Data Logging at Runtime SECTION 11 Data Logging
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Unwanted groups can only be Deleted, they can not be cut or pasted.
11-3 Data Logging at Runtime
All data logging is performed on Items, which are stored in a Data Set. The
System can contain many Data Sets and each Data Set can contain many
Items. Each Data Set will have its own set of files when the System is run (see
the chapter 11, File Management). The amount of data that is stored in a
single Data Set file is determined by the specified period when the Data Set is
created.
11-3-1 File Management
11-3-1-1 Data Logging Directory
All data log files are stored in the directory "Data Logging" separate from the
CX-Supervisor files. This directory is created automatically when the project
runs for the first time. A sub-directory is used as a safeguard against the
accidental deletion of important files by the automatic purge mechanism and
to prevent the project directory from becoming cluttered with data files.
For example, if the CX-Supervisor project is in a directory called C:\CX-
Supervisor\Project then, when the project runs for the first time a new directory
called C:\CX-Supervisor\Project\Data Logging will be created to hold the data
log files.
11-3-1-2 Data Logging Files
Each Data Set has its own set of files. The following conventions have been
adopted in order to identify the various files and add time and date information.
Data Log files are assigned the file extension .dlv "Data Log Values" and the
format of the filename is:
<Data Set Name><Time Stamp>.dlv
The Time Stamp is in the format: [YYYY MM DD HH]"
where:
YYYY = Year in the form 1999
MM = Month in the form 01 (January)
DD = Day of the month in the form 01 - 31
HH = Hours in the form 00 -23
Daylight time saving is automatic.
For example:
Data Set 1 Miller[1999012015].dlv
A new log file is automatically created when the preceding file has expired the
timestamp. The timestamp is also used to distinguish between files in the
same Data Set. The time period for each file is determined by the options
selected when the Data Set was created. The minimum time period for a Data
Set file is one hour commencing on the hour.
Note: Do not rename any log files while they are in the Data Logging directory or the
File Management System will not work correctly. The File Management
System relies on the strict format of the Data Log files to determine which file
to open as Live and which file(s) to delete during purging and also for
performing 'previous/next' file searches in the Data Log Viewer.
Note: Additional files should never be copied into the Data Logging directory as the
automatic purging mechanism may delete all the log files.
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