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CWS900A 922 MHz Configurable Wireless Sensor Interface for Australia
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Repair Yes
Calibration Yes
Free Support Yes


The CWS900A allows a sensor with a special connector to be used in a wireless sensor network; the special connector is available as an option for a large variety of sensors. (See the Compatibility information on the web page.)

The CWS900A contains an internal 922 MHz spread-spectrum radio that transmits data to the CWB100A Wireless Base Station or to another wireless sensor. The frequency of the internal radio is commonly used in the Australia and New Zealand.

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Benefits and Features

  • Allows a wide variety of sensors to be used in a wireless network
  • 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

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 CWS900A has a sealed connector for attaching one rain gage, wind sensor, temperature/RH probe, or another low-power sensor. It measures analog voltages, low-level ac, pulse counts, and can supply an excitation voltage for powering some sensors or making bridge measurements. The type of measurement that the sensor performs is configured using Wireless Sensor Planner, Network Planner, or DevConfig software. The CWS900A interfaces with the PC for configuration via the A205 CWS Sensor to PC Interface.

The CWS900A can route its transmissions through up to three other wireless sensors. A data logger is connected to the CWB100A base station for processing and storing the CWS900A's data.

This interface is battery powered using either alkaline batteries or a rechargeable battery and a solar cell.

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 data logger 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 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 and depending on attached sensor)
Analog Channels
  • SE1, SE2, SE3 (single-ended)
  • DF (differential)
Analog Input Range -1 to +2.5 Vdc
Resolution 0.3 μV
Excitation Voltage 2.5 V, 3.3 V, 5.0 V (20 mA maximum)
Excitation Voltage Accuracy ±2% (-35° to +70°C)
Low-Level AC Input 20 mV minimum (10 kHz maximum frequency)
Temperature Accuracy ±0.2ºC
Analog Measurement Accuracy
  • ±(0.02% of reading + 2 µV) (0° to 50°C)
  • ±(0.05% of reading + 2 µV) (-35° to +70°C)
Bridge Measurement Accuracy (+2.5 V excitation only)
  • ±(0.03% of reading + 3 µV) (0° to 50°C)
  • ±(0.07% of reading + 3 µV) (-35° to +70°C) Not including sensor and measurement noise,and external bridge resistor errors.
Dimensions 15 x 6 x 4.5 cm (5.9 x 2.4 x 1.77 in.)
Weight 184 g (6.5 oz)

Switch Closure

Maximum Count Rate 100 Hz
Minimum Open Time 5 ms
Minimum Closed Time 5 ms
Maximum Bounce Time 4 ms
Maximum Number of Counts Records 1,000,000 counts before it rolls over.

Internal 25 mW FHSS Radio

Frequency 920 to 928 MHz
Where Used Australia and New Zealand
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


Note: The following shows notable compatibility information. It is not a comprehensive list of all compatible or incompatible products.

Data Loggers

Product Compatible Note
CR1000 (retired)
CR200X (retired)
CR206X (retired)
CR211X (retired)
CR216X (retired)
CR295X (retired)
CR9000X (retired)


Product Compatible Note
03002-L With -CWS option
034B-L With -CWS option
05103-45-L (retired) With -CWS option
05103-L With -CWS option
05106-L (retired) With -CWS option
05305-L With -CWS option
109 With -CWS option
109SS-L With -CWS option
110PV-L With -CWS option
CMP11-L With -CWS option
CMP6-L With -CWS option
CS215-L (retired)
CS300-L (retired) With -CWS option
CS511-L With -CWS option
CSAT3 (retired)
HC2S3-L (retired) With -CWS option
HFP01-L With -CWS option
HMP60-L With -CWS option
LI190SB-L (retired) With -CWS option
LI200S-L (retired) With -CWS option
LI200X-L (retired)
LWS With -CWS option
OBS-3+ (retired)
OBS300 (retired)
OBS500 (retired)
TB4-L With -CWS option
TB4MM-L With -CWS option
TE525-L With -CWS option
TE525MM-L With -CWS option
TE525WS-L With -CWS option
WINDSONIC-L (retired)

Additional Compatibility Information

Data Logger Considerations

Compatible Data Logger Operating Systems
  • CR800-Series: CR800.Std.21 and higher
  • CR1000: CR1000.Std.21 and higher
  • CR3000: CR3000.Std.21 and higher
  • CR6: Version 4.0 and higher


One sensor attaches to the CWS900A. Sensors with the -CWS option will include a connector that mates with the CWS900A. Alternatively, a sensor can connect with the CWS900A via the A150 Desiccant Case.

A150 Desiccated Case

The A150 Desiccated Case has a -CWS cable termination option. It allows our CS450 and CS455 pressure transducers or other sensors that have a vented cable to be connected to the CWS900A. Sensors that measure analog voltages, frequency, and pulse can also use the A150 to connect with the CWS900A.


CWS900 Firmware v.5 (448 KB) 03-30-2016

Latest firmware for the CWS900.  

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 CWS900A: 4

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  1. To incorporate a sensor that is compatible with wireless sensor interfaces into a wireless network, a CWS900-series wireless sensor interface is needed, as well as an A205 CWS-to-PC interface to configure it. 

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