Failure and replacement of components during redundant operation   
11.1 Failure and replacement of central components 
  CPU 410-5H Process Automation/CPU 410 SMART 
172  System Manual, 10/2013, A5E32631667-AA 
 
How does the system react? 
The S7-400H is in redundant system mode and a 
communication module fails. 
•  Both CPUs report the event in the diagnostic 
buffer and via appropriate OBs. 
•  In communication via standard connections: 
Connection failed 
•  In communication via redundant connections: 
Communication is maintained without 
interruption over an alternate channel. 
If you want to use a communication module that is already being used by another system, 
you have to ensure that there are no parameter data saved in the module's integrated 
FLASH-EPROM before you swap it. 
Proceed as follows to replace a communication module for PROFIBUS or Industrial 
Ethernet: 
 
How does the system react? 
1  Remove the module. 
•  Both CPUs process the swapping 
interrupt OB 83 synchronized with each 
other. 
2  Insert the new module. 
•  Both CPUs process the swapping 
interrupt OB 83 synchronized with each 
other. 
•  The module is automatically configured by 
the appropriate CPU. 
3  Turn the module back on. 
•  The module resumes communication 
(system establishes communication 
connection automatically). 
 
Failure and replacement of a synchronization module or fiber-optic cable 
In this section, you will see three different error scenarios: 
●  Failure of a synchronization module or fiber-optic cable 
●  Successive failure of both synchronization modules or fiber-optic cables 
●  Simultaneous failure of both synchronization modules or fiber-optic cables 
The CPU indicates by means of LEDs and diagnostics whether the lower or upper redundant 
link has failed. After the defective parts (fiber-optic cable or synchronization module) have 
been replaced, LEDs IFM1F and IFM2F must go out.