The **FLM-CB-R** (often associated with Bosch Fire Alarm Systems) is an **Interface Module** designed to provide a supervised relay output for controlling external equipment, specifically within a Local Security Network (LSN) environment. Below is a detailed breakdown of its electronic components, specifications, and functions. --- ## 1. Core Technical Specifications The device acts as a bridge between the digital fire panel bus and high-current electrical systems. | Specification | Details | | :--- | :--- | | **Input Voltage** | 15 V DC to 33 V DC (via LSN) | | **Current Consumption** | Max. 1.7 mA (active/idle) | | **Relay Type** | 1 Form C (Changeover) | | **Contact Rating (Resistive)** | 5 A at 30 V DC / 5 A at 250 V AC | | **Contact Rating (Inductive)** | 2 A at 30 V DC / 2 A at 250 V AC | | **Protection Class** | IP 30 (standard housing) | --- ## 2. Key Electronic Components The internal PCB (Printed Circuit Board) consists of several critical subsystems: ### A. LSN Bus Interface * **ASIC/Microcontroller:** A specialized Integrated Circuit that manages communication with the Fire Alarm Control Panel (FACP). It handles addressing and status reporting. * **Isolation Circuitry:** Protects the rest of the LSN loop if the specific module fails or experiences a short circuit. ### B. Electromechanical Relay * **The Relay Coil:** Driven by a small transistor triggered by the onboard logic. * **Form C Contacts:** Includes a Common (C), Normally Open (NO), and Normally Closed (NC) set of pins. This allows the module to either complete or break a circuit upon activation. ### C. Supervision Circuitry * **EOL Resistors:** The module often requires End-of-Line resistors to monitor the integrity of the output wiring, detecting open circuits or short circuits. * **Feedback Logic:** Sends a signal back to the panel to confirm the relay has successfully switched states. --- ## 3. Terminal Connection Layout The module typically features a block of screw terminals for field wiring. | Terminal Label | Function | Description | | :--- | :--- | :--- | | **LSN (a1/b1, a2/b2)** | Data Loop In/Out | Connection to the fire panel's data bus. | | **C (Common)** | Pole | The central feed for the relay. | | **NO (Normally Open)** | Trigger Output | Closes when the alarm is activated. | | **NC (Normally Closed)** | Fail-Safe Output | Opens when the alarm is activated. | --- ## 4. Operational Logic 1. **Addressing:** The module is assigned a unique address via rotary switches or electronic programming. 2. **Monitoring:** The electronic logic constantly monitors the LSN bus for a "Trigger" command. 3. **Action:** When a command is received, the internal transistor energizes the relay coil, moving the physical contact from NC to NO. 4. **Feedback:** The module reports the physical state of the relay back to the main control panel for safety verification.