Mitsubishi Electric MELSEC iQ-R Series User Manual page 304

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.
Events that are not recognized as a trigger condition
For trigger logging, the following events are not recognized as a trigger condition:
• A second trigger condition is met after the first trigger condition is met.
• The data condition specified as part of the trigger condition is met within the I49 interrupt program.
If a data condition is specified as part of the trigger condition, any trigger condition met during the execution of
the I49 interrupt program will not be recognized as a trigger condition. In this case, using I48 instead of I49
allows for avoiding the timing when the condition is not met.
Access to the SD memory card
If data logging is performed with a setting that the data collection interval is short or the number of records to be collected is
large, access (read/write) to an 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.
Access to the CPU module during data logging
When the multiple data logging settings are started at the same time (when the multiple data logging settings are registered
again at the same time), a time-out error may occur in communications or a dedicated instruction issued from a peripheral to
the CPU module. Take measures such as increasing the time-out time period of the peripheral, reducing some data logging
settings, and stopping the other functions.
Behavior at parameter change when functions consuming the internal buffer are active
If the internal buffer capacity setting is changed during the execution of the functions that consume the internal buffer,
attempting to start data logging results in an error, where the data logging fails to start.
Function that consumes
the internal buffer other
than data logging
Data logging
Internal buffer capacity setting changed
(by changing the parameters of
internal buffer capacity setting)
20 DATA LOGGING FUNCTION
302
20.16 Precautions to Take When Using the Data Logging Function
Function in execution
Function in execution
Data logging stopped
(by clicking [Stop] button)
An error occurs.
Data logging is not allowed to start.
Data logging attempted to start
(by clicking [Start] button)