Siemens SIMATIC ET 200AL, System Manual

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Functions
5.13 Accelerating startup
PROFINET with STEP 7
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Function Manual, 05/2021, A5E03444486-AL
Properties of ports
PROFINET devices have the following two types of ports:
Type of port PROFINET devices
Switch port with crossed pin assignment For IO devices: Port 2
For S7-CPUs with two ports: Ports 1 and 2
Terminal device port with normal pin assign-
ment
For IO devices: Port 1
For S7-CPUs with one port: Port 1
Crossed pin assignment means that the pin assignment for the ports for sending and
receiving between the respective PROFINET devices is inverted internally.
Validity of the cabling rules
The cabling rules described in the following paragraph apply exclusively for the situation in
which you have specified a fixed port setting in STEP 7.
Rules for cabling
You can connect several IO devices in series using patch cables. To do this, connect port 2 of
the IO device (distributed I/O) with port 1 of the next IO device. The following graphic
provides an example with two IO devices.
Figure 5-115 Optimized cabling for accelerated startup
5.13.6 Measures in the user program
Introduction
You can make certain changes in the user program to accelerate the startup for IO devices of
docking systems that alternate during operation.