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What does Wiegand mean?

Wiegand is a wiring standard that is commonly used in access control systems. Since its inception in the 1970s, the Wiegand protocol (sometimes called the Wiegand interface) has become the most popular wiring communication method in the security industry.

In a basic access control system, a Wiegand connection is used to facilitate communication between the reader and the controller. When a user approaches the reader and presents their credential, it is this connection that transfers data from the scanned credential to the controller. The controller can then determine whether or not to allow access. Wiegand readers can be either traditional card readers, or biometric readers such as fingerprint scanners or facial recognition cameras.

A set of icons representing electrical wiring, sending a signal, and a padlock for security

A black plastic keypad is mounted on a white wall with blue illuminated keys. A person's hand holding a white access card is reaching out to present the card to the keypad for access control validation

What does 26-bit mean?

When looking at Wiegand readers and credentials, you may sometimes see the term ’26-bit Wiegand’ or ’26-bit format’. This refers to the most common variant of the Wiegand protocol, which is now very widely used in access control systems. The 26 bits describe the way the binary code that is transferred through the system is organised.

The 26 bits are made up of:

  • 1 parity bit – this is added to a string of binary code as a means of detecting errors.
  • 8 bits of facility code – this defines the company or site.
  • 16 bits of ID code – this is how individual users are defined.
  • 1 trailing parity bit – another verification bit to ensure the system is working as expected.

A digital graphic with a dark background showing representations of binary code in blue light

The 26-bit format

The limits on the 26-bit Wiegand format are determined by the maximum binary values (0 or 1) that can fit into the bit format. For example, there are 255 possible unique facility codes, because if all 8 of the available facility code bits are set to 1, they equal 255. For ID codes, there are 65,535 possible unique codes, because if all 16 ID code bits are set to 1, they equal 65,535.

26-bit Wiegand is an open format, meaning that the format description and organisation is freely and publicly available for anyone to view and use. As a result, almost all access control systems are compatible with it.

It is important to note that while 26-bit Wiegand is the most common format, there are many others available, with different numbers and formats of bits. The standard 26-bit format is the only one for which the format is dictated by the number of bits (as this format has been standardised). With other bit lengths (34-bit and 37-bit are also used in access control), there may be a wide variety of different formats with the numbers of bits organised in very different ways.

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Why is Wiegand so popular?

Wiegand was invented in the 1970s by a German engineer names John R Wiegand. By the 1980s, it was growing in popularity in the security and access control markets, primarily thanks to its simplicity and robust security.

The 26-bit format was found to be particularly useful throughout the access control industry. Its open format allowed more cross-compatibility between manufacturers than ever before.

At the same time, the open format was vulnerable. As hackers and intruders became more technologically able, the access control industry was forced to respond. The development of secured protocols such as OSDP helped to patch those vulnerabilities. Data security has become one of the top priorities for most businesses today. These protocols use layers of encryption to conceal the data being transmitted, protecting it from interception.

However, the Wiegand protocol remains a popular and commonplace method around the world for passing information from the access control reader to the controller.

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