HXr Installation Manual GRT Avionics
1-8
Revision A5
import from a third-party GPS to the EFIS are track and position. Flight plan sequencing from such
a GPS can be imported if the GPS is wired to the EFIS through the ARINC 429 port.
When the Grand Rapids Technologies Engine Information System (EIS) unit is installed in the aircraft,
every engine parameter imaginable is able to be monitored through the EFIS system. The EIS
module senses the desired engine or environmental data, such as exhaust gas temperature, cylinder
head temperature, oil temperature/pressure, and outside air temperature, and displays it on both
the EIS screen and the EFIS screen. While the EIS displays it in numerical data only, the EFIS can
display data in graphical format, which is useful and easy to read during flight. One notable feature
is the EGT line graph, which tracks EGT data for each cylinder over time and allows easy and
instantaneous rough-engine troubleshooting. The ENG page on the EFIS is dedicated to engine
and environmental parameters. Engine data can also be displayed on a portion of the primary
flight display page, fully customizable in-flight according to the pilot’s taste and situation.
GRT strives to maintain open compatibility with third-party equipment vendors. This allows aircraft
builders and pilots the freedom to choose whatever brands fit their mission and budget, as well
as the flexibility for easy upgrades as technology evolves. Radios, transponders, ADS-B modules,
and many other third-party units interface with the GRT HXr through RS-232 serial, ARINC 429,
RS-422, and USB ports. VOR/localizer data, traffic alerts, and in-flight weather are very common
additions that are easily displayed on the EFIS screen. The HXr features the capability to mount
the radio, transponder and engine monitor in a remote location to simplify the design of the
instrument panel. The addition of a second or third display unit doubles or triples the number of
available serial and USB ports available, allowing use of more third-party devices. The Ethernet
inter-display link between EFIS screens allows data from most devices to be shared among screens
for redundancy and convenience.
See Section 5, the Appendix of this manual, and the Support section of grtavionics.com for
information on various GRT system & third party equipment configurations.
1.4 Light Aircraft Avionics Primer
Modern flight instrumentation systems may seem intimidating, but they can be simpler to install
than their analog counterparts. This section provides some basic information for aircraft builders
new to the world of electronic flight display systems.
D-Sub Connectors
A key element to designing a glass-panel installation is the communication between different
components of the system. The internal circuits of each unit are wired to use D-sub connectors for
easy external wiring of required and optional components. The main connectors of the Horizon
system are two 25-pin D-Subs, referred to in this manual as Connectors A and B. Each pin of the
connector is wired to an internal component of the display unit circuitry. Some pins are hard wired
to required elements, such as the AHRS input. Others are designated as serial ports or other
communication ports described below.
Analog Input