Garmin GTX 33 Installation Manual - Page 45

It is the installing agency's responsibility to determine that the installed encoder is compatible with the selected altitude reporting criteria, either 100' or 25'. Refer to the GNS 480 (CNX80) Installation Manual or the appropriate GTN 6XX/7XX Installation Manual for the altitude data reporting configuration. 4.5 Discrete Functions Discrete functions with pin assignments are shown for reference since the functions are available in the GTX 33. External suppression should be connected if another transponder or DME is installed in the aircraft avionics system. Depending on system configuration, the Garmin Integrated Flight Deck may not use these inputs, as many functions are received from the GIA 63 in RS-232 format. 4.5.1 Discrete Outputs External suppression should be connected if a DME is installed in the aircraft avionics system. The GTX 33 suppression I/O pulses may not be compatible with all models of DME. Known incompatible units include the Bendix/King KN 62, KN 64 and KNS 80. These models have an output-only suppression port and can be damaged by the GTX 33 mutual suppression output. In this case, leave the suppression pin open. Table 4-5. Discrete Outputs Pin Name ALTITUDE ALERT ANNUNCIATE* EXTERNAL SUPPRESSION I/O (TXP/DME) SIGNAL GROUND SIGNAL GROUND Connector P3301 P3301 P3301 P3301 Pin I/O 19 Out 31 I/O 51 -- 58 -- * INACTIVE: 10 ≤ Vin ≤ 33VDC or Rin ≥100kΩ ACTIVE: Vin ≤ 1.9VDC with ≥ 75 uA sink current, or Rin ≤ 375Ω Sink current is internally limited to 200 uA max for a grounded input 4.5.2 DISCRETE INPUTS Table 4-6. Discrete Inputs Pin Name EXTERNAL IDENT SELECT* EXTERNAL STANDBY SELECT* SQUAT SWITCH IN TIS CONNECT SELECT* AUDIO MUTE SELECT* Connector Pin I/O P3301 12 In P3301 13 In P3301 17 In P3301 46 In P3301 47 In * INACTIVE: 10 ≤ Vin ≤ 33VDC or Rin ≥100kΩ ACTIVE: Vin ≤ 1.9VDC with ≥ 75 uA sink current, or Rin ≤ 375Ω Sink current is internally limited to 200 uA max for a grounded input 190-00906-00 Rev. F GTX 33 Installation Manual Page 4-7