● Recovery from System–wide Power Off
Power off and then power on, not just the FCN-500 or FCN-RTU but the entire
system. Check the operation after power is restored.
● Operation and Recovery after Failure of One of Two Duplex CPUs (FCN-
500 only)
To sim ulate failure of one of two duplexed CPUs, press the RESET button of the
corresponding CPU.
When the control CPU is made to fail, control right is transferred to the standby CPU
and control continues. However, control switchover causes momentary interruption
of the communication over the control network, which is restored shortly after.
When the standby CPU is made to fail, control continues with the control CPU
running like a single CPU.
Verify that control switchover and momentary interruption of the control network do
not cause control problems.
To recover from single CPU state to duplexed CPU state requires execution of APC
(All Program Copy).
If automatic APC is enabled, APC is automatically executed after control switchover.
If automatic APC is disabled, execute APC manually using Resource Configurator.
Moreover, control continues during APC execution, but the control cycle is
lengthened by 1 to 2 seconds for one cycle.
Verify that there is no problem in control operation during APC execution and after
duplexed configuration is restored by APC execution.
SEE ALSO
For details on the operation specification and precautions of Duplex FCN-500 CPU modules, see:
Section B1.3.3, “Precautions on the Creation of Control Applications” of IM “STARDOM FCN/FCJ
Guide.”
Chapter C2 , “Duplex CPU Module (FCN)” of IM “STARDOM FCN/FCJ Guide.”
Section 7.2, “Operation Using Duplex FCN CPU Modules” of TI “FCN-500 Technical Guide”
The control and standby CPUs synchronize their timing while accessing process I/O.
When I/O is put in disconnected state for debug purposes, process I/O is
inaccessible, consequently the control CPU and standby CPU cannot be
synchronized. Therefore, when disconnecting I/O, switch the CPU to single mode.
Testing control switchover with the control CPU and standby CPU in non-
synchronized state is not only meaningless but may even cause abrupt changes in
control output.
To avoid this, cancel I/O disconnection before testing control switch over.
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