Honeywell MMF-301 Fire Alarm Monitor Module Class B 2-Wire

The Fire-Lite MMF-301 is an addressable mini monitor module designed for intelligent, two-wire SLC (Signaling Line Circuit) fire alarm systems. It provides a supervised, two-wire Class B initiating device circuit (IDC) for normally open contact fire alarm and security devices, including manual pull stations, heat detectors, conventional smoke detectors, gas detectors, flow sensors, and pressure sensors. Its uniquely compact footprint — just 1.3″ H × 2.75″ W × 0.65″ D — allows installation directly in a single-gang junction box immediately behind the monitored device without requiring rigid mounting hardware, making it an ideal solution for concealed or space-constrained installations. Address selection is performed via onboard rotary switches, and the module is backward compatible as a direct replacement for the earlier M301 module in existing Fire-Lite systems.

Key features & benefits

• Addressable Two-Wire Architecture — Operates on an intelligent two-wire SLC loop; each module carries its own unique address set via rotary switches, enabling precise point identification at the control panel without additional wiring infrastructure.
• Class B IDC for Normally Open Contacts — Provides a supervised two-wire Class B initiating device circuit terminated with a 47 kΩ end-of-line resistor, enabling reliable monitoring of normally open dry-contact devices such as manual pull stations, heat detectors, flow switches, and pressure sensors.
• Ultra-Compact Form Factor — At only 1.3″ H × 2.75″ W × 0.65″ D with 6″ minimum wire leads, the MMF-301 fits directly in a single-gang junction box behind the monitored device, eliminating the need for a dedicated 4×4 back box and reducing both labor time and conduit fill.
• Lightweight, No-Rigid-Mount Installation — The module's small size and light weight allow it to be suspended on its own lead wires within the junction box, simplifying retrofit and new construction installations in tight spaces such as above ceilings and inside device back boxes.
• Backward Compatible M301 Replacement — The MMF-301 is designed to replace an M301 module in existing Fire-Lite systems, protecting prior infrastructure investments and simplifying system upgrades or module replacements during maintenance cycles.
• Wide Operating Environment — Rated for temperatures from 32°F to 120°F (0°C to 49°C) and humidity from 10% to 93% non-condensing, suiting commercial, institutional, and light-industrial indoor environments.