190-00906-00
GTX 33 Installation Manual
Rev. F
Page 4-7
It is the installing agency’s responsibility to determine that the installed encoder is compatible with the
selected altitude reporting criteria, either 100’ or 25’. Refer to the GNS 480 (CNX80) Installation Manual
or the appropriate GTN 6XX/7XX Installation Manual for the altitude data reporting configuration.
4.5 Discrete Functions
Discrete functions with pin assignments are shown for reference since the functions are available in the
GTX 33. External suppression should be connected if another transponder or DME is installed in the
aircraft avionics system. Depending on system configuration, the Garmin Integrated Flight Deck may not
use these inputs, as many functions are received from the GIA 63 in RS-232 format.
4.5.1 Discrete Outputs
External suppression should be connected if a DME is installed in the aircraft avionics system. The
GTX 33 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 33 mutual suppression output. In this case, leave the suppression pin
open.
*
INACTIVE: 10
≤
Vin
≤
33VDC or Rin
≥
100k
Ω
ACTIVE: Vin
≤
1.9VDC with
≥
75 uA sink current, or Rin
≤
375
Ω
Sink current is internally limited to 200 uA max for a grounded input
4.5.2 DISCRETE INPUTS
*
INACTIVE: 10
≤
Vin
≤
33VDC or Rin
≥
100k
Ω
ACTIVE: Vin
≤
1.9VDC with
≥
75 uA sink current, or Rin
≤
375
Ω
Sink current is internally limited to 200 uA max for a grounded input
Table 4-5. Discrete Outputs
Pin Name
Connector
Pin
I/O
ALTITUDE ALERT ANNUNCIATE*
P3301
19
Out
EXTERNAL SUPPRESSION I/O (TXP/DME)
P3301
31
I/O
SIGNAL GROUND
P3301
51
--
SIGNAL GROUND
P3301
58
--
Table 4-6. Discrete Inputs
Pin Name
Connector
Pin
I/O
EXTERNAL IDENT SELECT*
P3301
12
In
EXTERNAL STANDBY SELECT*
P3301
13
In
SQUAT SWITCH IN
P3301
17
In
TIS CONNECT SELECT*
P3301
46
In
AUDIO MUTE SELECT*
P3301
47
In
Summary of Contents for GTX 33
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