HEIDENHAIN PROFINET - Manual (Page 48)

PROFINET IO data description
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4.12 Real time communication
PROFINET IO uses three different communication channels to ex-
change data with programmable controllers and other devices.
The non real time channel based on for example TCP (UDP)/IP is
used for parameterization, configuration and acyclic read/write
operations.
The RT or Real Time channel is used for process data transfer and
alarms.
Real-time data are treated with a higher priority than data sent
over the open channel. RT communications overrides the open
channel to handle the data exchange with programmable Control-
lers.
The third channel, Isochronous Real Time (IRT) is the high perfor-
mance, high speed channel used for demanding motion Control
applications. IRT data are treated with a higher priority than RT da-
ta sent over the RT channel.
Figure 28 Real time Communication