Garmin GNX 120 7_inch Istruzione Sull'Installazione

The marine instrument connects to power and to data sources 

through a NMEA 2000 network. In addition, the marine 

instrument can connect to a NMEA 0183 data source using a 

data cable (not included).

If you have an existing NMEA 2000 network on your boat, it 

should already be connected to power. Do not connect the 

included NMEA 2000 power cable to an existing NMEA 2000 

network, because only one power source should be connected 

to a NMEA 2000 network.
If you are installing the included NMEA 2000 power cable, you 

must connect it to the boat ignition switch or through another in-

line switch. NMEA 2000 devices will drain your battery if the 

NMEA 2000 power cable is connected to the battery directly.

The marine instrument connects to a NMEA 2000 network on 

your boat using the port labeled NMEA 2000. The NMEA 2000 

network provides power to the marine instrument and data from 

NMEA 2000-compatible devices such as a wind sensor. The 

included NMEA 2000 cables and connectors allow you to either 

connect the device to your existing NMEA 2000 network or 

create a basic NMEA 2000 network if needed.
If you are unfamiliar with NMEA 2000, you should read the 

“NMEA 2000 Network Fundamentals” chapter of the Technical 

Reference for NMEA 2000 Products. To download the 

reference, click the “Manuals” link on the product page for your 

device at 

À

Wind sensor

Á

Marine instrument

Â

Ignition or in-line switch

Ã

NMEA 2000 power cable

Ä

NMEA 2000 drop cable

Å

12 Vdc power source

Æ

NMEA 2000 terminator or backbone cable

Ç

NMEA 2000 T-connector

È

NMEA 2000 terminator or backbone cable

• The marine instrument can receive NMEA 0183 data from 

one device using a NMEA data cable (not included), but it 

cannot transmit data from the NMEA 0183 device to the 

NMEA 2000 network.

• If are replacing a legacy Garmin marine instrument that 

currently uses a NMEA data cable, you do not need to 

purchase a new data cable, but you might need to replace 

the quarter-turn locking ring with a threaded locking ring. See 

your local Garmin dealer or 

 for more 

information.

• The installation instructions provided with your NMEA 0183 

compatible device should contain the information you need 

to identify the transmitting (Tx) A (+) and B (-) wires.

• When connecting NMEA 0183 devices with two transmitting 

wires, it is not necessary for the NMEA 2000 bus and the 

NMEA 0183 device to connect to a common ground.

• When connecting a NMEA 0183 device with only one 

transmitting (Tx) wire, the NMEA 2000 bus and the NMEA 

0183 device must connect to a common ground.

• For extended runs, you should use at least 0.33 mm

2 

(22 AWG) wire.

• You must solder and seal all connections with heat-shrink 

tubing.

Red

A red wire is present only on some variations of the data 
cable, and should not be connected.

Black

Accessory (-). This wire is used only when connecting the 
marine instrument to a Garmin HVS GPS antenna.

Yellow

Accessory (+). This wire is used only when connecting the 
marine instrument to a Garmin HVS GPS antenna.

Blue

Tx/A (+). This wire is used only when connecting the 
marine instrument to a Garmin HVS GPS antenna.

White

Tx/B (-). This wire is used only when connecting the 
marine instrument to a Garmin HVS GPS antenna.

2