I have added Sea Angel's wiring diagram for the NEMA 183 interface application on Sea Angel's page 3 pixs. Sorry I have not mastered how to attach it here. 
The Raymarine C80, NAVMA F3100, Garmin 2006c and ICOM 502A are wired according to the NEMA 183. I have layed out a data transfer switch which should allow the WPTS of the GARMIN to be transferred to the C80; else, in the normal position, datas are fed through direct paths. This hookup has worked great for the past 2 years.
ICOM 502 output feeds the Garmin 2006c and the C80.
Garmin 2006c output feeds the ICOM502A and the NANMAN F3100
Both the C80 and the Garmin 2006c have their own GPS antennas.
Any further suggestions are always encouraged.
The Raymarine C80, NAVMA F3100, Garmin 2006c and ICOM 502A are wired according to the NEMA 183. I have layed out a data transfer switch which should allow the WPTS of the GARMIN to be transferred to the C80; else, in the normal position, datas are fed through direct paths. This hookup has worked great for the past 2 years.
ICOM 502 output feeds the Garmin 2006c and the C80.
Garmin 2006c output feeds the ICOM502A and the NANMAN F3100
Both the C80 and the Garmin 2006c have their own GPS antennas.
Any further suggestions are always encouraged.