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4.2 Power Functions
4.2.1
Aircraft Power
The GRA 5500 provides two aircraft power inputs which accept 14/28 VDC. AIRCRAFT POWER 1 and
AIRCRAFT POWER 2 are "diode ORed" to provide redundant aircraft power connections, such as on
aircraft with two electrical busses. For non-redundant operation, only one input need be connected.
AIRCRAFT POWER 1
AIRCRAFT POWER 2
POWER GROUND
POWER GROUND
4.3 Serial Data Connections
4.3.1
HSDB Over RS-422
The GRA 5500 provides two HSDB (High-Speed Data Bus) over RS-422 interfaces/channels. HSDB is
Garmin's proprietary data bus for use in connecting LRUs to the Garmin Integrated Flight Deck (GIFD) in
GIFD installations. Each HSDB over RS-422 interface consists of two input lines and two output lines and
is physically compatible with EIA/TIA standards for RS-422.
In GIFD installations, GRA 5500 altitude information is outputted from this interface, and all unit
configuration (except for dual/triple unit strapping), calibration, diagnostics, and software upgrades of the
GRA 5500 occur over the HSDB over RS-422 interface. Both HSDB over RS-422 channels are identical,
and only one channel need be connected to the GIFD in order to achieve full unit functionality. However,
for redundancy or failure rate analysis reasons, both HSDB over RS-422 channels may be connected to
provide redundant information.
RS-422 IN 1 A
RS-422 IN 1 B
RS-422 OUT 1 A
RS-422 OUT 1 B
RS-422 IN 2 A
RS-422 IN 2 B
RS-422 OUT 2 A
RS-422 OUT 2 B
190-01277-00
Rev. A
Table 4-2 Aircraft Power
Pin Name
Table 4-3 HSDB Over RS-422
Pin Name
Pin
3
1
2
8
Pin
46
In
35
In
24
Out
23
Out
25
In
18
In
38
Out
42
Out
GRA 5500 Installation Manual
Page 4-3
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