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26 BASIC CONCEPT
26.7 Determination of Control System/Standby System
When starting up the previous control system as the control
system
In a redundant system, the system A is always specified as the control system when both systems are started up
simultaneously.
Even though both systems are temporarily powered off due to a power failure or other causes while the system B is operating
as the control system, the system A is started up as the control system when both systems are powered on again.
To start up the system B that was the previous control system as the control system again, create a program that uses
SM1636 (Previous control system identification flag).
For a system where a network module has been mounted, execute the SP.CONTSW instruction after a network module on
the other system is started up.
Program example
Executing a system switching instruction when the CPU module in the system A is set to the RUN state for the first time
switches the system B to the control system.
Turn on SM1646 (System switching by a user) in advance.
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