If you have a G4 system, you only have two USB connectors and no serial ports. Avid suggests you attach a USB hub to the rear of the G4 system and use a Keyspan Twin USB-to-serial adapter (Macintosh only) for deck control.

If you have a PC system, you will most likely have at least 2 USB connections and one serial connection. If you need more than one serial connection, Avid recommends using a USB-to-serial adapter. Use the documentation that comes with the device.