Electronic keypads have been used to control access since the late 1950s, when the Cypher Lock was developed for United States government installations. This prototype electronic pushbutton lock with separate logic controller eliminated the “key.” To gain access, the access code was entered into the five rocker switches. The correct code had to be entered in proper sequence. Each rocker switch was connected to a relay that had to be tripped in the correct order. Only if all of the relays trip in their correct order would the Cypher Lock will permit access.
Around the mid 1980s, after the computer revolution, keypads started becoming commercially available at reasonable prices. Keypads became incorporated into access control systems and standalone electromechanical locks.
It was during this time, that cylindrical and mortise locks were commercially available with electric locking or unlocking. Previously, for their own applications, locksmiths made the electrically converted locks. For more than 30 years, Architectural Control Systems, Inc. (ACSI) has been modifying and producing electrified locking hardware.
Over the following years, keypads became available in a variety of configurations and functionalities for controlling access. Early keypads were equipped with the software and hardware necessary to operate the lock mechanism in order to control access. This type of standalone keypad was and is still used for a single door access controls system.
Keypads can also be equipped with minimal circuitry to be just a keypad that a user code is entered in order to gain access. They are commonly known as keypad readers. They can be for a single door or as part of a larger system or a system that has a separate database. These single entry point keypads do not contain a logic circuit board and depend upon additional software and hardware to perform the access control functions.
Note: All keypads have a circuit board that at a minimum changes each button press to an electrical signal (digitizes it into “1”s and “0”s).
A variation on the single entry point keypad is the multi-door keypad that can be wired to server or database in order to be part of a larger access control system having one or more keypads.
The standalone keypad (does not have to be connected to a database or internet) is self-contained, having a built-in logic board. These standalone keypads were originally designed for interior applications, having built-in NO/NC relays. When a button (key) is pushed, there is a connection to a momentary switch or a capacitance change in a non-mechanical capacitive keypad. When a programmed User Code is entered, the Fail Safe or Fail Secure electrified lock mechanism would either receive or have power eliminated, permitting access through the door. LEDs have been added to make programming and operation less complicated. Programming the standalone keypad is usually accomplished at the keypad.
The basic access control keypads vary by design and applications. For example, the standard commercially available keypads usually have a 12-button configuration, with three buttons side to side and four buttons up and down. Most keypads in the North American market look like a telephone keypad without the alphabet above eight of the numbers. However, this configuration requires sufficient width in order to have three buttons side to side.
For narrow stile aluminum door openings, or mullion equipped double doors, the mounting surface can be very narrow, so the number of buttons is usually two side to side and up to seven up and down.
Early standalone keypads performed just the unlocking function for a small number of users. The first keypads I remember buying were standalone models designed for interior application controlling a single door. These keypads contained the “brains.” They were programmed at the keypad using the pushbuttons and if memory serves, you could program maybe 10 to 20 User Codes. These keypads were 12volt AC or DC and they were equipped with a small relay. When a programmed User Code was entered, the keypad would unlock the electric strike or the electromechanical lock for a limited period of time, which was sometimes adjustable. Oh yeah and when power was lost, so were the user codes.
Standalone Keypads
Today’s standalone keypads have many more features available including managing hundreds of users, operate on a time date schedule and provide audit trail. They can provide complete access control functionality, which can include monitoring the door’s position, trigger a propped or forced door alert or have an alarm shunt. Some standalone keypads serve a dual function as they can also be networked. A keypad can be used to control just about every type of electrified lock hardware or trim.
There are specialty keypads for interior or exterior, vandal prone applications, harsh conditions and backlit keys. Some keypads are surface mounted, flush mount and mullion mount.
A standalone keypad can be a single component, for example Linear’s IEI brand 212i, a flush-mount telephone style keypad with three LEDs that is designed for lighter volume interior applications. The 212i has non-volatile EPROM memory and up to 120 one- to six-digit user codes. Audit trail is available as an option. This keypad is designed to install into a standard single gang electrical box. Add an electric strike or electrified lock and a power supply and you have a single door access control system.
A disadvantage of standalone keypads is depending upon the installation and wiring method, damaging the keypad can provide access to the wiring in order to gain unauthorized access.
Two-component products such as the Securitron DK-26 consist of a narrow stile keypad and a Central Processing Unit (CPU) logic board connected by a 16-foot cable. This configuration permits the CPU to be mounted away from the keypad for higher level of security. The DK-26 stainless steel keypad is weatherproof with true 10-button operation and up to 119 two- to seven-digit user codes.
For outdoor applications where a significant number of user codes are required, the SDC 925 Series Outdoor Digital Keypad has up to 480 one- to six-digit user codes that are programmed at the keypad. The keypad is designed for outdoor applications having die-cast metal keys and a heavy duty aluminum keyed lock enclosure. The SDC 925 offers audible and tactile feedback for programming and operation in addition to dual color status indicators. Two Form C relay outputs offer programmable activation and activation times. In addition, there are two open collector outputs. The Outdoor Digital Keypad offers Request-to-Exit input and time anti-passback. A door/gate sense input provides control of auto relock and door ajar.
