Lighting Bus; Altitude Inputs; Power Configuration And Power Control Functions; Table 5-6 Lighting Bus Pins - Garmin GTX 3X5 Installation Manual

Table 5-5 Power Configuration and Power Control Functions
POWER POWER
CONFIG CONTROL
Open Open
Open Ground
Ground Open
Ground Ground
5.4

Lighting Bus

The lighting bus input controls the front panel display and keypad brightness of panel mount units using
the aircraft panel lighting bus. The GTX 3X5 can also be configured to adjust the display and keypad
brightness for ambient lighting conditions using an internal photo sensor.
The lighting bus input is configured for 5 VDC, 14 VDC, 28 VDC, or 5 VAC inputs.
Use both the LIGHTING BUS HI and LIGHTING BUS LO inputs to connect the lighting bus input to a 5
VAC bus.
Use the LIGHTING BUS HI input to connect the light bus input to a DC input. The return is the unit
ground connection. LIGHTING BUS LO should be left open.
LIGHTING BUS HI
LIGHTING BUS LO
5.5

Altitude Inputs

The GTX 3X5 uses pressure altitude inputs from several different sources:
• Gray code inputs
• RS-232 serial inputs
• ARINC 429 inputs
• The optional GAE module (Garmin P/N 011-03080-00)
• HSDB
Refer to section 3.10 for altitude source priorities.With the proper encoder, the Mode S transponder
transmits altitude reporting in 25-foot resolution to ground stations and other aircraft. The unit must
receive altitude from an applicable altitude reporting device or from the optional GAE module. A parallel
Gray code encoder provides altitude in 100 foot resolution.
For altitude encoders that supply both a serial interface and the parallel Gray code input, such as the GAE
43 (P/N 013-00066-00), connect one or the other interfaces, but not both. The serial interface is preferred.
5.5.1

Pressure Sensor Module

The optional GAE module (Garmin P/N 011-03080-00) is used for the GTX 3X5 pressure altitude input. It
uses the same interface as the configuration module and also includes the configuration module
functionality.
190-01499-02
Rev. 4
Unit Type
Panel mount
Panel mount
Remote
Remote

Table 5-6 Lighting Bus Pins

Pin Name
Description
Auto on disabled, momentary power switch enabled
Auto on enabled, momentary power switch enabled
Power off
Power on
Connector
P3251
P3251
GTX 3X5 Transponder TSO Installation Manual
Pin I/O
19 I
40 I
Page 5-7