You have two choices:
- USB plus the driver that came with the unit, (check Ray website for updates),
output - on your unit it is rs422, in this case you want a rs422 to serial
converter that works on your specific computer.
If you are not sure which cable make works on your computer, stick with ftdi and look up their website for drivers that work on your computer OS before buying
anything. Ftdi are very well documented. You will be likely on RS232R chipset. There are other chipsets too, like e.g. prolific. These seem less well documented (IMHO).
WARNING: if on nmea output, you will NOT be using a rs232
converter cable - unless you are very lucky and yours works (mine does not).
At AMEC website you will find a picture showing how, at times, rs422 can be cross-linked using rs232
cable (all the risk is yours, off course). This can be attempted when no rs422 cable available but I tried on a Simrad
unit and it did not work (with ftdi 232 cable).
Level: easy. But takes patience and experimenting.