28 FUNCTIONS
28.15 Data Logging Function
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Data logging states at system switching
The following table lists the data logging states that change at system switching.
■When the control system is switched to the standby system
■When the standby system is switched to the control system
Before using the data logging function, check if the SD memory card inserted in the standby system CPU
module has sufficient free space with a program. When the SD memory card inserted in the standby system
CPU module does not have sufficient free space and the systems are switched, an error occurs at the data
collection in the new control system and the data collection is finished.
To prevent occurrence of an error, use a program that turns on the annunciator when the free space of the SD
memory card of the standby system is smaller than the value of the criteria, such as the one shown below.
• For the above program, set "Both Systems Executions" for "Both Systems Program Executions Setting" of
the CPU parameter. ( Page 479 Program Execution in Both Systems)
• Set the value of the criteria in D0 in increments of K of the double word [unsigned].
LED status
The following table shows the LED status in the data logging states of the standby system.
Data collection conditions
When time specification has been set as a data collection condition and the systems are switched during data logging, time
measurement starts from 0 in the new control system, and data is not collected at the specified interval.
Trigger logging
If the systems are switched while trigger logging is being executed, logging data collected in the old control system is
discarded.
Before system switching (old control system) After system switching (new standby system)
Waiting Start Not Collected Standby system start waiting
Pause Standby system pause
Waiting to establish collection conditions Not collected Standby system no collection
Collecting
Waiting trigger Collecting before trigger
After Trigger Collecting
Before system switching (old standby system) After system switching (new control system)
Standby system start waiting Waiting Start Not Collected
Standby system pause Pause
Standby system no collection Waiting to establish collection conditions Not collected
State of the data logging function LED status
Execution in
progress
All of the registered data logging sessions are in the "Standby System Start Waiting", "Standby
System Pause", or "Standby System No Collection" state.
• CARD READY LED: On
• CARD ACCESS LED: Off
• FUNCTION LED: On
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