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WS401-UMB Smart Weather Sensor

Make:  Lufft    Model:  WS401 UMB
✅ Compact all-in-one weather sensor, low power, aspirated radiation shield, open communication protocol.
✅ Measurand : Temperature, relative humidity, precipitation and air pressure.
✅ Principle Used : NTC/T, Capacitive/RH, Tipping bucket/Precipitation, MEMS capacitive/Pressure.
✅ Signal Output : RS485 with supported protocols UMB-Binary, UMB-ASCII, Modbus-RTU, Modbus-ASCII, XDR and SDI-12.
✅ Article number:8377.U01

From the WS product family of professional intelligent measurement transducers with digital interface for environmental applications. Integrated design with ventilated radiation protection for measuring: Air temperature, relative humidity, precipitation and air pressure. One external temperature sensor is connectable.

Advantages of the Smart Weather Sensor WS401:

  • All-in-one housing concept of a compact weather sensor combining 4 measurement parameters in one housing with only one cable connection
  • Built-in data pre-processing, universal interfaces and selectable output protocols
  • Suitable for all climate zones; also for solar-powered automatic meteorological stations
  • Ventilated temperature and humidity measurement according to WMO guidelines

Application of the Smart Weather Sensor WS401:

  • Weather observation for road and traffic control systems
  • Automatic weather station / Automatic weather sensor (AWS)
  • PV-Monitoring / Solar Monitoring on photovoltaic farms
  • Hydro-meteorological stations
  • Weather observation for building automation
  • Weather stations at airports, marinas and onboard ships
  • Integration into various other systems/solutions, where environmental data is needed…




General Specification



Ø ca. 150mm, height ca. 380mm


Approx. 1.5 kg


RS485, 2-wire, half-duplex

Power Supply

4 ..11…32 VDC, 5…11 VDC (electronics with limited precision of measurements), 24 VDC +/- 10% (heater)

Power Consumption

40 VA (heater)

Operating Temperature

-50…+60°C (with heater)

Operating Rel. Humidity

0…100% RH

Cable Length


Protection Level Housing


Mast Mounting Suitable For

Mast diameter 60 – 76 mm

Air Temperature

Principle: NTC
Measuring range: -50 … +60 °C
Unit: °C
Accuracy: ±0.2°C (-20 … 50°C), otherwise ±0.5°C (>-30°C)

Relative Humidity

Principle: Capacitive
Measuring range: 0 … 100 % RH
Unit: % RH
Accuracy: ±2% RH

Air Pressure

Principle: MEMS capacitive
Measuring range: 300 … 1200 hPa
Unit: hPa
Accuracy: ±0.5 hPa (0…40°C)


Resolution: 0.2 mm
Accuracy: ±2 %
Max. intensity: 360 mm/h

Precipitation with reduction ring

Resolution: 0.5 mm
Accuracy: ±2 %
Max. intensity: 144 mm/h