Garmin GPS 400W, Installation Manual

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Page 4-6 GNS 400W Series Installation Manual
Rev. G 190-00356-08
4.3 Altitude Gray Code
Altitude input is useful for advisory vertical navigation (VNAV) calculations.
Pin Name Connector Pin I/O
ALTITUDE D4 P4001 70 In
ALTITUDE A1 P4001 69 In
ALTITUDE A2 P4001 68 In
ALTITUDE A4 P4001 67 In
ALTITUDE B1 P4001 66 In
ALTITUDE B2 P4001 65 In
ALTITUDE B4 P4001 64 In
ALTITUDE C1 P4001 63 In
ALTITUDE C2 P4001 62 In
ALTITUDE C4 P4001 61 In
ALTITUDE COMMON P4001 60 In
NOTE
The altitude gray code input is not available when the airframe is configured for
helicopter.
These inputs are considered active if either the voltage to ground is <1.9 V or the resistance to ground
is <375 . These inputs are considered inactive if the voltage to ground is 11-33 VDC.
NOTE
Some transponders and other altitude encoder receivers do not have internal isolation
diodes to prevent the unit from pulling the encoder lines to ground when the unit is off.
These units require a diode added to the installation harness for each encoder line. The
anode should be connected on the receiving unit‘s side and the cathode should be
connected on the encoder side. A set of diodes is required for each unit without internal
diodes. The 400W Series unit includes internal diodes for isolation of the encoder lines.
Refer to Section 5.3.9 for the altitude gray code checkout.
Refer to Figure H-6 for the altitude gray code interconnect.