26 BASIC CONCEPT
26.6 Scan Configuration
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26
26.6 Scan Configuration
This section describes scan configurations of the CPU modules in a redundant system.
In a redundant system, tracking is performed during the END processing. ( Page 454 Tracking Transfer)
For details on other than tracking transfer, refer to Chapter 1. ( Page 38 Scan Configuration)
The following figure shows scan configurations of when both systems are started up simultaneously in the backup mode.
Both systems perform different processing depending on the set operation mode.
: Performed, : Not performed
*1 Only the input refresh is performed. Whether or not to perform the output refresh depends on "Standby System Output Setting" of "CPU
Parameter". ( Page 485 Redundant System Operation Setting)
*2 The program operation is not performed with the default setting. Programs are executed according to "Both Systems Program
Executions Setting" in "Program Setting" of "CPU Parameter". ( Page 479 Program Execution in Both Systems)
*3 This processing will not be performed when the operation mode is changed from the backup mode to the separate mode.
Processing Backup mode Separate mode
Control system Standby system Control system Standby system
Initial processing/initial processing (when
switched to RUN)
*3
*3
I/O refresh
*1
Program operation
*2
Tracking transfer
END processing
Program operation
Tracking transfer
CPU module is
switched to RUN
Initial processing
(when switched to RUN)
I/O refresh
Scan
time
END processing
Tracking transfer
CPU module is
switched to RUN
Initial processing
(when switched to RUN)
I/O refresh
Scan
time
END processing
Sending tracking data
Reception completion of
tracking data
<Control system> <Standby system>
Operation of the program
executed in both systems
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