Dual Credentials
Some keypads have dual credential capabilities. For example, the Sargent 4293 Standalone Prox Reader and Keypad offers all of the expanded capabilities of the Sargent Profile Series v.G1.5 lock hardware contained in a compact hard-wired reader designed for interior applications. The Sargent 4293 is a keypad with detachable proximity reader that provides standard access control functionality with its two Form C relays. The two inputs provide request to exit and door position. The proximity reader can be removed from the keypad and mounted up to a maximum of 10 feet away. The keypad and proximity reader can be mounted on opposite sides of a door, restricting access and egress using different credentials.
This dual-credential proximity reader and keypad offers a higher level of security when both are required to gain access. The UL 294 Listed Sargent 4293 can be used for standalone access control, or used as a reader as part of HID 125 KHz Weigand formats up to 40 bit. Up to 2,000 User Codes can be programmed and there is a 2,000-event audit trail.
The Sargent 4293 proximity keypad can be programmed at the keypad as well as from a personal computer using SofLink Plus Version 4.0 or higher software. The 4293 is equipped with infrared (IR) communications that allow the unit to be programmed with SofLink PDP software. No separate controller is needed for the 4293. This keypad includes HID proximity technology, a keypad, and the controller.
Alarm Lock offers several one- and two-credential digital access control keypads. These keypads are similar in shape to the Trilogy locks providing the end user with consistency in appearance and having the ability to offer a single manufacturer’s products. The DK3000 PIN Code keypad and the PDK3000 PIN/Prox ID Card Keypad have up to 2000 three- to six-digit user codes with multilevel security and a 40,000-event audit trail. These keypads have a real time clock enabling time scheduling according to time zones. They can be programmed at the keypad or personal computer.
For networked applications, Alarm Lock offers the Trilogy® Networx™ Wireless Keypads with NetPanel 2-Door Access Controller using PIN Code keypad and/or PIN/Prox ID Card Keypad. These networked keypads are hardwired to the controller and wireless from the controller to the gateway and computer. Features of Networx Keypads include global lockdown, passage mode, request-to-exit, door ajar and remote release options. The Alarm Lock keypads were introduced to provide end users the ability to operate electric strikes or magnetic locks and to offer an alternative for out opening doors.
The Prox ID card equipped keypads accept most HID proximity cards and key fobs. Users can be programmed to use a card only, code only or for a higher level of security, both card and code.
Sargent 4293 Installation
For this article, I was invited to the installation and wiring of a Sargent 4293 onto a hollow metal doorframe in the Dugmore & Duncan electronics lab and classroom in Corona, CA. The opening is equipped with a Norton 1601 BFXSN door closer, having a 3 to 6 power sizing.
A Sargent Exit Device with electric latch retraction, part number 56-8813F ETL 32D was installed using Rivnut fasteners to secure the device to the door. An electrification upgrade is available for the three-foot Sargent 80 Series Exit Devices. The kit for the three-foot exit device is Part Number R56AF.
A Securitron BPS-24-3, a three Amp, UL Class 2 listed, linear power supply that provides 24VDC filtered and regulated power was mounted onto the wall adjacent to the door. To run the wiring from the power supply and the keypad to the exit device, a McKinney QC Concealed Circuit Electric Hinge was installed. The McKinney electric hinge began as a model T4A3386, a 4.5” by 4.5”stainless steel ball bearing hinge. This eight-position electrified hinge is rated at 4 Amps continuous @ 24VDC.
The Sargent 4293 has five wires: red, black, blue, green and gray. The red wire is positive (+). The black wire is negative (-). The blue wire is the Main Relay C. The green wire is Main Relay N/O. The gray wire is Main Relay N/C. Since power is required to retract the rim latch, the Normally Open relay was wired to provide power for latch retraction.
A short raceway was drilled through this non-fire rated door from the center hinge wiring entry point to a point directly beneath the exit device bar mounting plate. Two Rivnuts were installed into the face of the door for securing the end cap mounting plate and strengthening the installation.
When the installation was completed, a few proximity cards were programmed in order to test the operation.
FMI
There are a variety of choices for keypads. Choosing the proper keypad for an application will not only make the end user happier, it should provide years of no problem operation.
For more information, contact your local locksmith distributor or
Alarm Lock: www.alarmlock.com
Linear: www.linearcorp.com/iei_access_solutions.php
Sargent: www.sargentlock.com
SDC: www.sdcsecurity.com/
Securitron: www.securitron.com
To read additional Locksmith Ledger articles on keypads, visit http://tinyurl.com/keypad312.
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