4-20 mA conductivity monitor and transmitter FLS M9.35 – M9.45

Modbus RTUwith temperature measurement

Product overview
The FLS M9.35 and FLS M9.45 are industrial conductivity monitor-transmitters for process and water treatment applications, including ultrapure water (UPW) systems. Both units measure and display conductivity, resistivity or TDS and provide continuous process control and analog transmission.

Key functional description
Multiple-parameter visualization (conductivity, resistivity, TDS). 4" transflective graphical display with high-brightness backlight for clear readability. Freely configurable cell constant for compatibility with any 2-cell conductivity probe. 4–20 mA analog output included for integration with control systems.

Differences between models

• FLS M9.45: includes Modbus RTU (RS-485) for remote data access and system monitoring, plus a digital SSR output for fast min/max alarm activation.
• FLS M9.35: essential configuration providing the same measurement capabilities and analog output but without Modbus RTU and without the SSR digital output.

Applications

• Water treatment and regeneration
• Industrial wastewater recovery and treatment
• Softening and filtration systems
• Desalination plants
• Demineralised / ultrapure water (UPW) production
• Reverse osmosis / EDI systems
• Cooling water monitoring
• Manufacturing process control
• Chemicals production

Main advantages of Modbus RTU

• Reduced wiring and installation costs
• Compatibility with international communication standards
• Reliable data transmission in industrial environments
• Remote configuration and diagnostics
• Scalable and cost-effective system integration

Main features

• Simultaneous visualization of Conductivity, Resistivity or TDS
• Configurable cell constant; compatible with any 2-cell conductivity probe
• Temperature compensation mode optimized for ultrapure water (UPW) applications
• Transflective 4" graphical display with backlight
• Conductivity input range: 0.055 ÷ 200000 μS/cm
• Conductivity measurement accuracy: ±2.0% of reading
• Supply voltage: 12–24 VDC ±10% (regulated)
• Maximum consumption: < 300 mA
• Analog output: 4–20 mA (both models)

Compatibility
FLS instruments support potentiometric and inductive conductivity probes, enabling use with a wide range of 2-cell sensor technologies.

Technical specifications

• Models: FLS M9.35 (basic), FLS M9.45 (with advanced connectivity)
• Displayed parameters: Conductivity, Resistivity, TDS
• Display: 4" graphical transflective display with high-brightness backlight
• Cell constant: freely configurable; compatible with any 2-cell conductivity probe
• Analog output: 4–20 mA
• Digital/communication: M9.45 includes Modbus RTU (RS-485); M9.35 without Modbus
• Alarm output: M9.45 includes digital SSR output for min/max alarms; M9.35 without SSR
• Conductivity range: 0.055 ÷ 200000 μS/cm
• Accuracy: ±2.0% of reading
• Temperature compensation: dedicated UPW mode
• Supply voltage: 12–24 VDC ±10% (regulated)
• Maximum consumption: < 300 mA
• Sensor compatibility: potentiometric and inductive 2-cell probes