Online Change; Constant Scan - Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual

37.12

Online Change

When the online change (ladder block) is performed on the CPU module in one system, the change is also reflected on the
CPU module in the other system.
Precautions
During an online change, avoid the following conditions.
• Changing the operating status of the CPU module from STOP (PAUSE) to RUN
• System switching
• Disconnection of the tracking cable
• Power-off or reset of the CPU module in the control system or standby system
When any of the above conditions is satisfied during an online change, a file mismatch is detected in the system consistency
check or the online change fails.
■Action for when an online change has failed
If an online change has failed, take the following actions.
1.
Get the CPU module ready for an online change and execute the online change with the same data as before the failure.
• If the online change succeeds, the action is completed.
• If the online change fails again, take the following actions.
2.
Verify the data in the control system CPU module with the programmable controller from the engineering tool, and check
whether the online change has been completed successfully.
• When the verification result is mismatched, the online change has not been completed successfully. Connect the
engineering tool to the control system CPU module, execute an online change only to the control system, and proceed to
step 3.
• When the verification result is matched but the program memory transfer window was not displayed at the online change,
the possible cause is that data transfer to the program memory has not been completed successfully. Batch-write files only
to the control system, and proceed to step 3.
• When the verification result is matched and the program memory transfer window is displayed (the online change is
completed successfully) during online change, proceed to step 3.
3.
Execute the memory copy from the control system to the standby system. When the memory copy has failed, power off
and on or reset the standby system CPU module and execute the memory copy again. ( Page 637 Memory Copy
from Control System to Standby System)
4.
Power off and on or reset the standby system CPU module.
37.13

Constant Scan

This section describes the precautions for setting the constant scan in the system using the SIL2 Process CPU.
Increase in scan time
In the standby system, when the CPU module is powered off, a hardware failure has occurred, or a tracking cable has a
failure, the scan time will increase in the control system.
When setting the constant scan, take one of the following measures.
• Set the setting time of the constant scan by adding the increase in the scan time when an error occurs. ( Page 926
Increase in the scan time due to tracking transfer)
• When a failure has occurred and a continuation error occurs due to the excess of constant scan time, clear the error. (
Page 671 Error clear)
For program executed in both systems
The constant scan function is invalid for the standby system.
37 FUNCTIONS
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37.12 Online Change