Siemens SIMATIC ET 200AL System Manual page 1587

Description
2.1 Introduction to PROFINET
IO communication via PROFINET IO
The inputs and outputs of distributed I/O devices are read and written by means of
PROFINET IO using what is referred to as IO communication. The following figure provides an
overview of IO communication by means of PROFINET IO.
A IO controller - IO controller communication via PN/PN coupler
B IO controller - I-device communication
C IO controller - IO-device communication
D Direct data exchange between S7-1500-CPUs
Figure 2-3 IO communication via PROFINET IO
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PROFINET with STEP 7
Function Manual, 05/2021, A5E03444486-AL