The Lowrance Elite 4 Fish Finder can be configured to have one differential NMEA0183 Port (RS422 mode) or two common ground NMEA0183 Ports (RS232 Mode). You can connect the Sonar Server in either mode – 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.