All the intstruments connect through it's CPU.

http://mediabase.edbasa.com/kunder/navico/display_pages.php?object_id=navidoc~73224135&pages_dir=navidoc%2Fj2009%2Fm08%2Ft14%2F0002468_2 pages

http://www.raymarine.com/default.aspx?Page=1009&Section=2

If you tried to connect through NEMA 2000 (or NEMA 0183), but it's not necessarily full function and it's slower.

You may be getting or passing information to other non-related systems (like a GPS or other information, for example).

You can see this especially with trying to connect a electronic compass that provides relative accelerations for MARPA to a radar. If you try to connect in different manufacturers, you need to be very careful (if indeed it work at all).

Our Furuno 3D radar system really only wants to see a compatible Furuno compass for MARPA.

YES, NEMA 2000 is a platform that may eventually easily connect a variety of "open systems" -- but so far, I think it takes a lot special expertise to avoid connecting those devices successfully. It's certainly not seemless.