Wiring a NMEA 0183 Compatible Device to a Serial Port

The NMEA 0183 output from a chartplotter can be tested by connecting to a DB-9 serial connector. By wiring in the proper NMEA 0183 wires from the Garmin device, a computer with a DB-9 serial port can verify the information that is coming from the device. A DB-9 serial connector can be purchased from many electronics stores.

Please follow the below instructions to connect the DB-9 connector to the power cable of the device:

1. Connect the NMEA Out + wire from the chartplotter/sounder to Pin 2 of the DB-9 connector
2. Connect the NMEA In + wire from the chartplotter/sounder to Pin 3 of the DB-9 connector
   • If the chartplotter/sounder only has one NMEA In or NMEA Out wire, those wires will be positive (+)
3. Connect the NMEA Out - (if applicable), the NMEA In - (if applicable) and the chartplotter/sounder Ground to Pin 5 of the DB-9 connector and to the negative side of a 12-volt power source
   • If the Red (Positive Power)  and Black (Ground)  wires of the chartplotter/sounder are not connected to a 12-volt power source, this test will not work properly
4. Connect the completed DB-9 connection to the computer
5. Power on the chartplotter/sounder

Once the wiring is completed, a computer program can be used to verify the information being sent from the Garmin device. Once such program that was available on Windows XP was HyperTerminal. For information on how to use HyperTerminal, please see Related Content.