FreeFlight 2101 I/O Approach Plus Installation And Checkout Manual page 33

2.3.4.4 J2 Wiring Notes
The external wire supplied by the installing agency should be MIL-W-16878E/4 or equivalent, 22 gauge with
the exception of the digital data connections (pins 9, 15, 16, 23, and 57 - 64). Digital data connections require
22 gauge twisted shielded pairs. Refer to pin-out diagram Figure 2-2. For HSI connections, refer to Figure 2-10.
For an overall typical system interconnection, refer to Figure 2-11.
These considerations should be followed to ensure proper connection:
A. The Approach Mode (APPRMODE, pin 26), Approach Enable (APPREN, pin 27), and Leg Change
(LEG CHNG, pin 28) annunciators are connected to open-collector transistors which will sink up to 200
mA max. If connected to a relay for higher current capability, the relay must have a protection diode placed
across the coil. The pins sink current when the annunciator condition is true.
B. The HSI Synchro Valid Flag (HSI VALID, pin 29) and Steering Valid Flag (STR VALID, pin 48), are
connected to transistor switches to aircraft voltage. They can source current up to 200 mA max.
connected to a relay for higher current capability, the relay must have a protection diode placed across
the coil. The pins will source current when the flag condition is true.
C. When using high speed ARINC 429 communications with connections in excess of 10 feet and with
multiple receivers on a single line, additional attention may be required to maximize signal integrity. The
wires should be connected in a daisy-chain from the transmitter to one receiver, then from that receiver
to the next receiver, etc., not as a branching or star arrangement with parallel legs.
D. Pin 39 should be used as a ground reference for low level, low current signals such as A/PLeft/Right
Deviation, pin 50) and the 6 wire output (pins 32, 47 and 49). Pin 41 should be used as a ground return
for high current signals such as Synchro 1, 2 and 3 line Z and Roll Steering common. Connecting any
Synchro Z lines, Roll Steering common, or any reference common to the same pin as the Left/Right return
will cause erroneous Left/Right data to be displayed.
E. In input synchro configurations, ground input synchro "Z" lines to airframe ground per ARINC 407.
F. "Future Use" wiring options may be pre-wired by the installation agency, but will remain inactive until future
software upgrades are available.
Revision E
May 31, 2006
FreeFlight 2101 I/O Approach Plus GPS Navigation System
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