Eaton MTL4850

Core Technical & Performance Parameters

• Hazardous Area Certification: Ex nA IIC T4 Gc (only when paired with MTL4842 slave units in Zone 2)
• Maximum Supported Slave Modules: Up to 8 x MTL4842 on single RS485 bus
• Total Max Field Instrument Capacity: 128 HART transmitters per MTL4850 master
• Host Communication Protocol: Modbus RTU RS485 standard industrial protocol
• RS485 Bus Operating Baud Rate: Configurable 1200 ~ 38400 baud
• Operating Ambient Temperature: -40°C ~ +70°C
• Input Power Supply: 24 VDC industrial control cabinet power, 150mA max consumption
• Diagnostic Functions: Slave module offline detection, bus communication error logging, channel fault aggregation
• Mounting: Standard 35mm DIN rail inside safe control cabinet

Functional Features

1. Central master unit to coordinate all MTL4842 Zone 2 slave multiplex modules
2. Converts aggregated multi-channel HART data to Modbus RTU for seamless DCS/SCADA integration
3. Full system-level diagnostic logging for slave module communication loss and field channel faults
4. Configurable Modbus register mapping for flexible host system data point assignment
5. Wide operating temperature range compatible with outdoor unheated control cabinet installations
6. Front panel LCD status display and push-button local configuration without software tools
7. Built-in bus surge protection to shield RS485 communication circuits from industrial transient voltage spikes

Working Principle

Material Composition

• Module Housing: Black anti-static V0 flame retardant ABS plastic
• Main Control PCB: FR4 high-temperature industrial grade printed circuit board
• Communication Interface Circuits: Isolated RS485 transceivers, gas discharge surge protection tubes
• Human Machine Interface: Monochrome LCD screen, tactile membrane push buttons
• Terminals: Nickel-plated copper screw terminals with PA66 flame retardant plastic housing
• Mounting Hardware: Zinc-plated spring steel DIN rail mounting clips

Structural Characteristics

1. Medium-width DIN rail module with integrated front LCD display and operation buttons
2. Three separated terminal zones: 24V DC power input terminals, Modbus host communication terminals, RS485 slave bus terminals
3. Multi-color front LED indicators for power, bus communication active status and system fault alerts
4. Removable transparent plastic terminal safety cover for wiring maintenance

Installation Requirements

1. Install inside non-hazardous safe-area control cabinets only
2. Vertical DIN rail mounting; maintain minimum 10mm vertical air gap above and below unit
3. RS485 slave bus cable routed separately from Modbus host communication cable, minimum 10cm separation
4. RS485 bus endpoints fitted with 120Ω termination resistors supplied with MTL4850
5. 24V DC power supply must provide short-circuit overload protection rated at 0.5A
6. Cabinet ventilation required for continuous operation above +60°C ambient temperature
7. All communication cable shielding grounded single-ended inside control cabinet protective earth bar

Application Scenarios

• Large-scale refinery Zone 2 HART instrument central data collection system
• Natural gas transmission compressor station multi-transmitter SCADA interface
• Petrochemical tank farm process monitoring Modbus gateway system
• Mining chemical processing plant Class I Div 2 instrumentation data aggregation
• Fertilizer manufacturing Zone 2 production line centralized HART data acquisition

Operation & Maintenance Precautions

1. Configure Modbus register mapping via front panel buttons before connecting host DCS/PLC systems
2. Maximum 8 MTL4842 slave units must not be exceeded per single MTL4850 master bus segment
3. Replace RS485 bus cable if continuous communication error faults persist after termination resistor inspection
4. Avoid installing unit adjacent to high-current AC contactors and variable frequency drives to reduce EMI interference
5. Perform full system communication diagnostic test every 6 months for critical process safety applications
6. Do not connect MTL4850 RS485 slave bus directly to Zone 0 intrinsically safe field instruments without MTL4842 interface
7. Keep cabinet internal humidity below 85% non-condensing to prevent LCD display fogging and PCB leakage current