Precautions When The Data Logging Function Is Used - Mitsubishi Electric MELSEC iQ-R Series User Manual

Precautions when the data logging function is used

If the systems are switched while data logging fails (processing overflow) due to frequent and continuous data logging
collection, data logging continues frequently and continuously in the new control system, and thus the scan time of the new
control system increases considerably. Therefore, a WDT error may occur in the new control system and both systems may
stop. To avoid the above problem, check the following at system start-up.
• After the redundant system has started, the control system does not fail in data logging collection (processing overflow).
• After system switching, the new control system does not fail in data logging collection (processing overflow) and the CPU
module operates without errors.
*1 Whether a processing overflow has occurred or not can be checked in the special register (Number of processing overflow occurrences)
corresponding to the data logging No. ( Page 668 List of Special Register Areas)
To prevent both systems from stopping, review the following settings.
• Collection interval and data to be collected in the data logging setting ( CPU Module Logging Configuration Tool Version
1 Operating Manual (MELSEC iQ-R Series))
• "Scan Time Monitoring Time (WDT) Setting" of the CPU parameter ( Page 200 Scan time monitoring time setting)
When using the data logging function, note that the number of writings to the SD memory card is limited.
*1
5 PROCEDURE FOR STARTING UP A REDUNDANT SYSTEM
*1
5
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5.1 Overview