Campbell Scientific CWS220 Wireless Sensor Network (CWB100, CWS220, and CWS900 - Page 49
Replacing a Sensor in the Network, 2 Stopping or Loading a New Datalogger Program
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Wireless Sensor Network Distilled water or alcohol works well for most dust/dirt. Salt deposits dissolve better in a weak acid solution (~0.1 molar). Sensors connected to the CWS900 may require regular maintenance and recalibration. See the documentation for the sensor of interest for recommended maintenance and recalibration details. 7.1 Replacing a Sensor in the Network If a sensor in the network needs to be replaced, the CWB100 treats the replacement sensor as a new sensor because it has a different radio address than the original sensor. The data transmitted by the replacement sensor will have the same field names as the original sensor, but with a ~ appended to each name by the datalogger support software to make it unique. The original sensor will still appear in the final storage data file with NAN's instead of values because the sensor is no longer working. Data from the replacement sensor will be saved to a different position in the final storage data file with field names that include the ~ character. If a sensor has not responded to six polls by the CWB100 and it has been more than two hours since the last communication, the CWB100 will stop polling that sensor. The only way to fully remove a sensor from the network and replace it with another is to force the datalogger to read the sensor names from the CWB100 after the replacement sensor is configured and installed. Changing the size of the array or the scan interval in the datalogger program, for example, will force that reading when the program is compiled. In that case the ~ character will not be appended to the new sensor's field names. If a configuration file or string is used in the CWB100( ) instruction, then the replacement sensor is accommodated by using a new file or string that has the old radio address replaced with the new radio address. The configuration file is only read by the datalogger one time at compile, so a change to the configuration file must be accompanied by a restart of the datalogger program for the new file to be used. 7.2 Stopping or Loading a New Datalogger Program If the datalogger program is stopped or a new program loaded, the CWB100 base station will still retain its information for the discovered sensors in the network. The sensors will not have to initiate auto-discovery. If the sensors are not polled by the base at least once in 13 hours, the sensors will initiate the auto-discovery process just as if the Setup button had been pressed to start auto-discovery. 41