Garmin GPS 400W, GNC 420W Installation Manual

Also see for GNC 420AW: Maintenance manual Pilot's guide addendum Quick reference guide Pilot's Guide & Reference Pilot's Guide & Reference

Contents

Garmin GPS 400W, GNC 420W Installation Manual Manual pdf 64 page image

Page 4-6 400W Series Installation ManualRev. E 190-00356-024.3 Altitude Gray CodeAltitude input is useful for advisory vertical navigation (VNAV) calculations.Pin Name Connector Pin I/OALTITUDE D4 P4001 70 InALTITUDE A1 P4001 69 InALTITUDE A2 P4001 68 InALTITUDE A4 P4001 67 InALTITUDE B1 P4001 66 InALTITUDE B2 P4001 65 InALTITUDE B4 P4001 64 InALTITUDE C1 P4001 63 InALTITUDE C2 P4001 62 InALTITUDE C4 P4001 61 InALTITUDE COMMON P4001 60 InThese inputs are considered active if either the voltage to ground is <1.9 V or the resistance to groundis <375 Ω. These inputs are considered inactive if the voltage to ground is 11-33 VDC.NOTESome transponders and other altitude encoder receivers do not have internal isolationdiodes 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. Theanode should be connected on the receiving unit’s side and the cathode should beconnected on the encoder side. A set of diodes is required for each unit without internaldiodes. The 400W Series unit includes internal diodes for isolation of the encoder lines.Refer to Section 5.3.9 for the gray code altitude checkout.Refer to Figure H-6 for the gray code altitude interconnect.