System modifications during redundant operation
10.4 Removal of components
CPU 410-5H Process Automation
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System Manual, 09/2014, A5E31622160-AB
10.4.5
Step 5: Switch to CPU with modified configuration
Starting situation
The modified hardware configuration is downloaded to the reserve CPU.
Procedure
1.
In SIMATIC Manager, select a CPU of the fault-tolerant system, then choose "PLC >
Operating Mode" from the menu.
2.
In the "Operating Mode" dialog box, click the "Switch to..." button.
3.
In the "Switch" dialog box, select the "with altered configuration" option and click the
"Switch" button.
4.
Acknowledge the prompt for confirmation with "OK".
Result
The reserve CPU links up, is updated (see section Link-up and update (Page 121)) and
becomes the master. The previous master CPU switches to STOP mode, the fault-tolerant
system operates with the new hardware configuration in single mode.
Reaction of the I/O
Type of I/O
One-sided I/O of previ-
ous master CPU
One-sided I/O of new
master CPU
Switched I/O
I/O modules to be
removed
1)
are no longer addressed by the CPU.
Driver blocks are no longer present.
I/O modules still
present
are no longer addressed
by the CPU.
Output modules output
the configured substitute
or holding values.
are given new parameter
settings
2)
and updated by
the CPU.
continue operation with-
out interruption.
DP stations to be
removed
as for I/O modules to be removed (see above)
1) No longer included in the hardware configuration, but still plugged in
2) Central modules are first reset. Output modules briefly output 0 during this time (instead of the
configured substitute or hold values).
Reaction to monitoring timeout
The update is canceled and no change of master takes place if one of the monitored times
exceeds the configured maximum. The fault-tolerant system remains in single mode with the
previous master CPU and, assuming certain conditions are met, attempts the master
changeover later. For additional information, refer to section Time monitoring (Page 123).