I have been trying to connect a Standard Horizon chart plotter to a Cetrek 727 autopilot. The Cetrek works fine using the compass option and while it registers a data input ( NMEA 0183 ) from the chart plotter it comes up with an error message and beep which needs a shutdown to stop it and restart.
I have checked that the required NMEA sentences are there and that the earth is separate from the NMEA -ve.
Does anyone have experience of this connection?