To the OC32 to configure and update you must connect it to a PC. The best way to do that is via the RS485 link available on the OC32. The U485 is a compact module, the size of a USB memory stick that lets you easily add a RS485 interface to a PC with USB interface. The U485 simply works as a "virtual COM port", so just like "normal" USB-serial converters.
The big advantage of this method is that the connection is very robust (RS485 is designed for industrial applications), you can cover large distances (theoretically up to 1200 meters), and you need only one U485 to link multiple OC32 (with the current software up to 16 pieces)
If you purchase the U485 along with your OC32 he is hardly more expensive than a "normal" USB-serial converter.