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CWS220 900 MHz Wireless Infrared Radiometer
Cable-Free Sensor
Wireless network means flexibility, cost savings, time savings
weather applications water applications energy applications gas flux & turbulence applications infrastructure applications soil applications


The CWS220 is a wireless version of our SI-111 infrared radiometer. It measures the surface temperature of an object without physical contact. This radiometer has an internal 900 MHz spread-spectrum radio that transmits data to a CWB100 Wireless Base Station or to another wireless sensor. The frequency of the CWS220's internal radio is commonly used in the US and Canada.

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Benefits and Features

  • Provides road surface, plant canopy, soil surface, snow surface, and water surface temperature measurements
  • Internal frequency-hopping, spread-spectrum radio provides longer range and less interference
  • Battery powered
  • A reliable, low-maintenance, low-power method for making measurements in applications where cabled sensors are impractical or otherwise undesirable
  • Transmissions can be routed through up to three other wireless sensors
  • Measures surface temperature continuously in the field
  • Ideal for providing spatial averages
  • Compatible with CR800, CR850, CR1000, and CR3000 dataloggers

This product will be discontinued as of 10 April 2017. Please review the CWS-Series and CWB-Series Discontinuation Notice for further details. 


Detailed Description

The CWS220 includes a thermopile, which measures surface temperature, and a thermistor, which measures sensor body temperature. The two temperature sensors are housed in a rugged body that contains a germanium window. It is battery powered using either alkaline batteries or a rechargeable battery and a solar cell.

The CWS220 can route its transmissions through up to three other wireless sensors. A datalogger is connected to the CWB100 base station for processing and storing its data. The CWS220 interfaces with a PC for configuration via the A205 CWS Sensor to PC Interface.

The calibration coefficients used for determining the target temperature by means of the Stefan-Boltzman equation are stored in the CWS220 at the time of calibration.

Why Wireless?

There are situations when it is desirable to make measurements in locations where the use of cabled sensors is problematic. Protecting cables by running them through conduit or burying them in trenches is time consuming, labor intensive, and sometimes not possible. Local fire codes may preclude the use of certain types of sensor cabling inside of buildings. In some applications measurements need to be made at distances where long cables decrease the quality of the measurement or are too expensive. There are also times when it is important to increase the number of measurements being made but the datalogger does not have enough available channels left for attaching additional sensor cables.

Note: The internal radio is not designed to move a lot of data quickly. It takes 15 to 30 seconds per hop when moving data from a sensor, through a sensor used as a repeater, and ending up at the base radio. Going through three repeaters could take a data packet anywhere from 45 to 90 seconds to get to the base radio.


Weather Resistance IP67 rating for sensor and battery pack (Battery pack must be properly installed. Each sensor is leak tested.)
Operating Temperature Range -25° to +50°C
Operating Relative Humidity Range 0 to 100%
Power Source 2 AA batteries with a battery life of 1 year assuming sensor samples taken every 10 minutes. (Optional solar charging available.)
Average Current Drain 300 μA (with 15-minute polling)
Response Time < 1 s (to changes in target temperature)
Target Temperature Output Signal 60 μV per °C difference from sensor body
Body Temperature Output Signal 0 to 2500 mV
Optics Germanium lens
Wavelength Range 8 to 14 μm (Corresponds to atmospheric window.)
Field of View (FOV) 22° half angle
Absolute Accuracy
  • ±0.2°C (-10° to +65°C)
  • ±0.5°C (-40° to +70°C)
  • ±0.1°C (-10° to +65°C)
  • ±0.3°C (-40° to +70°C)
  • ±0.05°C (-10° to +65°C)
  • ±0.1°C (-40° to +70°C)
Dimensions 15 x 6 x 4.5 cm (5.9 x 2.4 x 1.77 in.)
Weight 270 g (9.6 oz)

Internal 25 mW FHSS Radio

Frequency 902 to 918 MHz
Where Used US and Canada
FHSS Channel 50
Transmitter Power Output 25 mW (+14 dBm)
Receiver Sensitivity -110 dBm (0.1% frame error rate)
Standby Typical Current Drain 3 μA
Receive Typical Current Drain 18 mA (full run)
Transmit Typical Current Drain 45 mA
Average Operating Current 15 μA (with 1-second access time)
Quality of Service Management RSSI
Additional Features GFSK modulation, data interleaving, forward error correction, data scrambling, RSSI reporting



The CWS220 mounts to a mast or pole via the the 26054 bracket. It is mounted at an appropriate distance from the target where it can measure an individual leaf, a canopy, or any surface of interest. Because the CWS220 is wireless, it can be mounted in many locations that would be problematic for a cabled sensor.

Datalogger Considerations

Compatible Dataloggers

CR200(X) Series CR800/CR850 CR1000 CR3000 CR5000 CR7X CR9000X CR6

Note: The CR6 datalogger must have datalogger OS version 4.0 or higher.


CWS220 Firmware v.5 (442 KB) 03-30-2016

Latest firmware for the CWS220.  

View Update History

Wireless Sensor Planner v.1.7 (30.5 MB) 08-08-2013

The Wireless Sensor Planner is a tool for use with Campbell Scientific wireless sensors.  It assists in designing and configuring wireless sensor networks.

Frequently Asked Questions

Number of FAQs related to CWS220: 2

  1. An A205 is required to write the radio address of the wireless base station to the wireless sensor firmware so that the sensor will respond to polling from the base station. This is done using the Device Configuration Utility software. The A205 is also useful for connecting a computer directly to the CWS655, CWS220, or CWS900 for diagnosis, changing the base station radio address, uploading new firmware, and verifying sensor functionality. It is only necessary to purchase one A205—unless multiple users with multiple computers need to perform these tasks.

  2. Because the devices and the radios use the same frequency bands, there will be interference. Factors affecting the amount of interference include the distances between the communications radio and the CWS radios, and the distances between the CWS base and the sensors. Also, the amount of interference is affected by whether the communications radio is set up as a master.

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