Using Controller Area Network, it CAN be done
Considering how reliant on new technology our industry is becoming, it is perhaps surprising that the fundamental architecture of a door access control system has not really changed in the past 25 years. In essence, the system architecture remains as it was in 1977 when CardKey launched the first in what was then a "new" generation of card access systems. The system has incorporated little technological change since, when it is comprised of a door controller (a microprocessor-based circuit board and a power supply) servicing two card readers, and one or two doors.

Today, a PC running a Windows program can be connected to access control panels that have the capacity to accommodate four or even eight doors. However, the system's inherent limitations remain. For example, a multi-door application will throw up a number of system design issues for the security installer.

Careful thought needs to be given with regard to the siting of access control equipment (the PCs, door controllers and readers) keeping in mind that the end-user requires an installation which is both aesthetically acceptable and is capable of integrating with the building and its users with the minimum of disruption.

Clearly, a large access control installation requires a significant amount of hard work for it to be accommodated into the building infrastructure. A typical installation will require all the door hardware and data cabling as well as enclosures containing control panels and power supplies, to be situated as unobtrusively as possible. Once the computer network as well as fire alarm, air conditioning, telephone, intruder systems etc have been installed, few modern commercial premises have enough free closet space to mount access control enclosures.

So door controller enclosures are typically mounted within the ceiling void, close to the door. This practice is fine but makes subsequent service access difficult. But with office space at a premium, ceiling voids are becoming shallower, particularly so in new and refurbished buildings, excluding even this option.

Additionally changes to the interior layout of a building are frequently accompanied by the installation, or moving of, partition walls – a situation that can have far-reaching implications for access control installations. With inflexible legacy architecture, relocating and re-wiring control panels is no easy task.

The security installer must continuously be on the lookout for new technology that offers a more flexible approach, providing performance benefits to the end-user while delivering significant cost and installation time gains to the installer. Borer has employed CAN (Controller Area Network) technology to build access control systems that cut down on installation time and significantly reduce the amount of equipment deployed.

CAN technology was originally developed by the German company Robert Bosch for use in the automotive industry to provide a cost-effective communications buss and practical alternative to expensive and cumbersome wiring looms. CAN has subsequently been adopted by ISO as an open communication standard for intelligent devices and is now increasingly being used in industrial control and building automation systems. (It is estimated that over 100 million CAN-based devices were delivered worldwide in 2000). CAN is cost-effective, functions in a difficult electrical environment, offers high-speed communication and is easy to install and maintain.

Combining a CAN-based card reader network with an Ethernet and TCP/IP site network, we are able to install an enterprise-wide system which uses the Internet Protocol (IP) over the client's own network. Instead of having to install a number of traditional one, two or four-door controller panels, a CAN-based system uses just one site controller. Up to 250 devices (door access readers, alarm panels etc) can be connected to this over Controller Area Network.

Distributed intelligence
For the security installer CAN-based card readers have a number of advantages over traditional control panels with Wiegand or clock and data card reader heads. Not least of these is the distributed intelligence at every CAN-based proximity card reader, which effectively does away with the need for the traditional one, two or four door control panel. Additionally:

* Devices are 'Plug and Play' which ensures they can be installed onto a CAN network without special programming and with the minimum of fuss

* All hardware (door access readers, attendance terminals, alarm monitors) share the CAN network, thus less kit and no bespoke cabling is required to fulfill a project

* A CAN-based device takes less power: one power supply can support a number of doors in a typical CAN-based access control system. Also a legacy reader and controller will typically need 280mA at 12 volts DC, while the equivalent CAN-based reader controller needs only 90mA

* LAN technology allows for both electrical power and data to pass over the LAN. The whole job can be completed by the installer, instead of having to employ an electrician to connect power and an installer to set up the network, hence fewer power adapters and a more economical installation

* Fewer cables are required to terminate – a typical full-featured eight-door legacy system requires around 392 cable ends terminated, compared to just 160 using CAN.

In general, manufacturers and suppliers of security systems have been rather slow to incorporate networking technology, which provides the design flexibility that the security installer requires for 21st century access control projects. Installing control panel boxes around a building is both aesthetically unpleasant and costly in installation time and money.

It is time for evolution – we have all witnessed the technological advances that have produced proximity-based smart cards, biometric fingerprint recognition readers and high-speed networks. However until now this has taken place without any corresponding performance gains, or improvement in access control system architecture.