The FPE-1000-SLC Signaling Line Circuit Plug-in Module provides a Signaling Line Circuit (SLC) for connection of analog devices to the FPA-1000 Analog Addressable Fire Panels. It is mandatory equipment which installs at the top position on the main board in the fire panel. A second FPE-1000-SLC Plug-in Module can be installed as an option in the position below the first SLC board. The bottom position can be equipped with an optional FPE-1000-CITY City Tie Plug-in Module. The plug-in modules connect directly to the main board. Signaling Line Circuits can be wired as Class A Style 6 or 7 or Class B Style 4 circuits. Class A configuration is recommended because this allows the system to poll the circuit in both directions, ensuring circuit operation in the event of a single break in the wiring. Each SLC is power-limited and supervised.