From the Lufft WS product family of professional intelligent measurement transducers with digital interface for environmental applications.

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WS303 UMB Compact Weather Station

Key features

  • All-in-one housing concept of a compact weather sensor combining several measurement parameters in one housing with only one cable connection
  • Integrated Kipp & Zonen CMP3 Pyranometer, which is tiltable
  • Built-in data pre-processing, universal interfaces and selectable output protocols
  • Maintenance-free operation – no moving parts that can wear out
  • Compatible with many commercially available Met/HydroMet data loggers and PLS systems thanks to an open communication protocol
  • Suitable for all climate zones; also for solar-powered automatic meteorological stations
  • Ventilated temperature and humidity measurement according to WMO guidelines
  • Integrated heater that can be switched on if there is danger of frost

The WS303-UMB Smart Weather Sensor for measuring of air temperature, relative humidity, solar radiation, and air pressure. Relative humidity is measured by means of a capacitive sensor element; a precision NTC measuring element is used to measure air temperature. The world renowned technology of Kipp & Zonen CMP3 is integrated. Measurement output can be accessed by the following protocols: UMB-Binary, UMB-ASCII, SDI-12, MODBUS. One external temperature or rain sensor is connectable.

Technical specification


Principle NTC
Measuring Range -50...60°C
Accuracy ±0,2°C (-20°C...+50°C), otherwise ±0.5°C (>-30°C)

Relative Humidity

Principle Capacitive
Measuring Range 0...100% RH
Accuracy ±2% RH


Response Time (95%) < 18s
Non-stability (change/year) < 1%
Non-linearity (0 to 1,000 W/m²) < 1%
Directional error (at 80° with 1,000 W/m²) < 20 W/m²
Temperature dependence of sensitivity < 5% (-10 bis 40°)
Tilt error (at 1000 W/m²) < 1%
Spectral range (50% points) 300 to 2,800nm
Measuring range 1400 W/m²
Altitude 0...60°
Azimuth -10°...10°

Air Pressure

Principle MEMS Capacitive
Measuring Range 300...1200 hPa
Accuracy +/- 0.5 hPa (...+40°C)

General Information

Heating 20VA at 24VDC
Interface RS485, 2-wire, half-duplex
Operating Power Consumption 4....32 VDC
Operating Humidity Range 0...100%
Operating Temperature Range -50...60%°C