Originally Posted by transmitterdan
Yes. OpenCPN allows a serial port to be designated as an “output” using the options->connections settings. Then OpenCPN will send each NMEA message it receives back out that output connection. If you fit your computer with the right kind of adapter it can output NMEA data. There are RS-485 USB serial adapters in the market. Sometimes you can use an RS-232 USB adapter with some success. It depends on the MFD design. RS-232 works with probably 90% of MFDs.
For a good connection the NMEA-send connection should be galvanic isolated as required by specification.
When OpenCPN is sending
information over NMEA you should add galvanic isolation, at least if you don't want to risk failure due to electronic discharge caused by ground loops. This means just an RS232
to USB connector is not sufficient while it will work
for a few days...
If you are very conservative you will isolate each connection (both send and receive) and the computer itself (power). It's your installation
, you decide.
Main difference between a (real) RS485 and a RS232
is as far as I know the isolation.