Campbell Scientific LoggerNet Datalogger Support Software - Manual (Page 440)

Section 11. Utilities Installed with LoggerNet Admin and LoggerNet Remote
11.3.5 Record Number Anomalies
Under certain circumstances it may appear there is a problem with the number
of records and their record numbers reflected by the Data Information table. It
is possible for the oldest record to have a record number higher than the newest
record. This is due to a combination of events.
Tables in dataloggers are configured as ring memory. Eventually, they will fill
and the oldest records will be overwritten with newer ones. The LoggerNet
data cache, too, is configured as ring memory, but sized to hold twice the
number of records that can be stored in the datalogger (default size). When the
datalogger compiles its program, it starts with record number 0; therefore, if
something causes the datalogger to recompile its program (such as sending a
program to the datalogger or using a keyboard display to alter the program
slightly) all of its tables will start with record number 0 again. Therefore, the
record numbers reflected in the Data Information table may appear to be
incorrect.
As an example, if the datalogger’s internal table size were 100 records,
LoggerNet’s cache would be sized at 200 records. If both had rung around and
LoggerNet’s cache now held record numbers 201–400 and someone re-sent the
same program to the datalogger, LoggerNet would not clear its data cache, but
would continue to store the new records. These record numbers, however,
would start at 0. After a short while as the new records were put into the data
cache and old ones overwritten, the earliest record in the data cache might be
251 while the newest record number might be 50. In the data file, however,
data would appear in correct sequence ordered by date/time stamps.
11.3.6 Communication Status
A box in the lower right corner of the Data Filer’s window provides an
indication of the Data Filer’s connection with the LoggerNet server. When the
Data Filer is in communication with the LoggerNet server, the box will appear
green and the IP address or computer name (e.g., LocalHost) will be displayed.
If communication with the server is lost (for instance, if LoggerNet is closed),
the box will appear red with the text “No Connection”. If communication is
lost but the Data Filer is attempting to reconnect, the box will appear blue with
the text “Attempting Connection”.
11.4 Data Export
The Data Export client provides a way to export the data collected by the
LoggerNet communications server to another computer program. In this role
the Data Export application acts as both a client and a server. It is a client to
the LoggerNet server and gets data from the LoggerNet data cache. It works as
a server to provide data to customer supplied client applications.
11.4.1 Functional Overview
The data to export is specified by selecting tables from each of the stations in
the datalogger network. When a data table is selected for export, every record
that the server collects from the datalogger for that table is sent out by Data
Export. If a table is selected but for some reason there is no data being
collected by the server, no data will be sent.
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