Discrete Inputs - Garmin GTX327 Installation Manual

4.3

Discrete Inputs

EXTERNAL IDENT SELECT*
XPDR SYSTEM ID PROGRAM*
AIRBORNE SENSE (SQUAT SWITCH)
EXTERNAL SUPPRESSION (TXP/DME)
* These inputs are considered active if either the voltage to ground is < 1.9 V or the resistance to
ground is < 375 Ω. These inputs are considered inactive if the voltage to ground is 11-33 Vdc.
EXTERNAL IDENT SELECT (remote IDENT) is a momentary input. Refer to Figures C-1 and C-2 for
the remote IDENT switch interconnect and to Sections 5.2.6.2 and 5.2.10 for the configuration.
AIRBORNE SENSE (SQUAT SWITCH) IN is an ON or OFF input. The squat switch is one of the
Airborne Determination methods available for sensing airborne status. Input for Airborne Determination
allows automatic start and stop of the flight timer and enables automatic STBY mode selection. Refer to
Figure C-2 for the squat switch interconnect and Sections 5.2.6.2 and 5.2.10 for squat switch
configuration.
EXTERNAL STANDBY SELECT* (remote STBY) is an ON or OFF input used typically for dual
transponder installations. When grounded, the GTX 327 is placed in standby. Refer to the figures in
Appendix C and Section 5.2.10 for the EXTERNAL STANDBY SELECT interconnect.
EXTERNAL SUPPRESSION should be connected if a DME is installed in the aircraft avionics system.
The GTX 327 suppression I/O pulses may not be compatible with all models of DME. Known
incompatible units include the Bendix/King KN 62, KN 64 and KNS 80. These models have an output-
only suppression port and can be damaged by the GTX 327 mutual suppression output. In this case, leave
the suppression pin open. Refer to Figure C-2 for the external suppression interconnect.
GTX 327 Installation Manual
190-00187-02
Table 4-5. Discrete Inputs Pin Assignments
Pin Name Pin Number
8
16
22
17
I/O
In
In
In
In/Out
Page 4-5
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