Schlage HK-CR, User Manual

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HandKey II Manual
13
If one of the outputs is shorted to ground, there will be approximately 5 mA of current
flowing through the short, but no damage will occur. Because of the open collector
structure of the outputs, each output is free to float to whatever external voltage is applied
(when inactive). For example, if one side of a relay coil is connected to an ex12
volt power source and the other side of the relay coil is measured with respect to the
ground of the external power source, the measurement will be +12 volts.
All HandReader outputs are rated at +24 volts DC maximum with a maximum current
draw of 100 mA. This means that it is acceptable to use up to a +24 volt DC external
power supply to energize external devices. Whatever external relay is used should be
chosen to match the external power supply voltage. For example, if the external relay coil
is rated at 15 volts, a 15 volt external power supply should be used. In no case should the
external voltage be higher than +24 VDC.
Each HandReader has a protection mechanism built in to protect against voltage
transients (spikes) coming back into the HandReader from an external relay coil.
Transients from an “opening” or de-energizing relay coil can reach several hundred volts.
This protection is on all HandReader outputs and will limit reverse spikes to approximately
28 volts to protect the open collector transistor driver. HandReader outputs are NOT
designed to switch AC voltages. DC voltages MUST be used and the correct polarities
MUST be maintained.
Relays or devices connected to the lock and auxiliary outputs must not exceed 0.1 A
current draw. NOTE