Garmin GNX 20 User manual

GNX™ 20/21 Installation Instructions
To obtain the best possible performance, install this marine
instrument according to these instructions. If you experience
difficulty during the installation, contact Garmin® Product
Support, or seek the advice of a professional installer.
This instrument communicates with NMEA 2000® sensors and
devices, and shows information such as speed, heading, and
water depth when connected to the appropriate sensors. The
instrument can also communicate with a NMEA® 0183 device
using an optional data cable.
Important Safety Information
WARNING
See the Important Safety and Product Information guide in the
product box for product warnings and other important
information.
CAUTION
Always wear safety goggles, ear protection, and a dust mask
when drilling, cutting, or sanding.
NOTICE
When drilling or cutting, always check what is on the opposite
side of the surface.
Registering Your Device
Help us better support you by completing our online registration
today.
• Keep the original sales receipt, or a photocopy, in a safe
place.
Mounting Considerations
NOTICE
This device should be mounted in a location that is not exposed
to extreme temperatures or conditions. The temperature range
for this device is listed in the product specifications. Extended
exposure to temperatures exceeding the specified temperature
range, in storage or operating conditions, may cause device
failure. Extreme-temperature-induced damage and related
consequences are not covered by the warranty.
The mounting surface must be flat to avoid damaging the device
when it is mounted.
Using the included hardware and template, you can flush mount
the device in the dashboard. If you want to mount the device
using an alternative method where it appears flat with the front
of the dashboard, you must purchase a flat-mount kit
(professional installation recommended) from your Garmin
dealer.
When selecting a mounting location, observe these
considerations.
• The mounting location should be at or below eye level to
provide optimal viewing as you operate your vessel.
• The mounting location should be at less than a 45° viewing
angle for the GNX 20 Marine Instrument with Standard LCD
and less than a 50° viewing angle for the GNX 21 Marine
Instrument with Inverted LCD. Screen color inversion occurs
when the viewing angle is greater than 30° in the 9 o'clock
direction on the GNX 20 and when the viewing angle is
greater than 60° in the 1 o'clock direction on the GNX 21.
• The mounting location should allow easy access to the keys
on the device.
• The mounting surface must be strong enough to support the
weight of the device and protect it from excessive vibration or
shock.
• To avoid interference with a magnetic compass, the device
should not be installed closer to a compass than the
compass-safe distance value listed in the product
specifications.
• The area behind the mounting surface must allow room for
the routing and connection of the cables.
Mounting the Device
NOTICE
If you are mounting the device in fiberglass, when drilling the
four pilot holes, it is recommended to use a countersink bit to
drill a clearance counterbore through only the top gel-coat layer.
This will help to avoid any cracking in the gel-coat layer when
the screws are tightened.
Stainless-steel screws may bind when screwed into fiberglass
and overtightened. Garmin recommends applying an anti-seize
lubricant to the screws before installing them.
The included template and hardware can be used to flush mount
the device in your dashboard. To mount the device so the
screen is flat with the dashboard, you must purchase a flat-
mount kit from your Garmin dealer.
1Trim the flush-mount template and ensure it will fit in the
location where you plan to mount the marine instrument.
The flush-mount template is included in the product box.
2Remove the liner from the adhesive on the back of the
template and apply it to the location where you plan to mount
the marine instrument.
3If you plan to cut the hole with a jigsaw instead of a 90 mm
(3.5 in.) hole saw, use a 10 mm (3/8 in.) drill bit to drill a pilot
hole to begin cutting the mounting surface.
4Using the jigsaw or the 90 mm (3.5 in.) hole saw, cut the
mounting surface along the inside of the dashed line
indicated on the flush-mount template.
5If necessary, use a file and sandpaper to refine the size of
the hole.
6Place the marine instrument into the cutout to confirm that
the mounting holes on the template are in the correct
locations.
7If the mounting holes are not correct, mark the correct
locations of the mounting holes.
8Remove the marine instrument from the cutout.
9Drill the 2.8 mm (7/64 in.) pilot holes.
If you are mounting the marine instrument in fiberglass, use a
countersink bit as advised in the notice.
10Remove the remainder of the template.
11Place the included gasket on the back of the device and
apply marine sealant around the gasket to prevent leakage
behind the dashboard.
12If you will not have access to the back of the device after you
mount it, connect all necessary cables to the device before
placing it into the cutout.
NOTE: To prevent corrosion of the metal contacts, cover
unused connectors with the attached weather caps.
13Place the marine instrument into the cutout.
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14Securely fasten the marine instrument to the mounting
surface using the supplied screws.
If you are mounting the marine instrument in fiberglass, use a
anti-galling lubricant as advised in the notice.
15Snap the bezel À into place.
Connection Considerations
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).
