Card formats
Different format technologies support a variety of bit-sizes for cards and readers. Bit size alone is not an indicator of a particular format type. For example, within the Wiegand family of formats are many possible bit sizes (26, 34, and many others). This system supports up to a 256-bit Wiegand format.
A format may comprise this information:
- Data bits contain such information as Facility Code, Credential Number, Job Number, and other information. The details of the format specification designate how many data bits are available for each element of information.
- Parity bit(s) serve as a simple accuracy check for the transmitted binary data.
- Total bits is the sum of the parity bit(s) and the data bits. This number is associated with the format name. For example: 26–bit Wiegand, 36–bit HID.
Figure 16. Example of a hypothetical 30-bit format
The example above shows how a format might be set up. The data bits include: six bits for Job Number, six bits for Facility Code, 15 bits for Employee Number, and three parity bits, for a total of 30 bits.
Within a given format bit length, the size and location of the data element, such as, Credential Number or Facility Code may vary. For example, a single 34-bit format may have an eight-bit Facility Code starting with bit number two, or it may have a 12-bit Facility Code starting at bit number 21.
You use the Wiegand Format Editor to create and view card formats, which require this information:
- Total bits
- Number and location of (if any) parity bits
- Parity bit format: odd or even
- Bit total and beginning bit number for Facility Number bits
- Bit total and beginning bit number for Credential bits
- Layout (format) for each parity bit