Siemens MSI-20B 500-893081

Core Technical Specifications

• Trigger Mode: Dual-action (Push inner button first, then pull down main lever)
• Communication Protocol: Siemens proprietary addressable fire bus protocol, two-wire loop connection
• Address Storage: Built-in microchip stores unique device address and fault status data
• Mounting Method: Surface mount / semi-flush embedded wall mounting
• Overall Dimensions: 139.7 mm × 101.6 mm × 76.2 mm (5.5 × 4.0 × 3.0 inch)
• Net Weight: 0.42 kg
• Housing Material: Matte red flame-retardant polycarbonate plastic
• Operating Temperature: -10 °C ~ +60 °C
• Reset Mode: Open front cover with Allen wrench, reset internal trigger mechanism manually
• Compatible Control Panels: Siemens MXL, IXL/ICON-1, XL3 fire alarm host

Function & Performance Features

1. Dual-action two-step trigger structure, prevent accidental false alarm caused by casual collision or child misoperation
2. Intelligent addressable design, fire control panel accurately displays exact alarm location without manual patrol search
3. Real-time bus loop supervision function, automatically upload open circuit, short circuit and device fault signal to control panel
4. Trigger lever self-locking after activation, maintain obvious alarm visual indication until manual reset
5. High contrast raised white fire warning text on red housing, clear recognition under smoke and low light environment
6. Support DPU/FPI-32 portable programmer for on-site address setting and function testing

Working Principle

1. Two independent mechanical micro switches inside the unit, only both switches are triggered simultaneously to send fire alarm signal
2. Built-in single-chip microcomputer encodes unique device address and alarm state signal, transmits to fire panel via two-wire bus
3. Fire control panel receives address signal to display specific building floor/room alarm position, trigger fire linkage equipment
4. When bus circuit has open/short fault, internal chip sends fault code to host for maintenance reminder
5. After alarm trigger, mechanical spring locks pull lever down to retain visual alarm mark until cover is opened for reset

Material Composition & Structural Characteristics

• Outer Housing: Injection molded flame-retardant PC polycarbonate, impact resistant, UV aging resistant for indoor long-term use
• Trigger Mechanism: Stainless steel spring and metal lever assembly, rust-proof and long service life
• Internal Circuit Board: SMD anti-interference PCB with conformal coating, moisture-proof for basement humid environments
• Locking Component: Standard hexagonal Allen key lock to prevent unauthorized random reset

Installation Requirements

1. Install at height 1.2–1.5 m above ground, standard human hand operation height specified by fire protection code
2. Two-wire fire bus cable connected to internal terminal block, positive and negative polarity cannot be reversed
3. Surface mounting requires reserved wall bottom box; semi-flush installation needs pre-embedded wall box during building construction
4. Avoid installation positions blocked by cabinets, doors and other obstacles, ensure easy access in fire emergency

Application Scenarios

• Commercial shopping mall public passage fire alarm
• Office building corridor and stairwell fire safety monitoring
• Hotel guest floor and public area fire protection system
• Hospital ward and medical building fire linkage system
• School teaching building and student dormitory fire alarm

Usage Precautions

1. Regular monthly inspection of trigger lever flexibility, eliminate stuck failure caused by dust accumulation
2. Do not paint the housing surface during building decoration, will block warning text and trigger structure
3. After fire alarm activation, use matched Allen wrench to reset before resuming normal monitoring function
4. Avoid installation near water sprinkler nozzle to prevent long-term water mist corrosion internal circuit board