Siemens SIMATIC S7-1500 System Manual page 49

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Figure 4-17 Failure of the PROFINET cable between the CPUs
If the cyclic program exceeds the cycle monitoring time, the time error OB (OB 80) may be
started. Redundancy is lost if the time error OB (OB 80) is not present or the double cycle
monitoring time was exceeded with OB 80. You can find additional information on the
response of the S7-1500R/H redundant system when cycle time is exceeded in the section
Events and OBs.
NOTE
If failure of the PROFINET cable that directly connects the two CPUs of the redundant
S7-1500R system is unlikely, you can use PROFINET devices without H‑Sync forwarding in
the PROFINET ring of the redundant S7‑1500R system.
Example: Both CPUs of the redundant S7-1500R/H system are located next to each other
in the control cabinet. In this case, it is unlikely that the PROFINET cable will fail.
System redundancy S2
System redundancy S2 is the connection of an IO device via an interface module that
supports two ARs to the IO controllers in the redundant system.
IO devices with system redundancy S2 enable uninterrupted process data exchange with the
S7-1500R/H redundant system in the event of:
• a CPU fails
• Interruption of the PROFINET ring
• Interruption of the line topology (for S7-1500H as of FW version V3.0)
An IO device with system redundancy S2 supports system redundancy ARs.
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD
The redundant S7-1500R system is in the RUN-Redundant system state.
The PROFINET cable which directly connects the two CPUs fails.
The PROFINET ring is interrupted.
The PROFINET ring is being reconfigured.
PROFINET devices without H-Sync forwarding do not forward any H-Sync frames during the
reconfiguration time of the PROFINET ring.
The cycle time increases by the reconfiguration time of the PROFINET ring.
System overview
4.3 S7-1500 R/H-CPUs
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