Recently, our CEO, David Carta, called me into his office and asked me, “Mark, what is Wiegand?” He was instructing a new Telaeris employee about XPressFreedom, our Wiegand to Ethernet converter which we use to enable mobile access control with existing system. He thought that I, as our sales lead, should be able to give an appropriate explanation. Like a deer in the headlights I froze, knowing that I did not have a solid, technically sound answer. Feeling the gaze of our newest employee upon me,
I threw a panicked cookie-cutter answer against the wall, hoping that it would be satisfactory. It wasn’t and I knew it. Worse, I knew Dave knew it. Fortunately, he didn’t lambaste me in front of our new co-worker, but as I left the room, my tail was hanging between my legs.
Later that day, Dave called me into his office to address the encounter from earlier in the day. Part of Telaeris’ culture is to deliver the very best support and knowledge to our clients, in our efforts to be the worldwide leader in mobile access control solutions. As our primary salesperson, he wanted to be sure that I could provide top notch technical knowledge, in order for me to provide the very best service possible to our customers. Dave’s instruction to me came in the form of a challenge, “Mark, I want you to write our next blog article about Wiegand.”
Bastante simple, ¿verdad? Con Google y la totalidad de la World Wide Web al alcance de mi mano, hice una investigación ligera y rápidamente preparé un borrador y se lo presenté a Dave. "Mark, esto no es técnicamente exacto. Regresa y profundiza ”. Me abroché el cinturón y continué investigando la historia de Wiegand y cómo funciona. Descubrí que si bien la tecnología comenzó con cables magnetizados, hoy Wiegand se refiere a una interfaz completa en la que se basa la industria del control de acceso. Aún más, aprendí que no estaba solo en mi confusión. Muchos otros compartieron mi pregunta, "¿Qué es Wiegand?"
John R. Wiegand moved from Germany to the United States in the 1930’s, in order to study piano and choral conducting at New York’s world famous Julliard School of Music. He later became an engineer, but it was his perfect pitch that allowed him to hear changes that occurred as his wires were magnetized that led to his discovery of the Efecto Wiegand en los primeros 1970.
Alambre wiegand, patented by Wiegand in 1974, is composed of a magnetic iron-alloy that is designed to form a hard outer casing around a softer inner core. When passed through a magnetized field, the outer shell magnetizes quickly until it reaches full capacity. Once this occurs, the inner core begins to magnetize, and then surprisingly, the core and shell switch polarity. This creates a significant voltage pulse until the wire reaches full magnetization, then it reverts back to its original polarity. These voltage changes are easily detectable.
A finales de los 1970, Wiegand y su socio de negocios, Milton Velinsky, desarrollaron una tarjeta utilizando cables Wiegand para fines de control de acceso. Colocaron dos filas separadas de cables en la tarjeta, que cuando pasaron sobre un campo magnético, crearon salidas de voltaje variables que se tratan como una señal. los Interfaz wiegand is for readers that could detect these cards output data over two signal lines called D0 (Data Zero) and D1 (Data One). This sequence of 1XCHARXs and 0XCHARXs mapped to a binary number. WiegandXCHARXs card was seen as an improvement over existing mag-stripe cards which could be re-written easily. Not only could Wiegand cards not be re-written, they were difficult to manufacture, which meant they were difficult to counterfeit.
Esta interfaz D1 / DO junto con Clock / Data (utilizada para mag-stripe) ha persistido desde los 1970 como las interfaces de facto para el control de acceso
lectores de tarjetas. Cuando la mayoría de la gente hoy habla de un Tarjeta wiegand, they are not thinking about a card with wires. Most often they are talking about an RFID enabled card (i.e. Prox, Mifare, iClass, etc.) that outputs card data using WiegandXCHARXs D0/D1 interface.
A Formato wiegand es simplemente una serie definida de datos binarios transmitidos por los dos cables de salida. El estándar de la industria para el
the first decade was a 26-bit format, using 8 bits for the facility code, 16 bits for the user ID. Today, there are many different and custom formats, with the largest being a 200 bit PIV standard used by the US government. The figure below illustrates the use of 26-bit Wiegand.
Mientras que el Tarjeta wiegand todavía está en producción, en la moderna industria de control de acceso, esta tecnología ha sido reemplazada en gran parte por formas más nuevas, más baratas y más seguras de tarjetas de acceso (es decir, Mifare, iClass, Proximity). Sin embargo, la interfaz Wiegand sigue siendo la convención estándar para la transmisión de datos para cualquier dispositivo (tarjeta, biométrico o lector de PIN) a un panel de control de acceso.
In conclusion, what began as a simple challenge to learn more about Wiegand, quickly became a fascinating learning experience about the roots of the access control industry. Utilized across a broad scope of access control manufacturers, the Wiegand interface is still the beast of the industry, and it refuses to die off. The use of the Wiegand interface technology isn’t going anywhere in the near future, as the depth of its use far exceeds any up and coming technologies. Nearly fifty years ago, John R Wiegand discovered a cool way to manipulate the magnetic polarity of his custom wires; little did he realize that it would redefine an entire industry.
A continuación, dos grandes fuentes de información, ambas escritas por Michael Davis en Wiegand: