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Addressable panels are usually much more advanced than their conventional counterparts, with a higher degree of programming flexibility and single point detection.


Panels usually have a number of signaling line circuit loops – usually referred to as loops or SLC loops – ranging between one and thirty. Depending on the protocol used, a loop can monitor and control several hundred devices. Some protocols permit any mix of detectors and input/output modules, while other protocols have 50% of channel capacity restricted to detectors/sensors and 1/2 restricted to input/output modules. Each SLC polls the devices connected, which can number from a few devices to several hundred, depending on the manufacturer. Large systems may have multiple SLCs, and SLCs are further divided into sub-groups through the use of fault-isolation modules.

Each device on a SLC has its own address, and so the panel knows the state of each individual device connected to it. Common addressable input (initiating) devices include:

  • Smoke detectors
  • Manual call points or manual pull stations
  • Notification appliances (Simplex systems with TrueAlert signals only)
  • Responders
  • Fire sprinkler system inputs
  • Switches
  • Flow control
  • Pressure
  • Isolate Standard switches
  • Addressable output devices are known as relays and include
  • (Warning System/Bell) Relays
  • Door Holder Relays
  • Auxiliary (Control Function) Relays
  • Relays are used to control a variety of functions such as Switching fans on or off
  • Activating fire suppression systems
  • Activating notification appliances
  • Shutting down industrial equipment
  • Recalling elevators to a safe exit floor
  • Activating another fire alarm panel or communicator.