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Profinet Communication

PROFINET (“Process Field Network”) is differentiated into different performance classes to address various timing requirements: PROFINET RT for soft real-time, or no real-time requirements at all, and PROFINET IRT for hard real-time performance. The technology was developed by Siemens and the member companies of the PROFIBUS user organization, PNO. The Ethernet-based successor to PROFIBUS DP, PROFINET I/O specifies all data transfer between I/O controllers as well as the parameterization, diagnostics, and layout of a network.

How It Works

In order to cover the different performance classes, PROFINET makes free use of the producer/consumer principle and resorts to various protocols and services. High-priority payload data sent directly via the
Ethernet protocol travels in Ethernet frames with VLAN prioritization, whereas diagnostics and configuration data, for instance, is sent using UDP/IP. That enables the system to achieve cycle times of around 10 ms for I/O applications.

Clock-synchronized cycle times below one millisecond, as required for Motion Control applications, are provided by PROFINET IRT, which implements a time multiplex mode based on specially managed, hardware-synchronized switches. So-called Dynamic Frame Packing (DFP) will in the future give users a new PROFINET variant designed to optimize cycle times making use of the summation frame principle for a certain set of devices in the network.