Query the Access Control Expert

Oct. 27, 2008
System Integration: Simple or Complex?

Specific Examples
When it comes to access control, is system integration as simple as connecting devices? Can you give examples?

A: In some systems, outputs (relays or voltage outputs) can be programmed to react to inputs (opens or closures on a circuit) or events (credential use). In others, systems send data over a serial or Internet connection to communicate with another device. These capabilities can be used to control another device, such as a camera or a heating ventilation and air conditioning (HVAC) system.

Rarely, at a minimum, some programming will be required to tell the reacting system what to do when the initiating event occurs. The communications protocol or language used in the two systems may not be the same, so a device to translate between the systems may be required. For this reason, the most common way to integrate systems is with a direct connection from a relay output of the access control system to an input of the other system.

You can use CCTV, for example, to supplement an entry system by allowing an operator to visually identify a user before access is granted. CCTV can also be used to record an entry or record activity before or after an event. By connecting the two systems, switchers can be controlled to focus on appropriate cameras and pan tilt controls can be repositioned to view the location of the controlled door or monitored location. The interconnection can also let the CCTV system know to preserve a record of activity.

Reasons to Integrate HVAC and Fire Systems
What are some common reasons to integrate access control and HVAC systems? How about fire alarm systems?

A: Considerable costs of heating, air conditioning and energy savings can be achieved by turning off or setting back the system when it is not occupied. Connecting the access control system to the HVAC system will allow you to turn on or return the system to a setting that is comfortable when a credential is used. Also, because the user is identified in the access system, the specific user can be billed for the extra after hours energy use.

As far as fire systems, the use of some types of locks or locking some doors will require that the door be unlocked in the event of a fire alarm. This will require you to integrate or interconnect the fire alarm with the access control system. Fire codes and common sense requires that this connection be very reliable.

If you decide to make this connection with a serial or Internet connection or to utilize a part of either system that will require programming, make sure that both systems have been tested and approved for this type of operation. The most reliable way to make sure doors unlock when the fire alarm activates is to directly break the power to the fail safe lock or directly supply power to the fail secure lock. The more devices that you rely on to accomplish this, the more possibilities there are for failure.