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

Functions

5.5 Real-time communication

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 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
192
Real-time communication performance
PROFINET with STEP 7
Function Manual, 05/2021, A5E03444486-AL