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19 DATA LOGGING FUNCTION
19.5 Details of Specifications
Storage file
The CPU module creates a subfolder ("storage file container folder") under the file storage folder and writes storage files to
that storage file container folder. One storage file container folder can contain up to 256 storage files. When the files contained
in the current storage file container folder reach the maximum number, the CPU module creates a new storage file container
folder at the time of next storage file switching and begins writing storage files to that new folder. The number of files that can
be contained in one file storage folder is configurable within the range of 1 to 65535.
The base folder name of a storage file container folder is an eight-digit (hexadecimal) number. This number
matches the lowest of the serial numbers of the files contained in the directory. Date and time stamps can be
appended to the folder name.
Action to take when the maximum number of storage files is exceeded
Either "Overwrite" or "Stop"
*1
can be selected as the action to take when the maximum number of storage files is exceeded.
*1 This settings is not configurable for trigger logging.
■When "Overwrite" is selected
When the storage file switching condition is met after the specified maximum number of storage files is exceeded, the CPU
module deletes the file with the lowest serial number and creates a new file that has a serial number incremented by one from
the highest serial number, allowing data logging to continue. In addition, if deleting the file with the lowest serial number
results in an empty folder, the CPU module deletes that folder as well.
■When "Stop" is selected
As described in the following table, the action differs depending on when the specified maximum number of storage files is
exceeded.
*1 When an attempt is made to register the data logging settings again, the CPU module enters into the data logging completed state. The
special relay (data logging completed) turns on to indicate that data logging is completed.
Occurrence timing Occurrence condition Operation
When data logging is
started
There exist more storage files than the
specified maximum number when data
logging is started.
• If an attempt is made to register the data logging settings from within the CPU
Module Logging Configuration Tool, an error is generated, resulting in failure to run
data logging.
• If an attempt is made to register
*1
the data logging settings from outside the CPU
Module Logging Configuration Tool, the special relay (data logging error) turns on
and the special register (data logging error cause) stores the cause of the error,
resulting in failure to run data logging.
While data logging is
running
The specified maximum number of storage
files is reached due to file switching upon
the satisfaction of the storage file switching
condition.
Data logging stops and enters into the completion state. The special relay (data
logging completed) turns on to indicate that data logging is completed.
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