Door contacts are electromagnetic components that monitor the closed/ open status of the door being controlled. These components consist of a pair of electromagnets. Typically these electromagnets are located at the top of the door with the passive magnet installed on the door and the electrified magnet installed on the doorframe. The magnets align with each other creating a magnetic field between them. When the door is closed, the magnets are aligned and the magnetic field is undisturbed. This position notifies the system that the door is closed. When the door is ajar, the magnetic field is disturbed and the system is notified that the door is unsecured.
Request-to-exit (REX) monitors activity immediately inside of a controlled door sensing that someone is approaching the controlled door from the inside and allows them to exit without activating an alarm. The door controller has an input for each door for the REX. When the REX push button is tripped, the door is then open or unlocked.