TT31 Transponder Installation Manual
8 May 2017
00455-00
Issue AQ
______________________
Trig Avionics Limited
Page 9
5.4.1
Primary Interface – Pinout
Pin Signal
Direction
1
Ground
-
2
Lighting 14V
Input
3
Lighting 28V
Input
4
Suppress I/O *
Bi-directional
5
Squat Switch In *
Input
6
RS232 Output 1 *
Output
7
RS232 Input 1 *
Input
8
Altitude D4
Input
9
Suppress In
Input
10
Standby Switch
Input
11
11-33V DC
-
12
11-33V DC
-
A
Ground
-
B
Altitude B4
Input
C
Altitude B2
Input
D
Altitude C1
Input
E
Altitude B1
Input
F
Ident Switch In
Input
H
Altitude C4
Input
J
Altitude A4
Input
K
Altitude A2
Input
L
Altitude C2
Input
M
Altitude A1
Input
N
Do Not Connect *
-
*: These signals are different to the KT76A/KT76C/KT78A pinout; on the KT76A, KT76C and
KT78A these signals are not usually connected in the aircraft.
The following diagram shows the connector orientation as it would be fitted to the mounting tray.
