The typical components of an alarm system include the master control panel, keypad and several sensors. Sensors include door, window and infrared types. Window and door sensors typically trigger the alarm when electrical contact breaks by actions such as opening a door. Infrared sensors are usually body heat.
The master control panel is the brain of the alarm system. It interprets information from sensors and the keypad to determine when to call the monitoring company or sound the alarm. This panel is generally located out of the way in a closet or the basement with hardwired alarm systems.
The keypad is an input device where individuals entering the home or business input a security code to turn off the alarm or set it to detect intruders. Keypads often have a panic button that immediately sounds the alarm or calls the monitoring company for help. The keypad gives a limited amount of time for entering the code to disarm the system before calling for help, so installers normally locate it near the door the family uses most, such as the entry from the garage into the home. Often homeowners prefer to pay the additional cost to install a keypad at other entry doors or in the master bedroom for additional convenience.