Step 4: Switching To Cpu With Modified Configuration - Siemens SIMATIC S7-400H System Manual

17.9.5

Step 4: Switching 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 >
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
4. Acknowledge the prompt for confirmation with "OK".
Result
The reserve CPU links up, is updated and becomes the master. The previous master CPU
switches to STOP mode, the fault-tolerant system continues operating in single mode.
Reaction of the I/O
Type of I/O
I/O modules
1) 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 155).
Where the values for the monitoring times in the CPUs differ, the higher values always apply.
S7-400H
System Manual, 03/2012, A5E00267695-11
Operating Mode" from the menu.
"Switch" button.
One-sided I/O of previous
master CPU
are no longer addressed by the
CPU.
Output modules output the
configured substitute or holding
values.
System modifications during operation
17.9 Re-parameterization of a module
One-sided I/O of new master
CPU
are given new parameter
settings and updated by the
1)
CPU.
Switched I/O
continue operation without
interruption.
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