I assume that you used a Simnet to
NMEA 2000 adapter cable to connect your new Precision 9
Compass to the Simnet
network so it could provide heading information to your
autopilot.
If you have another of those
cables and a spare socket on your Simnet
network, you can connect the Vesper XB8000 into the Simnet network, and it will convert the
NMEA 2000 PGN 127250 Heading message into the
NMEA 183 HDG sentence which will get the heading information into
OpenCPN in the same way you are getting
GPS position information from the XB8000 into
OpenCPN. The Vesper XB8000 performs a limited number of
NMEA 2000 to NMEA 183 conversions, of which heading is one of those.
No need to splice
cables or bastardise anything.
The one thing I do not understand is the role of the AT10. I'm guessing it was previously connected to your Simnet network and was used to get heading data from the Simnet network, convert it to NMEA 183 and I'm guessing to provide heading data to OpenCPN. Not sure why you needed it when the RC42 has both Simnet and NMEA 183 connections.
Or do you have an AT10HD which is the "high speed", "reverse" version of the AT10 and is designed to get heading data from a 10Hz NMEA 183
compass, convert and transmit it onto the Simnet network, usually for
consumption by a RI10
Radar Interface in order for it to provide MARPA and
Radar Overlay support on
Simrad displays.
As you had mentioned a Halo radar, not sure why the RI10 is necessary as I thought they were only used with the older
broadband radars ?