Access control devices and their applications
Installing and wiring access control systems
Burglars and other intruders gain access to a home in a variety of ways. However, according to published statistics, 65 percent of them gain access to a home through one of a home’s doors. Only 6 percent of these uninvited
Access control systems include several features that are typically included in many residential security systems. However, home access security can be installed without the need for a whole-house security system. This chapter covers those devices and systems that can be installed solely to provide access control security to a home.
See Chapter 31 for more information about residential security system basics.
A home access control system can be very simple and involve only such things as standard door locks. It can also be very complex and include the latest biometric devices straight out of the James Bond world. The level of complexity required for any home depends on two issues: the level of security required by the homeowners and their budget.
An access control system is any combination of devices that secure a home and prevent or detect an unauthorized entry through a door, window, or other exterior feature that can be used to gain access to a home. For the majority of homeowners, the access control system in use is limited only to a key-locking door handle and perhaps a deadbolt lock on the front and maybe the rear doors of the home. Often, sliding glass doors and the like are secured only with a toggle lock that is really not all that burglarproof. Adding additional access control security to any home can only make it safer.
Residential access control systems consist of a variety of devices that can be used to gain access to a secured home. The devices that are most commonly
Card reader systems scan coding on a credit card- or smaller-
Most basic card readers only read a number from each card and transfer it to the card reader’s control unit or to the security system controller for processing by either the standard software or custom programming, respectively. More sophisticated systems offer the capability to create customized software, using C-language programming or a Windows- based interface on the card reader controller.
Depending on the type of card system in use, the need and the complexity of the actions that can be programmed into the system vary from very simple read-only features to Smart Card systems that can be used to activate a wide range of home security and automation actions. As the capabilities of the system increase, the level of programming required to customize the system also
The most common card reader systems used in residential applications are
Magnetic stripe readers
Proximity card readers
Wiegand proximity card readers
Depending on the type of card the card reader is designed to scan, the wiring or connectors will vary. Card readers that are designed to interface with computer equipment directly will have either a 9-pin DB connector (DB-9) or an RF-45 plug. Some include a six or more position screw terminal strip to which the ground, power, and relay wires are connected. Powerline communications (PLC)-compatible card readers must be wired to a transformer that provides both the electrical power and the connection to the alternating current (AC) powerlines. Figure 36-1 illustrates the wiring required for a PLC card reader.
Figure 36-1: The wiring configuration of a PLC card reader connected to an electric door strike
The technology of a barcode reader is quite similar to the readers used in the checkout stands at most supermarkets and chain stores. The primary difference between the home security barcode reader and the ones at the store is that in home systems, the barcode is swiped through a reader and not scanned.
The barcode encoded information, which is typically either a card number or a personal identification number (PIN), is printed on a plastic credit card sized card or on a paper card that has been laminated to prevent wear.
Actually, the reader reads the white (or dark gray) spaces of the barcode and not the black
Figure 36-2: An example of barcode, similar to what is found on barcode reader access control system cards
On the back of virtually all credit and automatic teller machine (ATM) cards is a black or reddish-brown stripe that is permanently magnetized with information, and in the case of home access security cards, it is a card number or PIN. When the card is passed through a magnetic stripe card reader, the reader picks up the electromagnetic fields of the stored information and
There are two types of magnetic stripe cards: low coercivity and high coercivity. Low coercivity cards are easily damaged by a wide variety of magnetic sources, including other types of magnetic stripe cards that they may come into contact with in a wallet or purse. High coercivity cards are less easily damaged and are able to hold their information even when in contact with low-grade magnetic sources.
Coercivity is the strength of a magnetic field required to reverse the polarity on a magnetic medium.
High coercivity cards are more reliable because they are more resistant to common magnetic forces. However, the reliability of any magnetic stripe card depends on the magnetic film tape used on the card. The magnetic force that can erase a magnetic stripe card is coercive force, which is measured in Oersteds. A standard
Figure 36-3: A magnetic stripe reader can be a stand-alone device like this one or built into another device.
Photo courtesy of Scan Technology, Inc.
Magnetic stripe readers are not a good option in areas where dust, dirt, heavy rains, or fog are a problem. Dust and moisture can cause the stripe reader to misread or fail altogether.
Unlike magnetic stripe card readers or barcode card readers, a proximity card reader doesn’t require a card to be inserted into the reader. When a proximity card is held near (in the proximity) the card reader, from two inches to six feet from the reader, the reader is able to detect the information on the card and capture it for processing.
Proximity cards and readers use
Many proximity card reader models also include a keypad like the one shown in Figure 36-4. On systems that require two levels of security, the keypad is used to enter a PIN after the card is scanned. On other systems, the keypad can be used in lieu of the card reader.
Figure 36-4: A proximity card reader with a keypad
Photo courtesy of HID Corp.
The primary benefit of a proximity card reader is convenience to the
Wiegand cards have special electromagnetic wires embedded in them in a specific pattern that is unique to each card. Like a standard proximity card reader, the cards and readers communicate using low-frequency radio waves. Because of this, they are virtually
The Wiegand technology
Figure 36-5: A Wiegand keychain sized “pocket tag” proximity card
Photo courtesy of HID Corp.
One more bit about access cards: every card, regardless of the type, is manufactured with a unique facility or site code. This code differentiates one user’s cards from another and
Keypad access control systems require a user to enter a multiple-digit code to gain access. Keypad units (see Figure 36-6) typically have a 10-digit number pad where the user can punch in her pass code.
