This plug-in loop expander module adds a second Signaling Line Circuit (SLC) to Notifier ONYX Series fire alarm control panels. On the NFS-640/NFS2-640, the LEM-320 expands the panel from one to two SLC loops. On the NFS-3030/NFS2-3030, each LCM-320 Loop Control Module supports one expansion LEM-320, allowing the panel to scale up to ten total SLC loops (five LCM-320s plus five LEM-320s).

Each SLC loop supports up to 12,500 feet (3,810 m) of wiring distance using 12 AWG twisted-unshielded pair in a Class B (Style 4) configuration. The module draws a maximum of 100 mA and includes built-in degraded mode operation to increase system survivability if the loop is compromised. Installation is straightforward, the LEM-320 plugs directly into the panel chassis with no additional mounting hardware.