190-00692-00 Rev. BGarmin G1000 Pilot’s Guide for Piper PA321-2SYSTEM OVERVIEW1.2 LINE REPLACEABLE UNITS (LRU)• GDU 1040 – The GDU 1040 features a 10.4-inch LCD display with 1024 x 768 resolution. The left displayis configured as a PFD and the right display is configured as an MFD. The GDU 1040 links and displays allfunctions of the G1000 system during flight. The displays communicate with each other through a High-SpeedData Bus (HSDB) Ethernet connection. Each display is also paired via an Ethernet connection with a GIA 63WIntegrated Avionics Unit.• GIA 63W (2) – Functions as the main communication hub, linking all LRUs with the PFD. Each GIA 63W containsa GPS receiver, VHF COM/NAV/GS receivers, a flight director (FD) and system integration microprocessors.The GIA 63W also contains a GPS WAAS receiver. Each GIA is paired with a respective GDU 1040 displaythrough Ethernet. The GIAs are not paired together and do not communicate with each other directly.• GDC 74A (1) – Processes data from the pitot/static system as well as the OAT probe. This unit provides pressurealtitude, airspeed, vertical speed, and OAT information to the G1000 system, and it communicates with theGIA 63W, GDU 1040, and GRS 77 using an ARINC 429 digital interface. The GDC 74A also interfaces directlywith the GTP 59. The GDC 74A is designed to operate in Reduced Vertical Separation Minimum (RVSM)airspace.
