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.”
Abbastanza semplice vero? Con Google e la totalità del World Wide Web a portata di mano, ho fatto delle ricerche leggere e rapidamente ho gettato insieme una bozza di massima e l'ho presentata a Dave. "Mark, questo non è tecnicamente preciso. Torna indietro e scavare più a fondo. "Mi sono arreso e ho continuato a cercare la storia di Wiegand e come funziona. Ho scoperto che mentre la tecnologia iniziava con i fili magnetizzati, oggi Wiegand si riferisce all'intera interfaccia su cui si basa il settore del controllo accessi. Ancora di più, ho imparato che non ero solo nella mia confusione. Molti altri hanno condiviso la mia domanda: "Cos'è 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 Effetto Wiegand nei primi 1970.
Filo 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.
Nel tardo 1970, Wiegand e il suo socio in affari, Milton Velinsky, hanno sviluppato una scheda usando fili Wiegand per il controllo degli accessi. Hanno posizionato due file separate di fili nella scheda, che quando sono passati su un campo magnetico, hanno creato diverse uscite di tensione che sono trattate come un segnale. Il Interfaccia 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.
Questa interfaccia D1 / DO insieme a Clock / Data (utilizzata per mag-stripe) è persistita dagli 1970 come interfacce di fatto per il controllo degli accessi
lettori di carte. Oggi la maggior parte delle persone parla di a Wiegand card, 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 è semplicemente una serie definita di dati binari trasmessi sui due fili di uscita. Lo standard del settore per il
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.
Mentre l' Wiegand card è ancora in produzione, nel moderno settore del controllo degli accessi questa tecnologia è stata in gran parte sostituita da nuove, più economiche e più sicure forme di carte di accesso (es. Mifare, iClass, Proximity). L'interfaccia Wiegand, tuttavia, rimane la convenzione standard per la trasmissione di dati per qualsiasi dispositivo (scheda, lettore biometrico o PIN) a un pannello di controllo di accesso.
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.
Due grandi fonti di informazione, entrambe scritte da Michael Davis su Wiegand sono qui sotto: