Figure 1: Profinet network
A Profinet network comprises at least one I/O controller and one or several I/O
devices. As an option, an I/O device can exchange date with several I/O controllers
(shared input and shared device function). An I/O supervisor is often only available
on a temporary basis for commissioning and programming. In turn, for continuous
diagnostic and status monitoring the I/O supervisor is integral part of a Profinet
installation.
2.2. Profinet basic functions
An I/O controller reads the input information in cyclic intervals from the I/O devices
and writes the output information to the I/O devices. In addition to this cyclic data
transfer of the process representation, Profinet also provides powerful functions for
diagnostic and commissioning as well as event based alarm treatment in real time.
Data transfer is monitored via the monitoring function at I/O controller and I/O device
level.
2.3. Communication technology
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Full duplex , 100 Mbit/s switched Ethernet (100BASE-TX) IEEE 802.3
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Wiring according to IEC 61784-5-3. Cable with twisted wire pairs for each dir-
ection RX and TX
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Simultaneous communication into both send and receive direction
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Ethernet switches coordinate data transmission and prevent collisions on the
cable.
2.4. Bus access
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Switched Ethernet with flexible priority control, no collision domains, no coordin-
ation of the network access required – all participants have simultaneous access.
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Data exchange in compliance with provider consumer model:The provider (I/O
device) supplies process data to one or several consumers (I/O controllers).
●
The maximum number of Profinet I/O devices per network depends on the I/O
controller implemented.
2.5. Topology – Profinet device network configuration
Profinet is characterised by the virtually free topology implementation. If the required
response times of messages for the automation application are exceeded, the
maximum network depth – the number of cascaded Profinet participants – have been
reached.The maximum distance between two network participants is 100 metres.
7
Actuator controls
AC 01.2/ACExC 01.2 Profinet General information on Profinet
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