Garmin G1000 Pilot's Manual page 16

SYSTEM OVERVIEW
• GIA 63 – The GIA 63 is the central Integrated
Avionics Unit (IAU) of the G1000 system. The
GIA 63 functions as a main communication hub,
linking all LRUs with the PFD and the MFD
displays. Each GIA 63 contains a GPS receiver, VHF
COM/NAV/GS receivers, and system integration
microprocessors. Each GIA 63 is paired with a
respective GDU 1040 display through Ethernet.
The GIAs are not paired together and do not
communicate with each other directly.
• GRS 77 – The GRS 77 is an Attitude and Heading
Reference System (AHRS) that provides aircraft
attitude and heading information to both the
G1000 displays and the GIA 63s. The unit
contains advanced sensors, accelerometers and rate
sensors. In addition, the GRS 77 interfaces with
both the GDC 74A Air Data Computer and the
GMU 44 Magnetometer. The GRS 77 also utilizes
GPS signals sent from the GIA 63. Attitude and
heading information is sent using an ARINC 429
digital interface to both GDU 1040s and GIA 63s.
AHRS modes of operation are discussed later in this
document.
1-2 Garmin G1000 Pilot's Guide for Cessna Nav III
• GMU 44 – The GMU 44 Magnetometer measures
local magnetic field information. Data is sent to the
GRS 77 AHRS for processing to determine aircraft
magnetic heading. This unit receives power directly
from the GRS 77 and communicates with the
GRS 77 using an RS-485 digital interface.
• GDC 74A – The GDC 74A Air Data Computer
processes information from the pitot/static system
as well as the outside air temperature (OAT) sensor.
The GDC 74A provides pressure altitude, airspeed,
vertical speed and OAT information to the G1000
system, and communicates with the GIA 63s,
GDU 1040s and GRS 77 using an ARINC 429 digital
interface.
• GEA 71 – The GEA 71 receives and processes signals
from the engine and airframe sensors. Sensor types
include engine temperature and pressure sensors as
well as fuel measurement and pressure sensors. The
GEA 71 communicates with both GIA 63s using an
RS-485 digital interface.
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