A conventional Fire Alarm System employs one or more circuits, connected to sensors (initiating devices) wired in parallel. Fire Alarm System sensors are devised to dramatically decrease the circuit resistance when the environmental influence on any sensor exceeds a predetermined threshold. In this system, the information density is limited to the number of such circuits used. To facilitate location and control of fire within a building, the structure is subdivided into definite areas or zones
Addressable Fire Alarm System Addressable Fire Alarm System employ one or more Signaling Line Circuits, slang -usually referred to as loops or SLC loops - ranging between one and thirty. Depending on the protocol used, a Signaling Line Circuit can monitor and control several hundred devices. Each SLC polls all the devices connected Each device on a SLC has its own address, and so the panel knows the state of each individual device connected to it.