Siemens SIMATIC ET 200AL, System Manual

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Functions
5.5 Real-time communication
PROFINET with STEP 7
192
Function Manual, 05/2021, A5E03444486-AL
5.5 Real-time communication
5.5.1 Introduction
Properties
PROFINET IO is a scalable real-time communication system based on the Layer 2 protocol for
Fast Ethernet. With the RT transmission method, two real-time-support performance levels
are available for time-critical process data and IRT for high-accuracy and also isochronous
processes .
Figure 5-49 Real-time communication performance
Real-time communication and IT communication
Industrial communication, especially in the factory automation and process automation,
requires a punctual and deterministic data transmission. This is why, for the cyclic exchange
of time-critical IO user data, PROFINET IO does not use TCP/IP, it uses real-time
communication (RT) or isochronous real-time communication (IRT) for the synchronized data
exchange in reserved time intervals.
Fields of application of PROFINET with RT
PROFINET with RT is suited for:
•
Time-critical applications in factory automation
• The implementation of large quantity structures in line process plants