1. Whether the wiring is normal？

Suggestion: the card reader should have 4 groups of key wires, such as +12V, GND, D0 (WG0), D1 (WG1).

2. Whether the power supply is normal？

Suggestion: the card reader is usually using DC12V working voltage. The red wire should be connected to 12V and the black wire connect to GND.

3. Whether the Wiegand output format of card reader is correct?

Suggestion: card reader have many types which support ID card, Mifare card, HID card and CPU card. Please confirm it’s same frequency with your card before purchased, otherwise, different frequency cannot read card.

4. Wiegand output format incompatible

Suggestion: the card reader uses Wiegand communication mode. And Wiegand is divided into wiegand26, wiegand34, wiegand66, etc., which are different in the length of output card number bytes. When using, please set the Wiegand format according to one standard to avoid inconsistent Wiegand data byte length between devices.

5.Abnormal data transmission caused by long line

Suggestion: generally, the effective length of Wiegand communication is within 0 - 80m. At the same time, the wire material used in the line should be considered. If the line is too long, it is easy to cause incomplete data transmission (For example, the card number is 12345678 when reading the card once, but it showing another number when reading the card again, which is the loss in the middle of transmission.)