System modifications during redundant operation   
10.6 Re-parameterization of a module 
  CPU 410-5H Process Automation/CPU 410 SMART 
164  System Manual, 10/2013, A5E32631667-AA 
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.  
 
One-sided I/O of previous 
master CPU 
One-sided I/O of new master 
CPU  
I/O modules 
are no longer addressed by the 
CPU.  
Output modules output the 
c
onfigured substitute or holding 
values. 
are given new parameter 
settings
1)
 and updated by the 
CPU. 
continue operation without 
interruption. 
1) Central modules are also reset first. Output modules briefly output 0 during this time (instead of the configured substitute 
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). 
Where the values for the monitoring times in the CPUs differ, the higher values always apply. 
 
Step 5: Transition to redundant system mode 
Starting situation 
The fault-tolerant system operates with the modified parameters 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".