User's Manual

12
Wiegand Signal Levels
Voh = Output Voltage idle high
Vol = Output Voltage active low
Reader output interface and pull-up resistors
The SmartID
TM
readers provided true open collector outputs for
Wiegand/Clock&Data ABA track 2 emulation. This means the data output is
not voltage driven.
External pull-up resistors are required when the controller does not provide
internal pull-up resistors. The typical value for the pull-up resistors is 1 kOhm.
The recommend position to place the pull-up
resistors is at the controller side.
The pull-up resistor #1 connects form Data/D1 (reader connector pin 3) to a 5
Volt reference.
The pull-up resistor #2 connects form Clock/D0 (reader connector pin 4) to a 5
Volt reference.