Siemens S7-300 - Further Information on Operation with PROFINET IO; Effects of Multicast Communication on RT Communication

CP as PROFINET IO controller
6.4 Further information on operation with PROFINET IO
Configuring and commissioning S7 CPs for Industrial Ethernet
120 Configuration Manual, 09/2013, C79000-G8976-C182-13
6.4
Further information on operation with PROFINET IO
6.4.1
Effects of multicast communication on RT communication
PROFINET IO RT communication at the same time as broadcast (BC) or multicast (MC)
Note
Note the effects when PROFINET IO communication (RT frames)
are used at the same time
as broadcast (BC) or multicast (MC) in an Industrial Ethernet subnet. In this case, RT frames
may be delayed by long BC frames or MC frames.
These frames can, for example, be generated by the program blocks AG_SEND or
AG_RECV.
Wit
h certain constellations, this can lead to a PROFINET RT communication abort. The
factors that influence this are the switch configurations ("switch depth"), the update time and
the MC/BC frame lengths.
See also
You will find more detailed information on the influencing factors and possible solutions on
the Internet under the following entry ID:
29104898 (http://support.automation.siemens.com/WW/view/en/29104898)