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11/12/2019
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3.2 Real-time communication
Different performance levels are defined for PROFINET communication:
● In PROFINET data which are not time-critical, such as e.g. parameter data, configuration data and
connection information, are transferred via the standard data channel based on TCP / UDP and IP.
This means that the automation level can also be connected to other networks.
● For the transmission of time-critical process data PROFINET distinguishes between three real-
time classes, which differ in their performance:
–
Real-Time (RT Class1, RT)
- Use of standard components such as e.g. switches
- Comparable real-time characteristics to PROFIBUS
- Typical field of application is factory automation
–
Real-Time (RT Class2, RT)
- Synchronized or unsynchronized data transmission possible
- PROFINET-compliant switches must support synchronization
–
Isochronous Real-Time (RT Class 3, IRT)
- Synchronous data transmission
- Hardware support by Switch-ASIC
b- Typical field of application are drive controllers in
motion control applications
Figure 2: PROFINET communication mechanism
