Altimeter; Synchro Heading - Garmin GNS 480 Installation Manaul

2.8.5

Altimeter

The GNS 480 accepts altitude data serially, using either RS-232 or ARINC 429 inputs. Refer to section
2.8.10 for additional information on the serial interfaces. In addition, the GNS 480 can accept the baro-
correction using the potentiometer output from a suitable altimeter. If baro-correction and uncorrected
pressure altitude are provided to the GNS 480, baro-corrected altitude will be output by the GNS 480.
P5-13 Baro In (W)
P5-33 Baro Hi
P5-53 Baro Lo
The GNS 480 must not be connected in parallel with other equipment using the baro
pot. Damage to the GNS 480 or other the equipment may occur if this is done.
Refer to Appendix D for altimeter baro potentiometer connections to several altimeters. Refer to section
3.2.1.4 for information on calibrating the baro potentiometer input.
2.8.6

Synchro Heading

The GNS 480 accepts heading information using either a synchro input or serially, using either RS-232 or
ARINC 429 inputs. Refer to section 2.8.10 for additional information on the serial interfaces. If synchro
heading is provided, refer to the paragraphs below. Refer to Appendix D for interconnect information.
2.8.6.1 Heading Synchro
P5-19 Hdg Synchro X
P5-18 Hdg Synchro Y
P5-38 Hdg Synchro Z
Connect these pins to an XYZ type directional gyro.
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.
GNS 480 (CNX80) Installation Manual
CAUTION
560-0982-01 Rev L
Installation Procedures
2-27