Sandel ST3400H HeliTAWS, Installation Manual

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6.5 Page 5: DISCRETES
The Discretes page shows all the discrete inputs.
A Discrete may be VALID-LOW or VALID-HIGH. In either case a 30K resistor is connected
to pull the signal to the invalid state (ground or aircraft power) as applicable unless the valid
signal is applied.
Back Course (from the HSI) discrete input may be ACTIVE-LOW or ACTIVE-HIGH (Valid
Sense). This is used to inhibit the Glideslope alert GPWS mode 5.
Configuration Field Options Comment
BCKCRS
NONE
ACTIVE L
ACTIVE H
429
Configures the back course input discrete.
GEAR
NONE
DOWN L
DOWN H
429
Configures the gear input discrete.
NVIS
NONE
ACTIVE L
ACTIVE H
429
Configures the NVIS enable discrete.
Only available on units equipped with NVIS
capability.
82046-IM-K ST3400H INSTALLATION MANUAL Page 6-7