On the road again…

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The General Assembly Meeting ended Thursday night with the traditional pool party.  Friday morning I took off for the next PROFINET one-day training class in Austin. (Ok, truth in traveling, my wife came along and we met our youngest and his family at Sea World in San Antonio for the weekend.)

The Training Session itself had an unusually high percentage of device manufacturers present including some who were at the PROFINET Developer Workshop (PDW) the week before.  At the PDW, they learned how to get help developing their PROFINET products and a very brief overview of PROFINET.  At the one-day training event they received a more-detailed look at PROFINET itself complete with demos and detailed application stories.  If you missed these, the next PROFINET one-day training event is in Detroit on September 19 and the next PROFINET Developer Workshop is in Boston on October 23. 

I discovered two surprising things at this event: one good, one puzzling.  The good: go out the ballroom entrance from the hotel and in two minutes you can be at Amy’s Ice Cream.  (Dark chocolate ice cream with dark chocolate chunks; high in antioxidants and very healthy.  Delicious, too.)   I love Amy and look her up every time I’m in Austin or Houston.

The puzzling thing, a comment on a course evaluation form: “Standard Ethernet is not IEEE 802.3.  The frame formats are different.”  Putting our collective engineering heads together and consulting the history books, we concluded that this is still puzzling.  In the mid-70’s when Ethernet was invented, it ran slower, was CSMA/CD, used coax, and had a smaller address space.  So the frame was different then.  In 1980 co-inventor Bob Metcalfe had started 3Com and convinced Digital, Intel, and Xerox to update speeds and address space and specify a type field – the DIX standard or Ethernet Version 2.  You will find more detail in the Wikipedia Ethernet article.  The important point is that the two versions coexist on the same network.

The main point we make about PROFINET and Ethernet is that PROFINET uses Ethernet (yes, Standard Unmodified Ethernet – SUE).  If you put a sniffer like Wireshark on the network and look at the Ethernet frames used by PROFINET, you find that they are standard Ethernet frames, even for motion control.

Insights, corrections, and comments are welcome on: “Standard Ethernet is not IEEE 802.3.  The frame formats are different.”

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