Siemens SIMATIC S7-400H System Manual page 205

Depassivation of modules
Passivated modules are depassivated by the following events:
● When the fault-tolerant system starts up
● When the fault-tolerant system changes over to "redundant" mode
● After system modifications during operation
● If you call FC 451 "RED_DEPA" and at least one redundant channel or module is
The depassivation is executed in FB 450 "RED IN" after one of these events has occurred.
Completion of the depassivation of all modules is logged in the diagnostic buffer.
Note
When a redundant module is assigned a process image partition and the corresponding OB
is not available on the CPU, the complete passivation process may take approximately 1
minute.
S7-400H
System Manual, 03/2012, A5E00267695-11
passivated.
13.4 Connecting redundant I/O to the PROFIBUS DP interface
Using I/Os in S7–400H
205