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4.3.5 AHRS ARINC 429 System ID
Pin
2
AHRS SYSTEM ID PROGRAM* 1
3
AHRS SYSTEM ID PROGRAM* 2
4.3.6
System ID Strapping
AHRS
By hard strapping the program pins listed in Table 4-8 to ground, the GRS 77 is assigned a System ID
identified within the transmitted ARINC 429 words. ID's identify a GRS 77 as an All Call, #1, #2, or #3.
For a single system, the pins are left open (All Call).
The GRS 77 has an associated Source/Destination Identifier (SDI or System ID) that is coded into its
ARINC 429 output messages/labels. The System ID may be used to uniquely distinguish the source of
the GDC 74A ARINC 429 labels in a system with more than one GRS 77. The GRS 77 System ID can be
set to All Call, #1, #2, or #3 for such purposes. Table 4-8 identifies which pins on connector P741 are
used to select the desired System ID.
4.3.7 GRS 77 System ID Strapping
By hard strapping the program pins listed in Table 4-8 to ground or open, the GRS 77 is assigned a
System ID. The System ID is included in each transmitted ARINC 429 word. The System ID indicates
that there is only a single AHRS installed (All Call) or, if multiple units are installed, which AHRS the
data originates from (#1, #2 or #3). When a single GRS 77 is installed in the system, then the pins are
left open (All Call). Table 4-9 shows strapping connections to achieve the desired system ID.
Table 4-9. P771 Strapping to Achieve Desired System ID
System ID Number
All Call
#1
#2
#3
Page 4-6
Revision L
Table 4-8. AHRS System ID Program Pins, P771
Pin Name
ARINC System ID 1
Connections
Description
Pin 2
Open
Ground
Open
Ground
GRS 77/GMU 44 Installation Manual
Data In
Data In
ARINC System ID 2
Pin 3
Open
Open
Ground
Ground
190-00303-10
I/O
In
In
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