The **FLM-CD-R** is an addressable relay module (Control Dual Relay) commonly used in intelligent fire alarm systems, specifically those utilizing the Bosch digital communication protocol. ### 1. Functional Overview The module provides two independent Form C (SPDT) relay outputs that are controlled by the fire alarm control panel (FACP). It allows the system to interface with external equipment such as elevators, HVAC fans, fire doors, and dampers. --- ### 2. Key Electronic Specifications The internal circuitry is designed for low power consumption and high reliability. | Parameter | Specification | | :--- | :--- | | **Operating Voltage** | 24 VDC (Nominal) | | **SLC Current Consumption** | 0.55 mA (Standby) | | **Relay Contact Rating** | 2.0 A @ 30 VDC or 0.5 A @ 125 VAC | | **Interface Protocol** | Bosch LSN (Local Security Network) | | **Wiring Class** | Class A or Class B (Style 4, 6, or 7) | --- ### 3. Core Electronic Components The module consists of several critical stages: #### A. Microcontroller & Communication Chip * **The LSN Controller:** Manages the digital handshake with the main fire panel. It decodes the unique address assigned to the module and monitors for "Set" or "Reset" commands. * **Addressing Logic:** Features rotary switches or digital programming capabilities to set a unique address (001–254) on the data loop. #### B. Relay Mechanism * **Dual Form C Relays:** Physical electromechanical switches. * **Form C Configuration:** Each relay has a Common (C), Normally Open (NO), and Normally Closed (NC) terminal. * **Isolation:** The electronic trigger circuit is optically or magnetically isolated from the load side to prevent high-voltage spikes from damaging the SLC loop. #### C. Supervisory Circuitry * **Internal Monitoring:** The module continuously monitors its own internal health and the status of the relays. * **Status LED:** A built-in LED (typically bi-color) indicates polling status (green) or an active/alarm state (red). --- ### 4. Wiring Interface The module typically features a terminal block for easy integration: ```markdown Terminal | Description ---------|------------------------------------ SLC In | Connection from the Control Panel Loop SLC Out | Connection to the next device in the loop Relay 1 | NO, C, NC contacts for first output Relay 2 | NO, C, NC contacts for second output ```