NMEA 2000 Connection Considerations
NOTICE
If you have an existing NMEA 2000 network on your boat, it
should already be connected to power. Do not connect the
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.
Item Description
ÀWind sensor
ÁMarine instrument
ÂIgnition or in-line switch
ÃNMEA 2000 power cable
ÄNMEA 2000 drop cable
Å12 Vdc power source
ÆNMEA 2000 terminator or backbone cable
ÇNMEA 2000 T-connector
ÈNMEA 2000 terminator or backbone cable
NMEA 0183 Connection Considerations
• 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 you 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.
• 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 mm2
(22 AWG) wire.
• You must solder and seal all connections with heat-shrink
tubing.
Wire Color Wire Function
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.
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Wire Color Wire Function
Brown Rx/A (+)
Green Rx/B (-)
NMEA 0183 Connection Diagrams
This diagram is an example of a connection to a standard NMEA
0183 device with two Tx wires.
Item Description
ÀMarine instrument with a NMEA data cable (not included)
Á12 Vdc power source
ÂNMEA 0183-compliant device
Item Garmin Wire
Function
Garmin Wire
Color
NMEA 0183 Device
Wire Function
ÊN/A N/A Power
ËN/A N/A Data ground
ÌRx/A (+) Brown Tx/A (+)
ÍRx/B (-) Green Tx/B (-)
This diagram is an example of a connection to a standard NMEA
0183 device with one Tx wire.
Item Description
ÀMarine instrument with a NMEA data cable (not included)
ÁNMEA 2000 network (must connect to the same ground as the
NMEA data cable)
Â12 Vdc power source
ÃNMEA 0183-compliant device
Item Garmin Wire
Function
Garmin Wire
Color
NMEA 0183 Device
Wire Function
ÊN/A N/A Power
ËN/A N/A Power ground
ÌRx/B (-) Green Data ground
ÍRx/A (+) Brown Tx
This diagram is an example of a connection to a Garmin HVS
GPS antenna.
Item Description
ÀMarine instrument with a NMEA data cable (not included)
Á12 Vdc power source
ÂGarmin HVS GPS antenna
Item Marine Instrument Wire Color Antenna Wire Color
ÊN/A Red
ËBlack Black
ÌYellow Orange
ÍBlue White
ÎWhite White/orange
ÏBrown Gray
ÐGreen White/red
Specifications
Specification Measurement
Dimensions without sun cover
(H×W×D)
110 x 115 x 30 mm (4.33 x 4.53 x
1.18 in.)
Dimensions with sun cover
(H×W×D)
115 x 120 x 35.5 mm (4.53 x 4.72 x
1.40 in.)
Weight without sun cover 247 g (8.71 oz.)
Weight with sun cover 283 g (9.98 oz.)
Temperature range From 5° to 158°F (from -15° to 70°C)
Compass-safe distance 209 mm (8.25 in.)
Material Case: fully-gasketed polycarbonate,
waterproof to IEC 60529 IPX7
standards
Lens: glass with an anti-glare finish
Power usage 2.5 W max
Unit max. voltage 32 Vdc
NMEA 2000 input voltage 9–16 Vdc
NMEA 2000 load equivalency
number (LEN)
6 (300 mA at 9 Vdc)
NMEA 2000 PGN Information
Type PGN Description
Transmit and receive 059392 ISO acknowledgment
059904 ISO request
060928 ISO address claim
126208 NMEA: Command, request, and
acknowledge group function
126464 Transmit PGN list group function
126996 Product information
Receive 126992 System time
127245 Rudder
127250 Vessel heading
127508 Battery status
128259 Speed: Water referenced
128267 Water depth
129025 Position: Rapid update
129026 COG and SOG: Rapid update
129029 GNSS position data
129283 Cross track error
129284 Navigation data
129285 Navigation route and waypoint info
129539 GNSS dilution of precision (DOP)
130306 Wind data
130310 Environmental parameters
130311 Environmental parameters
130312 Temperature
130313 Humidity
130314 Actual pressure
NMEA 0183 Information
When connected to an optional NMEA 0183 compatible device,
the instrument can receive these NMEA 0183 sentences.
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Sentence Description
BOD Bearing (origin to destination)
DBT Depth below transducer
DTM Datum being used
DPT Depth
GGA Global positioning system fix data
GLL Geographic position (latitude and longitude)
GRMB GPS data
GRME GPS position error data
GSA GNSS DOP and active satellites
GSV GNSS satellites in view
HDG Heading, deviation, and variation
HDM Heading, magnetic
HDT Heading, true
MDA Meteorological composite
MTW Water temperature
MWD Wind direction and speed
MWV Wind speed and angle
RMB Recommended minimum navigation information
RMC Recommended minimum specific GNSS data
THS Heading sensor data
VHW Water speed and heading
WPL Waypoint location
XTE Cross track error
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