19 DATA LOGGING FUNCTION
19.6 Precautions
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Retention and clearance of data logging settings
The data logging settings registered in the CPU module are latched and thus survive across a power cycle (power off and on)
or reset of the CPU module in normal cases. In the following cases, however, the data logging status is cleared to the
unregistered state and therefore the setting data must be written again:
• The CPU module is turned off and on or reset without an SD memory card that contains the data logging setting file.
• The replaced SD memory card does not contain the data logging setting file and the CPU module is turned off and on or is
reset.
* 1
*1 If the data logging setting file contained in the replacement (new) SD memory card is different from that contained in the replaced (old)
SD memory card, the data logging setting file contained in the replacement SD memory card becomes registered.
Stopping/suspending data logging
After data logging is stopped or suspended from within the CPU Module Logging Configuration Tool or special relay, all the
data in the internal buffer is written into the target memory. If a small number of records or a small file size is specified as part
of the storage file switching condition, writes to the target memory may take a longer time.
Operation against the failure to register data logging setting files
When an attempt to register multiple data logging setting files at the same time is made and fails for some of them, the CPU
module runs data logging for the setting files that have been successfully registered.
Numbering of the storage files used during data logging
If one or more numbered storage files already exist in the specified file storage folder and a new file is written, the new file is
given a file name that uses a number incremented by one from the highest number among the existing files. If the file storage
folder has no storage files but one or more storage file container folders exist, the new file is stored under the folder with the
lowest number and it is given the same number as the folder. However, if there are 258 or more folders under the said
conditions, a new folder is created and the file is given the same number as the new folder.
Operation that occurs while collected data is stored in the target memory
If one of the following operations is performed while collected data is stored in the target memory, any unsaved data is cleared
and not reflected to the results:
• Turning power of the CPU module off and on
• Reset
If one of the following operations is performed, unsaved data continues to be stored in the target memory:
• Stopping the CPU module
• Stopping/suspending data logging from within the CPU Module Logging Configuration Tool
• Issuing the LOGTRGR instruction
Creating files and folders
Under the "LOGGING" folder that contains data logging setting files and data logging files, do not attempt to create files or
folders using a personal computer or other device. Doing so may result in deletion of files and folders.
Changing the clock data
Whatever changes, such as advancing or reverting the clock, are made to the clock data of the CPU module during data
logging, the CPU module performs data collection at the specified collection interval/timing, but the date/time column in the
output file reports the changed clock data.
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