Premises Control Unit(PCU) or Panel:The "Brain" of the system, reads sensor inputs, tracks arm/disarm status, and signals intrusions. In modern systems, this is typically one or more computer circuit boards inside a metal enclosure, along with a power supply.
Sensors:In devices which detect intrusions, Sensors may placed at a perimeter of the protected area, within it, or both. Sensors can detect intruders by a variety of methods, such as monitoring doors and windows for opening, by monitoring unoccupied interiors for motions, sound, vibration, or other disturbances.

Premises Control Unit(PCU) or Panel:The "Brain" of the system, reads sensor inputs, tracks arm/disarm status and signals intrusions.In modern systems, this is typically one or more computer circuit boards inside a metal enclosure, along with a power supply.
Sensors:In devices which detect intrusions, Sensors may be placed at a perimeter of the protected area, within it, or both.Sensors can detect intruders by a variety of methods such as monitoring doors and windows for opening, by monitoring unoccupied interiors for motions, sound, vibration, or other disturbances.
Alerting Devices:These indicate an alarm condition, most commonly these are bells, sirens, and/or flashing lights.Alerting devices serve the dual purposes of warning occupants of intrusion, and potentially scaring off burglars.
Keypads:Small devices, typically wall-mounted, function as the human-machine interface to the system.In addition to buttons, keypads typically feature indicator lights, a small mulch-character display, or both.