Figure 36-6: A keypad access control unit
Photo courtesy of Kenny International.
Keypad systems are a good low-cost option in low-risk situations. This system is safe as long as the code stays secret. However, resetting the numerical code is simple using access directly on the keypad through an administrative number code.
The wiring requirements for a keypad access control device depend on the devices the keypad will control, such as an electric door strike, or the other systems the keypad is to be connected to. If the keypad and a door strike are from the same manufacturer, it is likely that documentation details the wiring requirements of the two devices. However, if the keypad is to be used as a stand-alone key entry device that
In every case, study the manufacturer’s documentation before beginning the installation of the keypad, which should normally happen during the trim-out phase. Some keypad devices may include a user interface connection on the internal circuit board that accepts a strip connector with up to 12 wire
On basic keypad devices, electrical wiring no larger than 16 AWG should be used to connect the keypad to its power source and a door strike, if used. Either
Keypad systems can be programmed for several features, including settings that allow entry only during certain hours of the day, eliminating unauthorized access during set periods of the day or night. Programming a keypad system can be done a number of ways. The most common method to program the functions of a keypad system is to press the keys in certain sequences, according to the manufacturer’s documentation. Uploading a keypad’s program from the system controller or downloading the program from the system controller is another common way to program some keypads. In many cases, a computer-based programming interface is used to create keypad programming on the system control unit and then uploaded to each keypad.
An electronic key system (see Figure 36-7) works
Figure 36-7: An IR-remote control deadbolt
The advantage of an electronic key system is that a home’s locks don’t have to be rekeyed should a key be lost or stolen. Instead, the system can be easily reprogrammed to make the lost key inoperable.
Spare or new keys are typically assigned a pass-code number using a separate device called a key programming unit and the electronic cylinder or door lock unit can be programmed for additional key
Electric door lock systems are typically used in conjunction with an authorization device, such as a card reader, electronic key, or keypad. This type of access control device can be used to limit both entry and exit through a door. A card reader and other authorization systems send signals to an access control panel or directly to a connected device, such as an electric door lock. These signals, if received on the appropriate relay, instruct the lock to release the door.
Electric door locks consist of a number of components, including electric strike plates, magnetic locks, drop bolts, and electric locksets. However, not every door will work with an electric door lock and the door lock system needs to be fitted to the door, doorknob, and latch in each case.
A wide variety of products fall within the general category of electric locks, including remote control deadbolts, push-button and keypad door locks, and electric door strikes that can be used to upgrade an existing mechanical door lock.
A remote control deadbolt, see Figure 36-8, works essentially the same way a manually operated deadbolt does. The difference is that remote control deadbolts can be locked or unlocked using a multiple-function infrared (IR) remote control in addition to allow for manual operations.
Figure 36-8: An electronic key that is used with an electronic door lock system
Photo courtesy of Intellikey Corp.
Push-button and keypad door lock systems are keyless locks that can be unlocked by entering a code number sequence by pressing
Figure 36-9: A keypad deadbolt or door lock eliminates the need for a mechanical key.
Photo courtesy of Weiser Lock.
There are mechanical and electronic versions of this type of door lock system. A mechanical (nonelectric) push-button lock (see Figure 36-10) requires its buttons be pressed in a certain sequence.
Figure 36-10: A mechanical push-button door lock
One or more AA batteries are typically used to power an electronic keypad door lock. These devices, like the one shown in Figure 36-10, electrically retract the locking mechanism in the door latch when the correct sequence of keys is pressed. Programming, which typically means entering or changing the number set and sequence, is accomplished through the keypad.
Electric door strikes are available in a variety of styles to fit a variety of door materials and should be
Figure 36-11: An electric door strike provides remote door lock control.
Photo courtesy of Rutherford Controls International Corp.
Several door lock system manufacturers also offer electric door strikes that are compatible with their standard door locks. Electric strikes operate on either 12- or 24-volt direct current (DC) or on AC power. Most electric strikes include a fail secure feature that keeps the door locked should the power source fail.
The installation of an electric door strike is performed much like the installation of a standard nonelectrical door strike in that the strike is installed into the door frame or on a wall in line with the door’s latching mechanism. The primary difference between an electrical strike and a nonelectrical strike is cabling.
The wire size installed to carry electrical signals to the strike varies by manufacturer, but one thing nearly all manufacturers agree upon is that the wiring must be
Figure 36-12: A wire-to-wire connector of the type commonly used with wiring for door strikes and other access control devices
Biometric access control systems use a feature of the users’ bodies to verify their identities, such as fingerprints, facial features, and even retinal patterns. For residential systems, the most commonly used biometric system is one that uses
Figure 36-13: A fingerprint biometric access control system
Photo courtesy of Precise Biometrics.
The advantage of biometric access control systems should be obvious. There are no keys, cards, or codes to lose or forget. The homeowners carry their security devices with them at all times—right on the tips of their fingers, on their faces, or in their eyes.
The wiring required for a biometric access control system depends on the application. Biometric units produce a
Wiring for biometric units can vary, but for the most part, four to six conductors of UTP wiring is required. Many units feature either RJ-45 or RJ-12
Programming a biometric unit, which is typically done through its keypad or interface, involves training the unit to record and recognize the hands, fingers, eyes, or other anatomical features of authorized users. Some additional programming may be required if the unit is to take more than a single output function. As the programming
Some high-end biometric units also record an exportable log file that can be accessed through a network or serial interface. The log file records all successful and, perhaps more importantly,