System modifications during redundant operation   
10.4 Removal of components 
  CPU 410-5H Process Automation/CPU 410 SMART 
152  System Manual, 10/2013, A5E32631667-AA 
 
One-sided I/O of 
previous master CPU 
One-sided I/O of new 
master CPU  
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 
are given new parameter 
settings
2)
 and updated by 
the CPU. 
continue operation 
without interruption. 
DP stations to be 
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 110). 
 
Step 6: Transition to redundant system state 
Starting situation 
The fault-tolerant system is operating with the new hardware configuration in single mode. 
1.  In SIMATIC Manager, select a CPU of the fault-tolerant system, then select "PLC > 
Operating Mode" from the menu. 
2.  From the "Operating Mode" dialog box, select the reserve CPU, then click "Warm 
Restart".