Failure and replacement of components during operation
16.3 Failure and replacement of components of the distributed I/Os
S7-400H
278 System Manual, 03/2012, A5E00267695-11
16.3.3 Failure and replacement of a PROFIBUS DP slave
Starting situation
Failure How does the system react?
The S7-400H is in redundant system mode and a
DP slave fails.
Both CPUs report the event in the diagnostic
buffer and via the appropriate OB.
Procedure
Proceed as follows to replace a DP slave:
Step What has to be done? How does the system react?
1 Turn off the supply for the DP slave. –
2 Remove the bus connector. –
3 Replace the DP slave. –
4 Plug the bus connector back in and turn the
power supply back on.
The CPUs process the rack failure OB
86 synchronized with each other
(outgoing event)
The associated DP master can address
the DP slave.
16.3.4 Failure and replacement of PROFIBUS DP cables
Starting situation
Failure How does the system react?
The S7-400H is in redundant system mode and
the PROFIBUS DP cable is defective.
With single-channel one-sided I/O:
Rack failure OB (OB 86) is started (incoming
event). The DP master can no longer process
connected DP slaves
(station failure).
With switched I/O:
I/O redundancy error OB (OB 70) is started
(incoming event). DP slaves are addressed
via the DP master of the partner.
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