The **FLM-420-RLV1-S** (often referred to in series shorthand as FLM-44-R types) is an **Octo-relay Interface Module** typically used in Bosch fire alarm systems (LSN improved version). It is designed to provide multiple physical relay outputs for controlling external equipment. --- ## 1. Technical Specifications The following table outlines the key electronic parameters for this module: | Parameter | Specification | | :--- | :--- | | **Input Voltage** | 15 V DC to 33 V DC (LSN part) | | **Max. Current Consumption** | Approx. 6.35 mA (at 24 V DC) | | **Number of Relays** | 8 (Octo-relay) | | **Contact Rating** | 2 A @ 30 V DC / 0.5 A @ 125 V AC | | **Interface** | LSN (Local Security Network) | | **Operating Temperature** | -20 °C to +65 °C | --- ## 2. Core Electronic Components ### A. The Relay Array The module features eight independent change-over (Form C) relays. These are mechanical switches controlled electronically by the fire panel. * **Isolation:** The relays provide galvanic isolation between the fire panel's internal logic and the external load (e.g., elevators, fire doors, fans). * **Switching Capacity:** Designed for low-voltage signal switching rather than high-current power distribution. ### B. Addressing Switches (Rotary Switches) The module uses three rotary switches to define its unique address on the LSN loop. * **Manual Addressing:** You can set the address from 001 to 254. * **Auto-Addressing:** If set to 000, the fire panel automatically assigns an address. ### C. LSN Controller Chip The "brain" of the module is an integrated circuit (IC) that communicates with the Fire Alarm Control Panel (FACP). It handles: * **Data Transmission:** Receiving commands to trigger specific relays. * **Status Monitoring:** Reporting the health and connectivity of the module back to the panel. --- ## 3. Terminal Connections The module's PCB includes specific terminals for wiring: 1. **LSN Terminals:** `LSN a1/b1` and `LSN a2/b2`. These carry both power and data from the fire panel loop. 2. **Relay Terminals:** Each relay has three contacts: * **NC** (Normally Closed) * **C** (Common) * **NO** (Normally Open) --- ## 4. Key Features * **Fail-Safe Mode:** The module can be programmed to maintain its current state or switch to a predefined state if communication with the panel is lost. * **LED Indicators:** Typically features an integrated LED to signal communication status or internal faults. * **DIN Rail Mounting:** The internal PCB is usually housed in a casing compatible with standard 35mm DIN rails.