System modifications during operation
17.5 Adding components in STEP 7
S7-400H
System Manual, 03/2012, A5E00267695-11
307
17.5.6 STEP 7, step 6: 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 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 previous
master CPU
One-sided I/O of new master
CPU
Switched I/O
Added I/O modules are not addressed by the CPU. are given new parameter settings and updated by the CPU.
The output modules temporarily output the configured
substitution values.
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
1)
and updated by the
CPU.
continue operation without
interruption.
Added DP stations are not addressed by the CPU. as for added I/O modules (see above)
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).
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