NMEA0183 input on WestMarine VHFDSC500 -- wiring to NMEA +/- Outputs on C80 chart plotter
I am buying an old'ish boat that has a Raymarine C80 chartplotter and a West Marine VHF DSC500 radio. The radio is currently not connected to a GPS source, so if I used DSC I'd need to manually enter coordinates; seems like that would be missing the point. I want to connect the NMEA Out (-ve)/Out(+ve) from the chartplotter to the NMEA input on the radio but I'm a little unclear on the wiring because the signal naming conventions vary between the devices.
The C80's NMEA connector is 5-pin, shown here
The DSC500 is an 8-pin connector but it doesn't have +/- NMEA inputs like newer radios, although the user manual says it's a NMEA0183 compatible interface. It looks like this:
What seems obvious (but possibly wrong haha) is that I would wire C80 YELLOW (Output(+ve)) to DSC500 Pin 4 GRN "GPS Data In".
Wiring the C80 BROWN Output (-ve) to the DSC500 is less obvious. I propose I need to wire it to the External Speaker (-) GND (BLK).
Would this proposed wiring be correct? If not, any insights you can provide would be appreciated.