374
26 REDUNDANT FUNCTION
26.2 System Switching
26.2 System Switching
This function switches the systems between the control system and the standby system to continue operation of the
redundant system when a failure or an error occurs in the control system. For debugging and maintenance purpose, users
can switch the systems at any desired timing.
System switching method
The following two methods are available for system switching: automatic system switching (performed by a redundant
system) and manual system switching (performed by a user).
The following table lists the system switching types, causes, execution availability by operation mode of the redundant
system, and priority of when multiple causes are simultaneously generated.
: Operation possible, : Operation not possible
• When multiple system switching causes are simultaneously generated, the systems are switched according to the cause
with higher priority. The switching cause determined according to the priority is stored in the event history and SD1643
(System switching cause).
• A manual system switching request is executed for the CPU module of the control system.
The systems are not switched even when the CPU module is set to the STOP state. They are switched when
any of the above system switching causes is generated.
System switching type System switching cause Operation mode Priority
Backup mode Separate mode
Automatic system switching Power-off, reset, hardware failure of the CPU module High
Low
1
Stop error of the CPU module 2
System switching request from a network module 3
Manual system switching System switching request by the SP.CONTSW instruction 4
System switching request from the engineering tool 5
To Next Page
Loading...
