The controlling component of a fire alarm system is the addressable control panel.  The panel receives data from devices that detect and report fires, monitors their operation. It allows for automatic equipment management and transfer of information needed to prepare the facility for a fire.

Any related initiating device, notification appliance, control, transmitter, or relay may receive electrical energy from the panel.

One or more Signaling Line Circuits (SLC loops) ranging from one to thirty are used in an addressable fire alarm control panel. A Signaling Line Circuit can monitor and control hundreds of devices depending on the protocol used.

Some protocols allow for the use of any combination of detectors and input/output modules. Other protocols, on the other hand, allocate 50% of channel capacity to detectors/sensors and 50% to input/output modules.

Depending on the manufacturer, each SLC polls the linked devices, which can range from a few to several hundred. Multiple Signaling Line Circuits may be present in large systems.