Garmin G900X Pilot's Manual page 19

• GEA 71 – The Engine Airframe Unit receives and processes signals from the engine and airframe sensors. This
unit communicates with both IAUs using an RS-485 digital interface.
• GTX 33 (1 or 2) – The solid-state Transponder provides Modes A, C, and S capability and communicates with
both IAUs through an RS-232 digital interface.
• GRS 77 (1 or 2) – The Attitude and Heading Reference System (AHRS) provides aircraft attitude and heading
information via ARINC 429 to both PFDs and the primary IAU. The AHRS contains advanced sensors (including
accelerometers and rate sensors) and interfaces with the Magnetometer to obtain magnetic field information,
with the ADC to obtain air data, and with both IAUs to obtain GPS information. AHRS operation is discussed
in Section 1.4, System Operation.
• GMU 44 (1 or 2) – The Magnetometer measures local magnetic field and sends data to the AHRS for processing
to determine aircraft magnetic heading. This unit receives power directly from the AHRS and communicates
with it via an RS-485 digital interface.
• GCU 476 or GCU 477 – (optional) The GCU 476 provides MFD/PFD and radio tuning control through an
RS-232 digital interface. The GCU 477 provides MFD and radio tuning control through an RS-232 digital
interface
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Garmin G900X Pilot's Guide
SYSTEM OVERVIEW
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