The **HMS-1-R** is a specific model of a **Manual Pull Station**, typically used in fire alarm and emergency systems. Specifically, it is a high-quality, addressable pull station often associated with brands like **Siemens (Cerberus Division)**. --- ### ## Technical Specifications Overview The "R" in the suffix usually denotes a specific feature set (such as "Reset" capabilities or "Red" housing), and the "HMS" series is known for its integration with intelligent fire alarm control panels. | Feature | Specification Details | | :--- | :--- | | **Device Type** | Addressable Manual Pull Station | | **Communication Protocol** | Digital (e.g., Siemens H-Series / FDLC) | | **Operating Voltage** | 18VDC - 31VDC (Loop Powered) | | **Current Consumption** | ~1mA (Active/Standby) | | **Installation** | Single-gang or surface mount | | **Material** | High-impact polycarbonate / Metal Alloy | --- ### ### Key Electronic Components The HMS-1-R is not a simple mechanical switch; it contains sophisticated circuitry to communicate with a fire panel. 1. **Integrated Microprocessor:** * The core of the unit is a small microcontroller that handles data encoding and decoding. * It monitors the state of the internal switch and reports status changes back to the control panel. 2. **Addressing Module:** * Unlike conventional pull stations, this has an electronic address. * **Programming:** It is typically programmed using a device like the DPU (Device Programming Unit) to assign a unique ID on the loop. 3. **Status LED:** * Usually contains a bi-color LED (Red/Green) to indicate "Normal" polling or "Alarm" status. 4. **EEPROM Memory:** * Internal non-volatile memory stores the device’s unique serial number and its assigned loop address. 5. **Isolation Circuitry:** * Some versions include built-in short-circuit isolators to ensure that a fault in one station doesn't take down the entire data loop. --- ### ### Wiring Configuration Because it is an addressable device, it is wired in a **Signaling Line Circuit (SLC)** loop. ```yaml Terminal 1: Positive (+) Loop In/Out Terminal 2: Negative (-) Loop In/Out Terminal 3: Ground (Earth) - For shielding/drain wire ``` --- ### ### Operational Logic 1. **Quiescent State:** The microprocessor periodically sends a "Healthy" signal to the fire alarm control panel (FACP). 2. **Activation:** When the lever is pulled, a physical microswitch closes. 3. **Signal Processing:** The microprocessor detects the switch closure and sends an interrupt or a high-priority digital code to the FACP. 4. **Reset:** The device must be mechanically reset (usually with a key or hex tool) to open the switch and allow the FACP to clear the alarm.