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Reformat proximity card numbers from 16-bit to 24-bit

Reference Number: AA-00253 Views: 22601 Created: 2011-06-01 08:38 Last Updated: 2011-06-01 10:24

First, Some Technical Background:

There are many different proximity card formats, but the proximity cards that we sell are encoded with a "Standard" 26-Bit Wiegand format.  This format actually contains two sets of numbers:

  • A 3-digit "facility code", which can range from 1-255
  • A 5-digit "card number", which can range from 1-65,535.

Most HID proximity cards and key fobs have the 5-digit card number printed on the card.  The 3-digit facility code, however, is printed only on the box in which your cards are shipped.

GateKeeper can be configured to interpret the Wiegand data as either a 16-bit number or a 24-bit number.  The 16-bit number will contain only the 5-digit card number.  The 24-bit number will contain the facility code and card number for a total of 8 digits.  For example, if the facility code for a card is "123" and the card number is "56789" then the 24-bit (8-digit) number read from the card will be "12356789".

A very good white paper "Understanding Card Data Formats " can be found at:

Why would you need to reformat the card numbers?

If you have imported data from another system, then you may have only the 5-digit card number for each member.  This will work fine as long as none of the card numbers overlap with your Gym Assistant Membership Numbers.  If there is overlap then you should start using the full 8 digits for each proximity card, which will ensure that the membership numbers and card numbers are unique.

How to reformat the card numbers:

Reformat card #s
"Reformat Prox Card Numbers"

  • First, Backup your data!  Select Backup Data/To Disk from the File menu.
  • Select Special Features
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