Application planning
6.4 Redundancy scenarios
S7-1500R/H redundant system
System Manual, 01/2024, A5E41814787-AF
191
Sequence of events
1. The left interface module (slot 0) of the R1 device fails in PROFINET ring 1 and interrupts
PROFINET ring 1.
2. The redundant system will remain in the RUN-Redundant system state: The primary and
backup CPUs remain in the RUN-Redundant operating state. The roles of the primary and
backup CPUs do not change.
3. The redundant system selects an alternative connection over the backup CPU and the
PROFINET ring 2. This allows the redundant system to access the R1 device (via the right-
hand interface module at slot 1).
4. The redundancy of the system is restricted. The restriction has no effect on the process. If
another system component fails, the S7-1500R/H redundant system can fail as a result.
Diagnostics
System state, operating states and error displays after the failure of the interface module:
• Redundant system → RUN-Redundant system state
• Primary CPU/Backup CPU → RUN-Redundant operating state
– MAINT LED → yellow light: Interface module failed. The PROFINET ring 1 is open. No
backup AR.
Deviating diagnostics display
If you remove an interface module of an R1 device, the other interface module signals this
error with a red flashing ERROR LED. The LED error display has no effect on the process
because the second interface module of the R1 device takes over.
In the STEP 7 online diagnostics, the R1 device is shown only as "Maintenance demanded,
error in lower
-level component". The reason for this is the different diagnostics views of the
-CPU.
The IO device has only a local view and signals a missing module. The H
-CPU, on the other
-level view of the redundancy of the two interface modules. The
redundancy then results in the understated diagnostic information.
Therefore, when evaluating diagnostic information, pay attention not only to the LED error
display on the devices. For a complete evaluation of diagnostic information, you must also
look at the STEP 7 online diagnostics and evaluate the diagnostics buffer. You can find more
information in the Diagnostics
(https://support.industry.siemens.com/cs/ww/en/view/59192926) function manual.
Solution
Replace the defective interface module of the R1 device. You can find additional information
on the procedure in the section Replacing defective I/O devices/switches (Page 455).
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