Garmin G3X Installation Manual page 246

15.7.2 Aircraft Power
The GSU 25 can operate using power from one or both inputs (AIRCRAFT POWER 1 AND AIRCRAFT
POWER 2). The pins are internally connected using diodes to prevent current from flowing between the
two power inputs. AIRCRAFT POWER 2 is for connecting to an alternate power source, such as on
aircraft with two electrical buses.
AIRCRAFT POWER 1
AIRCRAFT POWER 2
POWER GROUND
POWER GROUND
The GSU 25 outputs supply voltage to the GMU 22 via pins 6 & 7.
+12V MAGNETOMETER POWER
MAGNETOMETER GROUND
15.7.3 Serial Data
15.7.3.1 RS-232
2 Channels of RS-232 RX, and 3 Channels of RS-232 TX data.
RS-232 1: Can optionally be connected to a GDU 37X display to provide a redundant path for attitude
data. Also used to configure a GSU 25 as ADAHRS #3.
RS-232 2: Transmits data to the GMU 22.
RS-232 3: Connects to a GTX transponder to provide pressure altitude data and remote transponder
control. Transponder should only be connected to ADAHRS 1 (not 2 or 3).
RS-232 RX 1
RS-232 TX 1
RS-232 TX 2
RS-232 RX 3
RS-232 TX 3
G3X Installation Manual - LRU Pinouts
Page 15-32
Pin Name
Pin Name
Pin Name
Connector Pin
J251 7
J251 8
J251 6
J251 9
Connector Pin
J252 6
J252 7
Connector Pin
J251 4
J251 5
J252 15
J252 10
J252 9
190-01115-01
I/O
In
In
--
--
I/O
Out
--
I/O
In
Out
Out
In
Out
Rev. L