The card reader interface WG26 can transmit 26 bits of data, including the first and last parity bits, and the remaining 24 bits are data bits. The maximum card number that can be transmitted in 24 digits is: 167772 15. Card numbers smaller than this number can be transmitted normally, and those larger than this number cannot be transmitted.

The card reader interface WG34 can transmit 34 bits of data, including the first and last parity bits, the remaining 32 bits are data bits, and the maximum card number that 32 bits can transmit is 4294967295, so WG34 can transmit a relatively large card number.

However, the card reader with WG26 interface is the most widely used in the access control market. Even a card reader with a card number of more than 24 digits will automatically remove the extra digits.