Velleman HAA2866 - Manual (Page 32)

TIMING & ELECTRICAL MANNER OF THE WIEGAND DATA OUTPUT
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. The Wiegand data output from the keypad unit provides a
level of compatibility for readers and control panels that 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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