Discrete Functions; Discrete Outputs; Discrete Inputs - Garmin GTX 23 ES Installation Manual

4.2 Discrete Functions

4.2.1 Discrete Outputs

External suppression should be connected if a DME or TCAS is installed in the aircraft avionics system.
The GTX 23 suppression I/O pulses may not be compatible with all models of DME or TCAS. Known
incompatible DME 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 23 mutual suppression output. In this case,
do not connect the GTX 23's suppression pin to the incompatible unit's suppression pin; however, do
connect the GTX 23's suppression pin to any other compatible unit's suppression pin.
Pin Name
EXTERNAL SUPPRESSION I/O (TXP/DME)

4.2.2 Discrete Inputs

Pin Name
EXTERNAL IDENT SELECT*
EXTERNAL STANDBY SELECT*
TIS CONNECT SELECT
* INACTIVE: 10 ≤ Vin ≤ 33Vdc or Rin ≥100kΩ
ACTIVE: Vin ≤ 1.9Vdc with ≥ 75 uA sink current, or Rin ≤ 375Ω
Sink current is internally limited to 200 uA max for a grounded input
EXTERNAL IDENT SELECT (remote IDENT) is a momentary input. When grounded, it activates the
IDENT pulse for 18 seconds in Mode A replies.
EXTERNAL STANDBY SELECT (remote STANDBY) is not a momentary input. When EXTERNAL
STANDBY SELECT is grounded, the GTX 23 operates in standby mode. In this mode, the transponder
will not squitter or reply to interrogations.
TIS CONNECT SELECT is a momentary input. When grounded, it toggles whether TIS is in standby or
operating.
GTX 23 Installation Manual
190-00906-01
Connector Pin
P2301 31
Connector Pin
P2301 12
P2301 13
P2301 46
Page 4-3
Revision A
I/O
I/O
I/O
In
In
In