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.”
Sudah cukup mudah? Dengan Google dan keseluruhan World Wide Web di hujung jari saya, saya melakukan penyelidikan ringan dan dengan cepat melancarkan draf kasar dan membentangkannya kepada Dave. "Mark, ini tidak tepat secara teknikal. Kembali dan digali dengan lebih mendalam. "Saya berlutut dan terus menyelidik sejarah Wiegand dan bagaimana ia berfungsi. Saya dapati bahawa walaupun teknologi bermula dengan wayar magnetik, hari ini Wiegand merujuk kepada keseluruhan antara muka yang mana industri kawalan akses berasaskan. Lebih-lebih lagi, saya belajar bahawa saya tidak bersendirian dalam kekeliruan saya. Ramai yang lain berkongsi soalan saya, "Apa itu 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 Kesan Wiegand pada awal 1970.
Wayar 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.
Di akhir 1970, Wiegand dan rakan perniagaannya, Milton Velinsky, mengembangkan kad menggunakan wayar Wiegand untuk tujuan kawalan akses. Mereka meletakkan dua barisan wayar yang berasingan di dalam kad, yang apabila dilepaskan di medan magnet, menghasilkan output voltan yang berbeza yang dianggap sebagai isyarat. The Antara muka 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.
Antara muka D1 / DO ini bersama-sama dengan Jam / Data (digunakan untuk jalur-jalur) telah berterusan sejak 1970s sebagai antara muka de-facto untuk kawalan akses
pembaca kad. Apabila kebanyakan orang hari ini bercakap tentang a Kad 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 Format Wiegand hanya satu siri data binari yang ditakrifkan ke atas dua wayar keluaran. Piawaian industri untuk
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.
Sementara Kad Wiegand masih dalam pengeluaran, dalam industri kawalan akses moden teknologi ini telah digantikan oleh kad akses baru yang lebih murah dan lebih selamat (iaitu Mifare, iClass, Proximity). Antaramuka Wiegand, bagaimanapun, tetap menjadi konvensyen standard untuk penghantaran data untuk sebarang peranti (kad, biometrik, atau pembaca PIN) ke panel kawalan akses.
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.
Dua sumber maklumat yang hebat, yang ditulis oleh Michael Davis di Wiegand adalah di bawah: