Configuring Hardware and Communication Connections STEP 7.pdf

Configuring IRT Communication
Limiting Network Load
To limit the load on the network caused by extremely short update times, update
groups are configured for IRT data. If a only a few devices require the shortest
update time, they are assigned to the first update group. Each additional update
group has an update time that is "n times" the previous update group (the factor "n"
can be configured). This means that their data are updated less often, thus
reducing the network load.
In STEP 7 V5.4 there is only one update group.
IRT Runs in Parallel to Realtime and TCP/IP Communication
In addition to IRT communication, for which a specified bandwidth within the
update time is reserved, RT communication and TCP/IP communication are also
allowed during the update time "n".
With RT communication (realtime communication), the cyclical data is transmitted
between the IO controller and the IO device, but without the "best-possible
synchronization".
Unsynchronized IO devices exchange their data automatically using RT
communication.
Since TCP/IP communication is also possible, other non-realtime data or
configuration data or diagnostic data can also be transported.
Configuring Hardware and Communication Connections with STEP 7
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