Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual page 438

Function
Functions different Constant scan
(modified or
restricted) from
those of the process
mode
Interrupt function
Clock function
Writing data to the
CPU module
RAS function
28 FUNCTIONS
436
Description
• In the standby system, when the system is powered off, a
hardware failure has occurred, a tracking cable has a
failure, or the system is switched to the separate mode, a
continuation error may occur due to the excess of constant
scan time.
• The constant scan function is invalid for the standby system
in backup mode.
When the systems are switched during time measurement of
I28 to I31, I48, or I49, the time measurement interrupts and
the new control system starts the time measurement from 0.
Time The time of the standby system is synchronized with the time
synchronization of the control system in backup mode. The time setting using
the time setting function (SNTP client) is available only for the
control system.
System clock After system switching, SM420 (User timing clock No.0) to
SM424 (User timing clock No.4) remain off on the new control
system CPU module.
To use SM420 to SM424 on the new control system CPU
module, execute the DUTY instruction again.
Online change When the online change (ladder block) is performed on the
(ladder block) CPU module in one system in the backup mode, the change
is also reflected on the CPU module in the other system.
File batch online Data can be written only when the firmware version of the
change of FB files CPU modules of both systems supports writing of FB files and
and the global label the global label setting file online.
setting file
Scan monitoring • During system switching, scan time monitoring with the
function watchdog timer is interrupted. Thus, no error is detected
even if the scan time monitoring time has elapsed.
Therefore, a time taken for system switching does not need
to be considered in the scan time monitoring time setting.
• Scan time monitoring with the watchdog timer is interrupted
while the standby system is waiting for tracking data
reception. Thus, no error is detected even if the scan time
monitoring time has elapsed while the standby system is
waiting for tracking data reception. Therefore, a time taken
for tracking data reception does not need to be considered
in the scan time monitoring time setting.
Self-diagnostic The following items related to the redundant system are
function added to the contents that can be checked with the system
monitor.
• Tracking cable status
• Display of the main base units of systems A and B
• Module configuration on the base unit of the selected
system
• Event history of own system
• System to which a CPU module is belonged (control
system/standby system, system A/B) and operation mode
of the CPU module (backup mode/separate mode)
Error clear A continuation error occurred in own system can be cleared
by using the special relay (SM50) or the connected
engineering tool.
Clearing errors on Errors on the standby system CPU module can be cleared by
the standby system using the special relay (SM1679) of the control system CPU
CPU module from module.
the control system
CPU module
Reference
Page 488 Constant Scan



Page 489 Online
Change
Page 1008 Added and
Enhanced Functions

GX Works3 Operating
Manual
Page 133 Error Clear
Page 490 Clearing
errors on the standby
system CPU module
from the control system
CPU module