Annunciator Outputs - Garmin GNS 480 Installation Manual

2.8.6.2 Heading Synchro Reference Voltage
P5-20 Hdg Synchro Ref Hi
P5-39 Hdg Synchro Ref Lo
A reference voltage must be provided if the synchro heading input is used. This input should be 26 VAC
400 Hz (nominal) and provided by the same source that provides the excitation voltage to the synchro
heading source.
2.8.6.3 Heading Synchro Valid Input
P5-57 Heading Valid In
This input is an active high discrete input that provides synchro heading validity information to the GNS
480. If the voltage on this input is > 9 VDC the synchro heading is considered valid, and if the voltage is
< 9 VDC (or the input is open-circuit) the synchro heading is considered invalid.
2.8.7 A
NNUNCIATOR
Installations in conformance with the requirements specified in this installation manual
may not require the use of any external annunciators, since all annunciations are
provided on the GNS 480 front panel. Refer to 2.5.3 to determine whether or not external
annunciators are required.
All of the annunciator outputs duplicate annunciations available on the front of the GNS 480. These can
be used to drive annunciator lamps to make the annunciation available remotely (such as in the pilot's
primary field of view). All of these outputs are active low (i.e. grounded when active, and open
otherwise). Each is an open collector output capable of sinking up to 400 mA. These outputs are
normally open and are only grounded under the conditions described herein.
2.8.7.1 GPS / Nav Annunciations
P7-17 GPS Indicator Out
P7-18 NAV Indicator Out
The GPS Indicator Out (P7-17) will be grounded when GPS is being used as the navigation source to
drive the Main CDI, and open otherwise. The NAV Indicator Out (P7-18) will be grounded when
VOR/ILS is being used as the navigation source to drive the Main CDI, and open otherwise.
If external annunciators are used for the GPS/Nav annunciation, it is recommended that the GPS
annunciator is labeled "GPS" in white text, and the Nav annunciator is labeled "NAV" in green text.
Alternately, the annunciator may be labeled with "GPS" in black text on a white background, and "NAV"
in black text on a green background. Refer to 2.5.3.2 for additional information on source selection
annunciators
2.8.7.2 Back Course Annunciation
P7-15 Back Course Out
The Back Course Out will be grounded when the back course localizer mode is enabled.
GNS 480 (CNX80) Installation Manual560-0982-01 Rev A
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UTPUTS
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Installation Procedures
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