Siemens SIMATIC ET 200AL, System Manual

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Functions
5.4 Media redundancy (ring topologies)
PROFINET with STEP 7
182
Function Manual, 05/2021, A5E03444486-AL
Redundancy levels of IO devices with MRPD
The redundancy level of an IO device specifies how strongly the real-time communication is
influenced in the case of a power interruption between an IO device and its IO controller.
•
Full redundancy: No influence, because the IO controller and IO device are located in the
same ring.
• Partial redundancy:
– If the interruption takes place on a non-redundant part (line) between the IO device
and IO controller, real-time communication is influenced.
– If the interruption takes place on a redundant part (ring), real-time communication is
not influenced.
• No redundancy: No redundant path between the IO device and its IO controller,
communication is always influenced.
The figure below shows the redundancy levels of the IO devices for an example configuration
with MRPD. The three devices in the ring and the switch have the redundancy level "Full
redundancy". Device 4 has the redundancy level "Partial redundancy", because the connection
between the switch and the device is not redundant.
① IO controller in the ring
② IO device in the ring with redundancy level "Full redundancy"
③ Switch in the ring with redundancy level "Full redundancy"
④ IO device in the spur with the redundancy level "Partial redundancy"
Figure 5-40 Example configuration with MRPD