Garmin GTX 3x5 Series Installation Manual

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Garmin GTX 3x5 Series Installation Manual Manual pdf 44 page image

190-01499-02 GTX 3x5 TSO Installation ManualRev. 1 Page 5-65.6.2 Altitude Gray Code InputThe parallel Gray code input can be used as a pressure altitude input.The Gray code inputs are pulled down for active, or open for inactive.The GTX 3x5 includes internal isolation diodes on the gray code inputs to prevent the unit from pulling theencoder lines to ground when the transponder is turned off.5.6.3 Altitude Input Selection PriorityCare must be taken to understand the priority for selecting the pressure altitude inputs. The GTX 3x5searches the altitude inputs in a defined sequence and stops when it finds a valid pressure altitude input.5.7 Discrete IOThe discrete inputs and outputs are active low.The discrete inputs are considered active if either the voltage to ground is ≤ 3.5 Vdc or the resistance toground is ≤ 375Ω. The inputs are considered inactive if the voltage to ground is > 6.5 Vdc or the resistanceto ground is > 100kΩ. If the input functions are not needed or not used, they should be left open.Pin Name Connector Pin I/OALT A1 P3251 10 IALT A2 P3251 32 IALT A4 P3251 53 IALT B1 P3251 11 IALT B2 P3251 33 IALT B4 P3251 54 IALT C1 P3251 12 IALT C2 P3251 34 IALT C4 P3251 55 IALT D4 P3251 13 IGROUND (altitude Gray code ground) P3251 56 OPin Name Connector Pin I/OEXT STANDY P3251 14 IALTITUDE ALERT OUT P3251 17 OTEST MODE P3251 35 IEXT IDENT (momentary input) P3251 36 IAUDIO MUTE P3251 37 IAIR/GROUND P3251 57 ITIS-A SELECT P3251 58 IDISC IO1 P3251 15 I/ODISC IO2 P3251 16 I/ODISC IO P3252 13 I/ODISC IO P3252 14 I/O