PROFINET: 6 Little Known Facts and Why They Matter

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There are some well-known facts about PROFINET.  Most people know them:  PROFINET is suitable in the three major application spaces: factory, process, and motion control.  PROFINET is fast.  PROFINET is complete.  Part of what makes PROFINET complete is “the little known things.”  Here are six features (“little things”) of PROFINET that you probably were unaware of:

  1. iPar Server.  What if there were a repository for configuration data that would make it easier to replace a device and recover its configuration?  iStock_000014937781SmallThere is.  It’s called the iParameter Server, iPar for short.
  2. TCI.  TCI is the acronym for Tool Calling Interface.  It enables a drive vendor’s configuration software to be accessed from (and exchange data with) the programming software.  More information is available in the white paper, Tool Calling Interface.
  3. I-Device.  How can I get data from one controller to another?  If you guessed I-Device, you are correct!  I-Device makes one PLC look just like IO to another PLC.  So the familiar means of communication are available, including PROFINET Real-Time for fast updates.
  4. Shared Device.  There’s an IO rack already installed.  Now you need to add a new PLC and more IO.  Do you have to add a new IO rack?  No, not if there is space in the existing one.  Shared Device allows one IO rack to have modules controlled by different PLCs.  This saves the price of a new IO rack.
  5. Uses TCP/IP.  TCP/IP is just a software stack that takes incoming Ethernet frames and directs them to the appropriate application.  PROFINET can be that application at the same time other applications are running – applications, like a web browser for viewing Ethernet switches’ configuration pages.  PROFINET Real-Time data skips TCP/IP to avoid its detrimental impact on speed and determinism, but PROFINET uses TCP/IP for configuration and diagnostics.  Both kinds of Ethernet frames happily coexist on the same cable.
  6. Uses standard Ethernet switches.  There was an ugly rumor going around that PROFINET requires special, “proprietary” switches.  Like many rumors, there is a germ of truth in there somewhere. In the case of PROFINET, if it is used for motion control or very high-speed IO, a hardware implementation is required in the switch to achieve the needed speed.  So for that single-digit percentage of the market you need a “special” switch.  It’s not proprietary though; many vendors make them.

Download the PROFINET Technical Description for more information about PROFINET, including the “little known things.”

–Carl Henning

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