Understanding EM-Marine and MIFARE Card Code Differences
Q1: What is an EM-Marine card?
A: An EM-Marine card follows the EM-Marine standard, which uses a short Card Number (UID). Because the UID easily fits within 26 bits, the card always generates the same output code — no matter whether the reader is set to Wiegand 26, 34, or 42 bits.
A: An EM-Marine card follows the EM-Marine standard, which uses a short Card Number (UID). Because the UID easily fits within 26 bits, the card always generates the same output code — no matter whether the reader is set to Wiegand 26, 34, or 42 bits.
Q2: What is a MIFARE tag?
A: A MIFARE tag is based on the MIFARE standard, which uses a longer UID — typically 4 bytes (32 bits), and sometimes even 7 or 10 bytes. This longer UID behaves differently when converted into Wiegand formats.
A: A MIFARE tag is based on the MIFARE standard, which uses a longer UID — typically 4 bytes (32 bits), and sometimes even 7 or 10 bytes. This longer UID behaves differently when converted into Wiegand formats.
Q3: Why does a MIFARE card show different codes at different Wiegand bit settings?
A: Because the MIFARE UID is longer than 26 or 34 bits, the reader must truncate or rearrange data when converting it into shorter Wiegand formats. This causes the output code to vary between Wiegand-26, Wiegand-34, and Wiegand-37 settings.
A: Because the MIFARE UID is longer than 26 or 34 bits, the reader must truncate or rearrange data when converting it into shorter Wiegand formats. This causes the output code to vary between Wiegand-26, Wiegand-34, and Wiegand-37 settings.
Q4: What happens during the conversion process?
A: When the reader processes a MIFARE UID into Wiegand format, it may:
Cut off part of the UID if the bit length is too short (e.g., 26 bits)
Add parity bits
Reorder bytes depending on the Wiegand format
These steps can alter how the same UID is represented in shorter bit formats.
Q5: Why does the code stop changing at higher bit formats?
A: Once the Wiegand format reaches 37 or 42 bits, the entire MIFARE UID fits within the structure. No data is lost or rearranged — so the output code becomes stable and consistent.
Summary of behavior
- EM-Marine cards: Because their UID is short enough to fit within 26 bits, they always produce the same output code, regardless of whether the reader is configured for Wiegand 26, 34, or 42 bits.
- MIFARE cards: Their UID is longer (usually 32 bits or more). As a result, the output code changes when using shorter Wiegand formats like 26 or 34 bits — since part of the UID must be truncated or rearranged. Once the bit format is increased to 37 or 42 bits, the full UID fits into the Wiegand structure, and the output code becomes stable and consistent.
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