Campbell Scientific Wireless Sensor Network (CWB100, CWS220, and CWS900) - Manual (Page 9)

Wireless Sensor Network
1. Understanding a Wireless Sensor Network
1.1 General Description
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 even possible. Local fire codes may preclude the
use of certain types of sensor cable inside 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. Each of these instances can be resolved with a
Campbell Scientific Wireless Sensor Network (WSN). A WSN provides a
reliable, low maintenance, low power method for making measurements in
applications where cabled sensors are impractical or otherwise undesirable.
What is it?
A Campbell WSN consists of a CWB100 Wireless Base Station and one or
more Campbell Wireless Sensors (CWS). The base station communicates with
a Campbell Scientific CR800-series, CR1000, or CR3000 datalogger, which
serves as the gateway to the network. Although compatible dataloggers use the
PakBus© communication protocol, PakBus© is not used for the datalogger to
base station communication, nor for the base station to sensor communication.
In other words, the CWB100 and wireless sensors are not PakBus© devices.
The base station communicates with all of the wireless sensors in the network.
Any sensor can serve as an RF repeater to communicate with other wireless
sensors. A sensor can route its transmissions through up to three other sensors
on the way back to the base station.
Wireless sensors include the CWS220 Wireless Infrared Radiometer, the
CWS655 Wireless Water Content Reflectometer, and the CWS900 Wireless
Sensor Interface. Additional sensor types can be integrated into the network by
connecting them to the CWS900 Wireless Sensor Interface.
How does it work?
The CWB100 Wireless Base Station and one or more wireless sensors are first
configured using an A205 CWS to PC Interface and Campbell Scientific’s
Wireless Sensor Planner, Network Planner or Device Configuration Utility
software.
The datalogger is programmed with the CRBasic editor to interface with the
CWB100 and determine a polling interval. After the polling interval has been
received, the base station uses that information to poll the sensors prior to
being polled by the datalogger. Power is applied to the sensors and a Setup
button pressed to cause them to establish a route to the base station. The base
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