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12 PROFINET
PROFINET is the innovative open standard for the implementation of end-to-end integrated auto-
mation solutions based on Industrial Ethernet. With PROFINET, simple distributed I/O and time-crit-
ical applications can be integrated into Ethernet communication just as well as distributed automa-
tion system on an automation component basis.
Distributed I/O with PROFINET IO
Distributed I/O is connected into communication through PROFINET. Here, the familiar I/O view of
PROFIBUS is retained, in which the peripheral data from the field devices are periodically transmit-
ted into the process model of the control system.
Device Model
PROFINET IO describes a device model oriented to the PROFIBUS framework, consisting of places of
insertion (slots) and groups of I/O channels (sub slots). The technical characteristics of the field
devices are described by the so-called GSD (General Station Description) on an XML basis.
Fieldbus integration
PROFINET offers a model for integration of existing field buses like PROFIBUS, AS-Interface, and
INTERBUS.
This allows the construction of arbitrarily mixed systems consisting of fieldbus- and Ethernet-based
segments. Thus a smooth technology transition is possible from fieldbus-based systems to PROF-
INET. The large number of fieldbus systems makes it necessary to support their simple integration
into PROFINET for reasons of investment protection.
The integration is done with so-called "proxies". A proxy is a device which connects an underlying
fieldbus with PROFINET. The proxy concept allows the device manufacturer, the plant and machine
builder as well as the end user a high degree of investment protection.
Communication in PROFINET
Communication in PROFINET contains different levels of performance:
The non-time-critical transmission of parameters, configuration data, and switching information
occurs in PROFINET in the standard channel based on UDP and IP. This allows the connection of the
automation level with other networks (MES, ERP).
For the transmission of time critical process data within the production facility, there is a Real-Time
channel (RT) available.
For particularly challenging tasks, the hardware based communication channel Isochronous Real-
Time (IRT) can be used for example in case of Motion Control Applications and high performance
applications in factory automation.
UDP/IP communication
For non-time-critical processes, PROFINET uses communications with the standard Ethernet mech-
anisms over UDP/IP which follow the international standard IEEE 802.3.
Similar to standard Ethernet, PROFINET field devices are addressed using a MAC and an IP address.
In UDP/IP communications, different networks are recognized based on the IP address. Within a net-
work, the MAC address is a unique criterion for the addressing of the target device. PROFINET field
devices can be connected to the IT world without limitations. A prerequisite for this is that the cor-
responding services, for instance file transfer, must be implemented in the field device involved.
This can differ from manufacturer to manufacturer.
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