Door position monitoring devices provide status of a door (door is ope n or closed) to the access control system, allowing it to engage locks, annunciate alarm conditions, and other actions that provide security.
For example, an authorized user ma y access a door and pr op it op en, allowing the unauthorizedd entry of other people and/ or the removal of property .
A door position monitoring will detect the opening of the door upon the presentation of a valid credential (card), which starts a timer within the access system for perhaps 20 or 30 seconds.
When the door position device indicates that the door has shut, the access system can be set to re lock the door control mechanism. If the door is propped open past the timer duration, local and remote alarm signals can be set off an d tr an smitted.
The door contact is the most common type of door position indication. These contacts ca n be magnetic or mechanical, surface mounted or concealed, and are typically wired into the access control panel.
Any type of door contact can be used for this function, but it is important that this device’s contacts be used only for the door position function,
and not also connected to the intrusion detection system.
If only install one contact set on a door is allowed, DPDT (double pole double throw) contacts are available that provide two electrically separate contacts, one for the access system and one for the intrusion system.
In cases where it is difficult to install a door contact, door status can be achieved by installing specific door strikes or wired hinges that include a do or status output.
Status is built in to the locking device. Using these devices can reduce the cost of a system, because they can make the installation of a separate contact unnecessary.
Built-in devices are useful when installing an access system on a fire-rated door. Drilling holes in the fire door for the mounting of a contact set magnet may violate the door’s fire rating integrity .
Whether a separate contact or an output from the locking device, door status devices are typically installed on each access-controlled door.