Sandel ST3400H HeliTAWS, Installation Manual

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4.
Discrete inputs actively pulled to 27.5v through 30k ohms when selected ‘active low’ or actively pulled to
0v through 30k ohms when selected ‘active high’ in the maintenance pages. This ensures the input is in the
‘inactive’ state if an external connection fails. If interfacing to discrete signals which do not supply a
“hard” 0Vdc/27.5Vdc transition, any input network may be used that ensures that the discrete input pin is
not within 1.0v from its nominal threshold shown in the table either in the active or inactive state.
5. All discrete outputs sink 50ua current when off.
82046-IM-K ST3400H INSTALLATION MANUAL Page 4-14