Campbell Scientific Wireless Sensor Network (CWB100, CWS220, and CWS900) - Manual (Page 34)

Wireless Sensor Network
Determining Size of the Array
In this example the WSN includes a CWS655 and a CWS900 configured to
measure a 109 temperature probe. Section 1.3 shows that the CWS655
transmits 8 values and Section 1.4 shows that the CWS900 transmits 4 values
when configured to measure a 109 probe. Thus the array needs to be sized to
accept at least 12 values:
Public WSN(12)
Note that since the array is sized to fit the number of incoming values exactly,
no additional wireless sensors may be added to this network without first
modifying the datalogger program.
Determining the Scan Rate
The scan in which the CWB100() instruction resides must be long enough to
allow for 15 seconds per sensor per hop. If the CWB100RSSI() instruction is
used also, an additional 15 seconds/sensor/hop must be included. In this
example, each sensor needs only one hop to transmit data to the base station.
At 15 seconds per hop, the minimum scan rate is 30 seconds. For this program
a more conservative scan rate of 60 seconds will be used:
Scan (60,Sec,0,0)
.
.
.
NextScan
The 60 second scan rate in this example provides a relatively fast
check of system components, but will drain the sensor’s batteries
within a few months. In practice, a more typical scan rate is in
the range of 5 to 15 minutes. See Appendix C for details on
battery life. NOTE
Inserting the CWB100() Instruction
For the CWB100() instruction, specify the odd numbered control port where
the CWB100 radio will attach to the datalogger (C1), the destination array
where CWS measurements will be stored, and the name of the configuration
string (in quotes “ “):
CWB100(1, WSN(),”CPU:CWSConfig.txt”)
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