Where There’s a Wire, There’s a Way
Joe Weber, Sales Director

Access control via card access or telephone entry is becoming a greater demand in our industry. Wiring methods controlling multiple entry points from one central location can be very complicated. As a result, several manufacturers have recently entered the multiple door access control market offering their answer to this growing need. Unfortunately, the various versions being offered today neglect to have a common wiring scheme.

The only consistent wiring scheme I have found is the standard Wiegand wiring scheme, which is used between the card reader and the control panel. However, for more sophisticated systems, this is only the first step in the wiring process. Wiring controllers to computers or adding interface boards can increase access ability and control, but these additions can complicate things as well. The good news is, there are shortcuts to these additional hookups. Wiring that connects the control panel to the computer can easily be accomplished using a phone line and a telephone modem. It is simple, fast, economical, and a reliable way to finish the job.

Additional wiring methods have expanded on the original Wiegand wiring scheme and can be used on more sophisticated applications. For example, RS485 is a wiring scheme that has been around for many years. There are several advantages to using RS485 including its simplistic wiring, which uses a single twisted pair of wires with an overall foil shield. In addition, RS485 can be used up to a distance of 4000’. Finally, all the card readers are independent of each other; therefore, if one card reader fails, the rest of the system keeps operating without a glitch.

There are other notable methods that are just as reliable and in some cases, just as easy to wire as RS485. The 20ma communication loop, RS422, and RS232 are wiring methods that are tried and true. However, it appears that our industry is moving in favor of RS485. The industry philosophy, along with mine, is "Why reinvent the wheel, if you can just improve it?"