Siemens SIMATIC PROFINET Function Manual page 170

Functions
5.5 Real-time communication
Topological overlap of IO systems in multi-controller applications
In a configuration with multiple IO controllers, shared paths are subject to the combined
network loads of all connected PROFINET IO systems.
To avoid high communication loads in multi-controller applications, observe the following
recommendations:
● Avoid paths that are shared by multiple IO systems.
The figure below shows a configuration with two PROFINET IO systems that use the
same paths.
①
Figure 5-52
In the figure below, the two PROFINET IO systems do not use shared paths.
Figure 5-53
● If separation is not possible: Increase the update time for the affected IO devices.
Installation guidelines of the PROFIBUS user organization
The installation guidelines can be found on the Internet
(http://www.profibus.com/nc/download/installation-guide/downloads/profinet-installation-
guide/display/).
170
Shared path
Multi-controller application with shared path
Multi-controller application with separate paths
PROFINET with STEP 7 V14
Function Manual, 09/2016, A5E03444486-AG