However, many inconsistent implementations and extensions to the basic format exist. The first parity bit is calculated from the first 12 bits of the code and the trailing parity bit from the last 12 bits. The original Wiegand format had one parity bit, 8 bits of facility code, 16 bits of ID code, and a trailing parity bit for a total of 26 bits. The communications protocol used on a Wiegand interface is known as the Wiegand protocol. An advantage of the Wiegand signalling format is that it allows very long cable runs, far longer than other interface standards of its day allowed. Most card reader manufacturers publish a maximum cable run of 500 feet (150 m). ![]() The high signaling level of 5 VDC is used to accommodate long cable runs from card readers to the associated access control panel, typically located in a secure closet. When a 1 is sent the DATA1 wire is pulled to a low voltage while DATA0 stays at a high voltage. When a 0 is sent the DATA0 wire is pulled to a low voltage while the DATA1 wire stays at a high voltage. When no data is being sent, both DATA0 and DATA1 are pulled up to the "high" voltage level - usually +5 VDC. The Wiegand interface uses three wires, one of which is a common ground and two of which are data transmission wires usually called DATA0 and DATA1, alternatively labeled "D0" and "D1" or "Data Low" and "Data High". A Wiegand-compatible reader is normally connected to a Wiegand-compatible security panel. The sensor in such a system is often a "Wiegand wire", based on the Wiegand effect, discovered by John R. It is commonly used to connect a card swipe mechanism to the rest of an access control system. The Wiegand interface is a de facto wiring standard which arose from the popularity of Wiegand effect card readers in the 1980s. ![]() JSTOR ( January 2021) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed.įind sources: "Wiegand interface" – news Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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