XceedID / Schlage RFID Credential Formatting - 26-bit Explained

Resolution:

*THIS ARTICLE DETAILS BIT FORMATS.  FOR INFORMATION ON HOW TO TELL WHAT BIT FORMAT EXISTS ON AN XCEEDID/SCHLAGE CREDENTIAL, PLEASE SEE 74083*

RFID credentials, both Proximity and Smart, share commonalities in how they are encoded.

                Cards are typically formatted in either 26-bit (26A) or 37-bit (37X), but they can be usually encoded any format the customer wishes.

                Another article will provide explanation on all the formats.  This article will focus on the simplest: the 26-bit format, common amongst XceedID/Schlage, HID, and others.    

Bit Formatting Example:

In simplest terms, the bit format explains how the binary data (0’s and 1’s) on a card are laid out so an access control system can understand them.  The total of binary digits is dependent on the formatting, so 26-bits will get you a 26-binary-digit number.

                The data within a card looks something like this:

                 10000000100000000000000011

                This is the even parity bit. (We do not need to know anything more about parity bits other than they are there and the system calculates based upon the digit present.)

                This is the facility or site code.  This is important to most access control systems who can judge a card depending upon the site code present.  In 26-bit formatting, this number can be anywhere from 0-255.

                This is the Badge ID or Card Number.  This number helps identify the specific user of the card, and this will usually differ on every card present within a system.  In 26-bit formatting, this number can range from 0-65,535.

                This is the odd parity bit. (Again, does not really matter at a tech support level.)

 

                Sometimes the user will need to know how parity is calculated.  And this is when we use the Bit Format Definition grid.

01	02	03	04	05	06	07	08	09	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26
P	S	S	S	S	S	S	S	S	X	X	X	X	X	X	X	X	X	X	X	X	X	X	X	X	P
E	E	E	E	E	E	E	E	E	E	E	E	E
													O	O	O	O	O	O	O	O	O	O	O	O	O
25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

P = Parity Bit

S = Site/Facility Code

X = Badge ID

E = Even Parity Bit computation

O = Odd Parity Bit computation

 

                This grid is what is used in the main XceedID Bit Format Definition guide.  It not only defines the bit formatting for the site code, badge ID, and parity bits, but it also shows where most systems calculate parity throughout the format.