Format and Facility (Site) Code explained

Definition of "Format"
A proximity card stores data. 
A "format" is the structure of the binary data stored in the card. The number of ones and zeros, and how they are put together, determines the format and ultimately the credential number.  When a card is waved in front of a reader, those numbers are sent to the access controller. However, the controller needs to know how the received information is organized., i.e. the format.

For example, if we see a string of numbers, 19395981699, it may mean nothing to us.  But, if we know it is a phone number, we immediately understand that 1 is the country code for USA, 939 the area code, and the remaining digits, the phone number. It is evident that knowledge of the format allows to properly decode the data.

The 26 bit Wiegand format is the more widely used. Card manufacturers such as HID, Indala and AWID sell cards with this format to any dealer. This 26 bit format is recognized by all access hardware.

Visit our  125khz Proximity Card Selection Guide

Over the years, formats with a higher number of bits (33, 37, 48, 50)  have been added to increase card security.

However, some of the higher bit formats are  "proprietary", and usually carry a higher price tag. One exception is the HID 37 bit proprietary format, priced similarly to a 26 bit card.

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Definition of Facility code and serial number

Every card is assigned a unique serial number, which is recorded in your access control database and linked to a specific cardholder. For 26-bit cards, the serial number range is from 0 to 65,535. The system reads the card number and checks it against the database to grant or deny access. However, if two companies use overlapping serial number ranges, there is a potential risk that individuals could gain access to both companies' premises using the same card number. To reduce this risk, a second number, know as facility or site code is encoded into each card. This number can go from 0 to 255 on a 26 bit format card.

As an example, if Company A has cards numbered from 1 to 1000, with facility code 230, they would be encoded as follows:

230 - 00001
230 - 00002
230 - 00003 .......up to 230 - 01000

Company B could have the same serial numbers, but with facility code 180, and their cards would be:
180 - 00001
180 - 00002
180 - 00003........up to 180 - 01000

An access control system grants entry by validating both the facility code and the serial number. Even if Company A and Company B use the same serial numbers for their cards, access will be correctly managed because the cards will have different facility codes. Therefore, a card from Company A will be rejected at Company B's premises, and vice versa, due to the mismatch in facility codes.

Recently, some card formats (i.e. H10302 37 bit format) have adopted higher bit counts, eliminating the need for facility codes because each card's serial number is unique and never duplicated during production, similar to serial numbers on currency bills. This innovation not only streamlines the manufacturing process but also allows for quicker delivery of cards, including add-ons for existing sites, directly from stock.

Cards ship with a facility code (if used) and serial number programmed and printed outside, by default. The need for using facility codes becomes important when you have a campus of several buildings and you want to prevent cardholders from accessing whole buildings on the campus. Each building can be assigned its own facility code. This makes it easy to prevent the cardholders from entering each others' buildings.

How can I find the part number, format and facility code?

Look at the information printed on the label of one of the boxes where you received your last batch of cards (see example at right)





My card has 0009P printed - is this the format ? 

No - that is the factory number where the card was manufactured.  The format will be found only as described above.

If your installation is new, we can help you to select the format and facility code for you.