GARMIN GTX 345DR G3X Touch Pilot’s User Guide

G3X Touch Pilot’s Guide Addendum for the GTX 345DR

Beginning with G3X Touch software version 8.81, the G3X Touch can be configured to provide display and control for the GTX 345DR transponder with Extended Modes (IFF Modes 1 and 2) enabled. IFF (Identification Friend or Foe) is the military designation used by Air Traffic Control (ATC) to identify and track military aircraft. The GTX 345DR transponder does not support IFF Modes 4 or 5. In addition, support for Mode A/C Lock remote control was also added to provide a means to inhibit all transmissions that include aircraft identification (ICAO address, tail number, flight ID, etc.) and position data.
Only the GTX 345DR transponder is compatible with the G3X Touch for this purpose. These features must be enabled on the transponder using the GTX PC tool (all other configuration items are handled by the GDU). Once a transponder with these features enabled is connected to the G3X Touch, the Transponder Configuration Page displays new configuration items, and new user interface controls.

Contents hide

7 Documents / Resources

7.1 References

8 Related Posts

CONFIGURATION

EXTENDED MODES
When a transponder with extended modes enabled (using the GTX PC tool) is connected to the G3X Touch, the following new configuration items are displayed on the Transponder Configuration Page:

Mode 1 Code Length – Selects the number of digits to be used for Mode 1 IFF codes. The default is two, which allows for up to 32 IFF codes. You can select four, allowing up to 4096 codes.
Emergency Mode Discrete – When enabled, a discrete input on the GTX will be configured as an additional way to trigger the IFF emergency mode (pin 10 on GTX J3251, active low). Due to the way the GTX works, IFF emergency can always be enabled via our user interface, but the discrete input takes precedence when active.

MODE A/C LOCK
When a transponder with Mode A/C Lock enabled (using the GTX PC tool) is connected to the G3X Touch, the following new configuration item is displayed on the Transponder Configuration Page.

Mode A/C Lock Discrete – If enabled, Mode A/C Lock is only controllable via discrete input to the transponder (GTX J3251, pin 11, active low), and is not controllable through the G3X Touch user interface.

PILOT INTERFACE

EXTENDED MODES

Each IFF mode has its own code and can be enabled or disabled individually.

The Mode 3/A code in the data bar is displayed in green when airborne, Mode 3/A is enabled, and the transponder is not in Standby mode. The 1, 2, and 3 characters are displayed in either white or gray, which indicates their enabled/disabled state. The mode is highlighted green when the transponder is replying.

IFF EMERGENCY MODE

When Emergency Mode is enabled, the GTX 345DR includes emergency data replies to Mode 1, 2, and 3/A interrogations. Also, the Mode 3/A code is held at 7700 while Emergency Mode is active. Once Emergency Mode is disabled, Mode 3/A reverts to the code previously entered by the pilot prior to enabling Emergency Mode. Emergency Mode can be enabled or disabled by either a button on the GDU or by an optional discrete input and toggle switch.
Both controls are available if the toggle switch is used. If a toggle switch is used, it is wired as a discrete input to the GTX 345DR unit and it will override the GDU button when switched on. The toggle switch should be guarded to prevent accidentally enabling Emergency Mode.
The GDU button can control emergency mode while the toggle switch is switched ‘OFF’. The GTX 345DR automatically exits ‘Standby’ when the emergency mode is activated. A command to put the GTX into ‘Standby’ will be ignored while Emergency Mode is active.
ALTITUDE REPORTING
The Altitude Reporting button toggles Altitude Reporting On/Off. When Altitude Reporting is ‘On’, altitude data is included in replies to Mode C and S interrogations (when enabled) and ADS-B out squitters (when enabled). When Altitude Reporting is ‘Off’, altitude data is not included in these replies/squitters.
NOTE: For the GTX 345DR to transmit altitude in Mode C replies, Mode 3 must be set to ‘Normal’ (not ‘Standby’). The same is true for Mode S and ADS-B transmissions; in addition, ADS-B Mode S Inhibit (Mode A/C Lock) must be disabled and ADS-B Transmit (when control is present) must be enabled.

FUNCTION

Touching the Normal button allows for the normal operation of all enabled modes. Touching the Standby button places the transponder in ‘Standby’ which disables all transponder RF transmit capability. The option to place the transponder in ‘Standby’ is not available while in emergency mode.
MODE A/C LOCK
Touch the ADS-B/Mode S Inhibit button to inhibit all ADS-B out transmissions, all replies to Mode S interrogations, and acquisition squitter transmissions. The GTX 345DR reverts to ATCRBS (Air Traffic Control Radar Beacon System) the only operation, therefore, it will continue to reply to Mode 1/2 (if the extended modes feature is enabled), and Mode 3/A/C interrogations regardless of aircraft air state.
The intent of this feature is to provide a means to inhibit all transmissions that include aircraft identification (ICAO address, tail number, flight ID, etc.) and position data. This feature does not prevent the aircraft from being tracked as it will still reply to Mode 3/A/C
interrogations if Mode 3 is enabled.
ADS-B/Mode S Inhibit mode can be enabled by either control on the GDU or by a separate toggle switch. Only one of these can be used in the installation. If a toggle switch is used, it is wired as a discrete input to the GTX 345DR unit and the GDU control does not appear. When the toggle switch is not used, control and status are provided on the GDU. Also, when the toggle switch is not used, the ADS-B TX button may be configured to appear on the Transponder page for another level of control over 1090 ES transmissions, while not inhibiting Model S.
The ‘NO MODE S TX’ and ‘NO ADS-B TX’ CAS messages are displayed when ADS-B / Mode
S Inhibit is active. The ‘NO ADS-B TX’ CAS message is displayed when ADS-B TX is disabled.

ADS-B TRANSMIT

The ADS-B Transmit button toggles ADS-B out On/Off. When disabled, 1090 ES transmissions do not occur. When enabled, 1090 ES transmissions occur when the unit is not in Standby, Mode 3 is enabled, and the Mode A/C Lock toggle switch is set to ‘Disable’.
The ADS-B Transmit button is only available in installations that use an external toggle switch to control Mode A/C Lock, or if the Mode A/C Lock feature is not enabled. Otherwise, the ADS-B/Mode S Inhibit button is displayed. In addition, the ADS-B Transmit button is only displayed if the GTX is configured to allow pilot control of ADS-B out.

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