192
19 DATA LOGGING FUNCTION
19.6 Precautions
Access to the SD memory card
If data logging is performed with a small setting of the data collection interval/timing or with a large number of records to be
collected, access (read/write) to the SD memory card occurs so frequently that a delay occurs in completing the access. To
avoid such a delay, use the following workarounds:
• Increase the data collection interval/timing.
• Reduce the number of data records to be collected.
• Lower the frequency of file switching.
Changing the operating status of the CPU module
The operating state of the CPU module should not be changed until the completion of the following operations and
registrations:
• Save of the data in the internal buffer by changing the state of the CPU module from RUN to STOP or instructing the CPU
Module Logging Configuration Tool to stop or suspend the CPU module
• Registering multiple data logging sessions' settings
*1
• Registering data logging settings with any unused folders remaining in the storage memory
*1
*1 Data logging settings are also registered when the CPU module is stopped and run.
• To shorten the time required to register multiple data logging sessions' settings, reduce the number of data
logging sessions.
• To shorten the time required to register data logging settings with any unused folders remaining in the
storage memory, delete the unused folders before registration.
File operation during execution of data logging
Describes file operation during execution of data logging.
About remote operation
When remote RUN is performed while the data logging function is in the following execution status, the remote RUN may fail.
In that case, wait for a while and retry remote RUN. If remote RUN still cannot be executed, check whether remote RUN is
acceptable and retry remote RUN.
RUN operation through switching operation or the RUN contact
During execution of data logging, when the status of the CPU module is switched from STOP to RUN with the RUN/STOP/
RESET switch, or when remote STOP to RUN operation of the RUN contact, it may take time to return to the RUN state.
Target file File operation Operation
Data logging setting file Write During execution of data logging, it is not possible to write or the delete data logging setting file being used.
Delete
Initialize During execution of data logging, it is not possible to initialize the memory storing the data logging setting file
being executed.
Folder delete Folders cannot be deleted from the $MELPRJ$ folder in which the data logging setting file is stored.
Data Logging File Write During execution of data logging, it is not possible to write or delete data, or delete folders corresponding to the
data logging file being used.
Delete
Folder delete
Initialize During execution of data logging, it is not possible to initialize the memory storing the data logging file being
executed.
Execution state of data logging function The situation to accept remote RUN
Data saving into memory card in progress No special relay (Data logging data saving into memory card in progress) is on.
Registration of the data logging setting from CPU Module
Logging Configuration Tool in progress
The special relay (data logging preparation) and the special relay (data logging start)
corresponding to the setting number of the data logging setting, which is being registered in the
way shown in the left column, are on.
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