The **FLM-EB-R** and **FLM-EB-Q** are electronic end-of-line (EOL) modules used within fire alarm systems, specifically designed for use with the **Bosch LSN (Local Security Network)**. These modules ensure the integrity of a notification appliance circuit (NAC) or a monitored zone. ### Overview of Functionality These modules act as active termination points. Unlike simple resistors, they provide sophisticated monitoring and feedback to the fire alarm control panel. | Feature | FLM-EB-R (Resistor) | FLM-EB-Q (Quartz/Active) | | :--- | :--- | :--- | | **Primary Use** | End-of-line monitoring for conventional zones. | End-of-line monitoring for high-security or specific digital signaling. | | **Circuit Type** | 2-wire / 4-wire conventional lines. | LSN (Local Security Network) loops. | | **Detection** | Wire breaks and short circuits. | Precise impedance monitoring and digital addressing. | --- ### Key Electronic Components and Specifications The internal circuitry of these modules is miniaturized to fit within small housings or flush-mount boxes. #### 1. Monitoring Circuitry The modules contain precision resistors or integrated circuits (ICs) that create a specific electrical signature. * **Quiescent State:** The module draws a tiny, constant current. * **Alarm State:** When a detector triggers, the impedance changes, signaling the panel. * **Fault State:** If the wire is cut (Open Circuit) or crossed (Short Circuit), the module’s signature disappears, triggering a trouble signal. #### 2. Technical Specifications Typical electrical characteristics for the FLM-EB series include: | Parameter | Value (Typical) | | :--- | :--- | | **Operating Voltage** | 15 V DC to 33 V DC (via LSN) | | **Current Consumption** | < 1 mA | | **Housing Material** | ABS Plastic (Flame retardant) | | **Protection Class** | IP 30 | --- ### Installation and Wiring The electronic parts are designed for easy integration into the terminal base of a detector or a separate junction box. * **Terminal Blocks:** Screw terminals for secure connection to the signaling line. * **Polarity:** Most electronic EOL modules are polarity-sensitive. Reversing the wires will result in a "Trouble" or "Fault" condition at the panel. * **Addressing:** While some EOLs are passive, the Bosch "Q" versions often interact with the LSN bus to provide a specific digital heartbeat. --- ### Comparison with Standard Resistors Standard fire systems use a simple carbon-film resistor at the end of the line. The **FLM-EB-R/Q** series is superior because: 1. **Tamper Resistance:** It is harder to bypass the monitoring circuit with a simple jumper wire. 2. **LSN Integration:** It communicates directly with the Bosch digital protocol, allowing the panel to identify exactly which branch of a circuit has failed.