Garmin GNX 21, Owner'S Manual

1

Select 

 > 

EDIT CURRENT PAGE

 > 

CHANGE LAYOUT

.

2

Select the number of instrument screens to view at the same 

time.

3

Select a category.

4

Select an instrument.

5

If necessary, select a data style.

6

Select 

DONE

.

Adding an Instrument Page

You can create a custom page. You can add up to three 

instruments from instrument collections to display on a custom 

page.

1

Select 

 > 

ADD/REMOVE PAGE

 > 

ADD PAGE

.

2

Select 

ONE FUNCTION

, 

TWO FUNCTION

, or 

THREE 

FUNCTION

.

3

Select an instrument page collection.

4

Select a number.

5

If necessary, select an empty function.

6

Select 

 or   to scroll through the instrument pages.

7

Select an instrument page to add.

Removing an Instrument Page

1

Select the instrument page to remove.

2

Select 

 > 

ADD/REMOVE PAGE

 > 

REMOVE PAGE

.

3

Select 

YES

.

Device Configuration

Resolving a Combined Network

When the device is turned on, it can detect when it has been 

synchronized with instruments on another network. This can 

happen if the device has previously been installed on another 

vessel and synchronized with instruments on the other vessel's 

network. If the settings are not restored to the factory default 

values (

Restoring Profiles to their Default Settings

), the device 

detects a conflict that must be resolved.

1

Select 

 > 

SETUP

 > 

COMBINED NETWORKS 

DETECTED

.

2

Select an option:
• To synchronize existing instruments on the network to the 

device, select 

NO

.

• To synchronize the device to existing instruments on the 

network, select 

YES

.

System Settings

Select 

 > 

SETUP

 > 

SYSTEM

.

UNITS

: Sets the units of measure.

HEADING

: Sets the reference and the variance used in 

calculating heading information.

BEEPER

: Sets when audible sounds are used.

GPS POSITION

: Sets the position format and the map datum. 

The map datum is dependent on the position format.

AUTO POWER

: Enables the device to turn on automatically 

when the NMEA network turns on.

LANGUAGE

: Sets the on-screen language.

OPERATING MODE

: Displays a demonstration of device 

features.

TIME

: Sets the time format, time zone, and daylight savings 

time for your location.

SYSTEM INFORMATION

: Displays software information.

FACTORY DEFAULT

: Resets the device to factory defaults.

Selecting the Heading Type

1

Select 

 > 

SETUP

 > 

SYSTEM

 > 

HEADING

.

2

Select 

NORTH REFERENCE

.

3

Select an option:
• To automatically set the magnetic declination for your 

GPS position, select 

MAGNETIC

.

• To set true north as the heading reference, select 

TRUE

.

• To set grid north as the heading reference (000°), select 

GRID

.

Configuring the Beeper

1

Select 

 > 

SETUP

 > 

SYSTEM

 > 

BEEPER

.

2

Select an option:
• To turn off the beeper, select 

OFF

.

• To set the beeper to sound only when alarms are 

triggered, select 

ALARMS ONLY

.

• To set the beeper to sound when the keys are pressed 

and alarms are triggered, select 

ON (KEYS AND 

ALARMS)

.

Configuring the Position Format

NOTE: 

Do not change the position format or the map datum 

unless you are using a map or chart that specifies a different 

position format.

1

Select 

 > 

SETUP

 > 

SYSTEM

 > 

GPS POSITION

.

2

Select an option:
• To change the position format in which a reading appears, 

select 

POSITION FORMAT

.

• To change the coordinate system on which the map is 

structured, select 

MAP DATUM

.

Configuring Data Sources

Instruments that are connected to your device and provide data, 

such as wind sensors or speed sensors, can be configured 

through your device. Refer to your instruments' owner's 

manuals for more information.

1

Select 

 > 

SETUP

 > 

DATA SOURCES

.

2

Select a data source and configure it.

3

Select your instrument.

4

Select a source and configure.

Display Settings

Select 

 > 

SETUP

 > 

DISPLAY

.

COLOR

: Sets the screen color.

BACKLIGHT

: Sets the backlight brightness.

NETWORK SHARING

: Shares color and backlight settings with 

devices across the NMEA 2000 or NMEA 0183 network.

Viewing and Editing NMEA Settings

You can view information about NMEA or NMEA 2000 device 

and change device-specific options.

1

Select 

.

2

Select 

SETUP

.

3

Select 

NMEA 0183

 or 

NMEA 2000 DEVICES

.

4

If necessary, select an option:
• To view information about the device, such as the 

software version and the serial number, select 

DEVICE 

LIST

.

• To change the label of a device, select 

LABEL DEVICES

.

2

Device Configuration