Basic Terminology Of Communication - Siemens SIMATIC ET 200AL System Manual

Description
2.1 Introduction to PROFINET
IO communication via PROFINET IO
Table 2- 1 IO communication via PROFINET IO
Communication between ...
IO controllers and IO devices
IO controller and I-device
IO controller and IO controller
See also
Communication (http://support.automation.siemens.com/WW/view/en/59192925)
Network security (Page 38)
Functions (Page 113)
2.1.2

Basic terminology of communication

PROFINET communication
PROFINET communication takes place via Industrial Ethernet. The following transmission
types are supported:
● Acyclic transmission of engineering and diagnostics data and interrupts
● Cyclic transmission of user data
The PROFINET-IO communication takes place in real-time.
For additional information on the real-time communication, refer to chapter Real-time
communication (Page 173).
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Explanation
The IO controller sends data cyclically to the IO devices of its PROFINET IO system and
receives data from these devices.
A fixed quantity of data is transferred cyclically between the user programs in CPUs of IO
controllers and I-devices.
The IO controller does not access the I/O module of the I-device, but instead accesses
configured address ranges, i.e. transfer ranges, which may be located inside our outside
the process image of the CPU of the I-device. If parts of the process image are used as
transfer ranges, it is not permitted to use these for real I/O modules.
Data transfer takes place using load- and transfer operations via the process image or
via direct access.
A fixed quantity of data is cyclically transferred between the user programs in CPUs of IO
controllers. A PN/PN coupler is required as additional hardware.
The IO controllers mutually access configured address ranges, i.e. transfer ranges,
which may be located inside or outside the process image of the CPU. If parts of the
process image are used as transfer ranges, it is not permitted to use these for real I/O
modules.
Data transfer takes place using load- and transfer operations via the process image or
via direct access.
PROFINET with STEP 7 V15
Function Manual, 12/2017, A5E03444486-AH