Siemens SIMATIC ET 200AL, System Manual

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Functions
5.5 Real-time communication
PROFINET with STEP 7
Function Manual, 05/2021, A5E03444486-AL
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Setting up PROFINET with IRT
Keep in mind the following rules for setting up and operating a PROFINET IO system in
IRT mode. These rules will ensure best possible operation of your PROFINET IO system.
•
When using IRT, you must configure the topology. This will enable exact calculation of the
update time, bandwidth, and other parameters.
• If you would like to use multiple sync domains, configure a sync boundary for the port
which is currently connected to the PROFINET device of another sync domain.
• In a sync domain, you can only configure one sync master at a time.
• A PROFINET IO system may only be part of a single sync domain.
• If you configure PROFINET devices in a sync domain and want to synchronize with IRT, the
PROFINET devices concerned must support IRT communication.
• If possible, use the same PROFINET device as the PROFINET IO controller and sync master.
• If only some of the PROFINET devices in a PROFINET IO system are synchronized, please
keep in mind the following: Assign PROFINET devices that are not participating in the IRT
communication to the RT class "RT" and the synchronization role "unsynchronized" in the
sync domain.