. From this dialog you can change the COM port assigned to your device.