When the reader communicates (talk to) to the Controller; just like a person talk to the other person, they both shall agree to communicate with “certain way”. Within two persons, they can communicate through email, language, body language, writing … etc. In Access Control business, Wiegand is the standard “language” for a reader to communicate with the Controller. It is a way to transfer the Card ID data back to the Controller.
Wiegand protocol is a unified international standard and a communication protocol developed by Motorola. It is suitable for many characteristics of card reader and card involving access control system. It has many formats, the standard 26-b it should be the most commonly used format. In addition, there are 34-bit, 37-bit formats, and the standard is 26-bit.