Garmin G3X Installation Manual page 187

A.1.3 Mode Selections
Configure the GDU 37X units per the following tables.
A GDU 37X can be manually placed in reversionary mode by wiring Pin 25 to a two pole switch that
toggles between open and ground. When the switch is open, the display will operate normally. When the
switch is grounded, the display changes to reversionary mode, showing the engine bar at the top of the
display and a split screen PFD and MFD below. Other displays in the system will not be affected by
manually placing a display into reversionary mode.
Do not connect a switch to ground for pins 9 or 10, doing so can cause communication errors.
Grounding pin 42 will place the GDU 37X in Demo mode, which is for in-store demonstration use only,
never ground pin 42 in an aircraft installation.
CDU SYSTEM ID PROGRAM* 1,
P3701 Pin 10
Open
Ground
Open
Ground
CDU SYSTEM ID
PROGRAM* 3
P3701 Pin 25
Open Auto Reversionary
Ground Forced Reversionary
A.1.4 Serial Data
A.1.4.1 RS-232
3 Channels of RS-232 I/O data.
Pin Name
RS-232 IN 1
RS-232 OUT 1
RS-232 IN 2
RS-232 OUT 2
RS-232 IN 3
RS-232 OUT 3
A.1.4.2 CAN Bus
This data bus conforms to the BOSCH standard for Controller Area Network 2.0-B. This bus complies
with ISO 11898. CAN BUS TERMINATION should be connected to CAN BUS LO for the GDU that is
located at the end of the bus (farthest from the GSU 73).
Pin Name
CAN BUS HI
CAN BUS LO
CAN BUS TERMINATION
G3X Installation Manual – Pinouts
190-01115-01
CDU SYSTEM ID PROGRAM* 2,
P3701 Pin 9
Open
Open
Ground
Ground
GDU Mode
GDU Mode
MFD
PFD1
PFD2
Do Not Use
CDU SYSTEM ID
PROGRAM* 4
P3701 Pin 42
Normal Operation
Open
Ground Demo Mode
Connector
P3701
P3701
P3701
P3701
P3701
P3701
Connector
P3701
P3701
P3701
GDU Mode
Pin I/O
47 In
48 Out
14 In
30 Out
29 In
13 Out
Pin I/O
46 I/O
45 I/O
28 --
Page A-3
Revision E