Garmin G3X Installation Manual page 324

18.3.2.18 Fuel Flow
The following sensors can be configured for the Fuel Flow input on the GEA 24 or GSU 73:
• Electronics International FT-60
• Floscan 201B-6
The fuel flow input requires calibration (see
Rotax 912iS: For the GEA 24, configure the FUEL FLOW input to "Rotax FADEC" to use fuel flow data
from the Rotax 912 FADEC interface.
The GEA 24 and GSU 73 also have provisions for a second fuel flow input (FUEL FLOW 2) to use in
aircraft that require a second fuel flow sensor for differential fuel flow measurement. If both fuel flow
inputs are configured, the displayed fuel flow will be FUEL FLOW 1 (feed) minus FUEL FLOW 2
(return).
18.3.2.19 Discrete Inputs
The GEA 24 and GSU 73 support up to four discrete inputs (DISCRETE 1 through 4) which can be
connected to a variety of external switches or voltage signals and used to generate system alerts or control
other system functions. For instance, a discrete input could be configured to generate an audible alert and
a CAS (Crew Alerting System) message on the PFD display when an external switch is closed.
To configure a discrete input, first select whether the input should be Active Low or Active High. An
Active High input will be considered active when the input voltage is above an upper threshold, and
inactive when the input voltage is below a lower threshold. An Active Low input will be considered active
when the input voltage is below a certain threshold, and inactive when the input voltage is above a certain
threshold, or if the input is floating (not connected). In general, most switch-type inputs that are either
open or connected to ground should be configured as Active Low. See
for the specific voltage levels used for discrete input sensing on the GEA 24 and GSU 73.
G3X Installation Manual - Engine/Airframe Sensor Configuration
Page 18-12
Section 18.3.3).
Section 15.3.8 and Section 15.8.5.1
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