Wiegand Byte Order and Code Differences

Wiegand Byte Order and Code Differences

Q1: Why do two readers show different codes for the same MIFARE card?
A: This happens because the two readers interpret the card’s UID in different byte orders. One reader uses big-endian format (normal order, reading bytes left to right), while the other uses little-endian format (reverse order, reading bytes right to left).

Q2: What are big-endian and little-endian byte orders?
A:

  • Big-endian: The reader processes the most significant byte first (left to right).

    • Example result: 1614244782

  • Little-endian: The reader processes the least significant byte first (right to left).

    • Example result: 2926262112

Q3: Why does this issue occur in Wiegand systems?
A: The Wiegand interface is not a strictly standardized protocol. Different manufacturers may implement variations in how bytes are ordered and transmitted. This flexibility can lead to mismatched interpretations between devices such as intercoms and readers.

Q4: How can I fix the code mismatch between readers?
A: Adjust the byte order (endian) setting on one of the devices — either on the reader 1 or on the reader 2 — but only change it on one device, not both. Once both devices interpret the byte order the same way, the output codes will match.


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