TIMING & ELECTRICAL MANNER OF THE WIEGAND DATA OUTPUT
The Wiegand data output from the keypad unit provides a level of compatibility for readers and control panels that
The Wiegand is a commonly used interface between readers and control panels used in access control security and
other related industries. The majority of cards in access control systems use a Wiegand interface to transmit data
read from a card to a control panel. The control panel will then validate the data received and grant or deny access.
can be used by consultants and end users when setting product design or system installation criteria.
The Wiegand interface uses three wires, one of which is a
Common Ground (Wire 5 – Black)
and two of which are
data transmission wires called
DATA 0 (Wire 2 – Blue)
and
DATA 1 (Wire 1 – Yellow)
. When no data is being sent both
DATA 0 and DATA 1 are at high voltage. When a “0” is sent the DATA 0 is at low voltage while the DATA 1 stays at a
high voltage. When a “1” is sent DATA 1 is at the low voltage while DATA 0 stays at the high voltage.
There are also two indication wires for the visible and audible signals feeding back from the control panel. They are
0V active. The
Buzzer Control Line (Wire 3 – Brown)
is audible signal control wire, and the
Red LED Control Line (Wire
4 – Red)
is the visible indication control wire.
The high voltage level in the keypad unit is +5VDC to accommodate for long cable runs (approximate 500 feet) from it
to the associated access control panel typically located in a secure closet.
Diagram of The Wiegand Protocol Timing and Its Electrical Manner
50 uS pulse
Data 0 Line
2 mS pulse interval
Data 1 Line
0
1
0
1
+5V
0V
+5V
0V
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