The Classic C + E Series plotters had just one NMEA0183 Port to connect the Sonar Server to – click here for wiring details.
The port must output and input data at the same baud rate, so if you already have an AIS connected to this port then you will need to reconfigure the Sonar Server baud rate to 38400 baud, which is detailed in a Tech Note that can be downloaded by clicking here.