71. ACCESS CONTROL WIRING & TYPES OF READERS

There are two options for connecting door hardware to the system"Home run" (typical) configuration: non-intelligent readers that simply read card data are used, all components connect directly to a control panel. Advantages: since the interface between a control panel and a reader is standard, almost any type of reader may be used regardless of the identification technology or manufacturer.


Disadvantagesgenerally there is more cabling to be done and the closet or cabinet containing the control panel may become jammed with cables coming from multiple doors; in case a control panel fails, all doors connected to that panel will be affected. Distributed configuration: intelligent readers are used, all components connect directly to a reader. Advantages: there is less cabling work, maintenance and troubleshooting tasks are usually simpler; in case an intelligent reader fails, the problem is limited to just one door controlled by that reader.


Disadvantages: Intelligent readers are usually bigger and more space is required behind the reader for connecting door hardware components; selection of intelligent readers is not as wide as selection of non-intelligent ones...Types of readers.Access control readers may be classified by functions they are able to perform:Basic (non-intelligent) readers: simply read card number or PIN and forward it to a control panel. In case of biometric identification, such readers output ID number of a user.

Typically Wiegand protocol is used for transmitting data to the control panel, but other options such as RS-232, RS-485 and Clock/Data are not uncommon. This is the most popular type of access control readers. Examples of such readers are RF Tiny by RFLOGICS, ProxPoint by HID, and P300 by Farpointe Data. Semi-intelligent readers: have all inputs and outputs necessary to control door hardware (lock, door contact, exit button), but do not make any access decisions. When a user presents a card or enters PIN, the reader sends information to the main controller and waits for its response.