Real-Time Communication; Introduction - Siemens SIMATIC ET 200AL System Manual

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 5-44
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
PROFINET with STEP 7 V15
Function Manual, 12/2017, A5E03444486-AH
Real-time communication performance
Functions
5.5 Real-time communication
173