CV-940 Series
Page 18 of 19
10. WIEGAND Protocol Description
The data is sent over the lines DATA 0 for the logic “0”
and DATA 1 for the logic “1”. Both lines use inverted
logic, meaning that a pulse low on DATA 0 indicates a “0”
and a pulse low on DATA 1 indicates a “1”.When the lines
are high, no data is being sent. Only 1 of the 2 lines
( DATA 0 / DATA 1 ) can pulse at the same time.
Example: data 0010....
Data bit 0 = approximately 100 us (microseconds)
Data bit 1 = approximately 100 us (microseconds)
Time between two data bits: approximately 1 ms
(millisecond). Both data lines (D0 and D1) are high.
5V
0V
5V
1 ms
100 us
0V
D0
D1
1
0
0
0
Description for the 26 bits Wiegand format
Each data block consists of a first parity bit P1, a fixed 8 bits header, 16 bits of user code and a 2nd parity bit P2. Such
a data block is shown bellow:
Parity bit (bit 1) + 8 bits header
+
16 bits user code = 2 bytes
+
Parity bit (bit 26)
P1
XXXXXXXX
XXXX
YYYY YYYYYYYY
P2
Example:
170
31527
1
1 0 1 0 1 0 1 0
0 1 1 1
1 0 1 1 0 0 1 0 0 1 1 1
0
Note:
Parity bits are calculated as follows:
P1 = even parity calculated over the bits 2 to 13 (
X
)
P2 = odd parity calculated over the bits 14 to 25 (
Y
)
E A A A A A A A A B B B B B B B B B B B B B B B B O
11. Safety Precautions
•
Do not install the device in a place subject to direct sun
light without protective cover.
•
Do not install the device and cabling close to a source
of strong electro-magnetic fields like radio-transmitting
antenna.
•
Do not place the device near or above heating
equipments.
•
If cleaning, do not spray or splash water or other
cleaning liquids but wipe it out with smooth cloth
or towel.
•
Do not let children touch the device without supervision
Note:
that if the sensor is cleaned by detergent, benzene
or thinner, the surface will be damaged and the fingerprint
can’t be entered.
