Appendix C. Aggregating data
loggers
When you deploy a network of CRVW3 devices using radio telemetry, you have the option of
placing an aggregating data logger into that network. An aggregating data logger is a Campbell
Scientific data logger that connects to CRVW3 devices over a radio link and collects data from
them. That data, aggregated, is stored on the data logger for later retrieval by
LoggerNet
software or other means. For simple radio networks as well as for many other radio network
configurations, an aggregating data logger may not be necessary.
An aggregating data logger can also be configured as the base radio station, but that is not
required.
To be a part of the radio network, a radio that is compatible with the CRVW3 radio network must
be integrated to the data logger.
Reasons for using an aggregating data logger include the following:
l
A system other than
LoggerNet
(such as Modbus) is used to communicate with the
aggregating data logger, but not the CRVW3s
l
Sensors other than vibrating-wire sensors need to be measured as part of the system
l
Aggregation of the CRVW3 data is desired for backup or redundancy purposes
l
Only one point of contact for data within
LoggerNet
is desired (in this case, the aggregator
is the base station)
If you choose to use an aggregating data logger, you must include specific kinds of CRBasic
declarations and instructions in the data logger program that instruct it to contact the CRVW3s
and collect their data. This includes the use of the
GetDataRecord()
instruction.
C.1 Aggregator station configuration
If the aggregator station communicates with more than one remote station (whether CRVW3
stations, base station, or other repeaters), it should be configured with an omnidirectional
antenna. If it communicates with only one other station, a directional/Yagi antenna should be
used. If the aggregator station is also the base radio station, some other medium of
communications must be used between the data logger and
LoggerNet
(such as a serial cable,
CRVW3 3-Channel Vibrating-Wire Data Logger
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