PROFINET Uses Standard Ethernet!

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Because Atlanta was our first PROFINET one-day training class of 2010, I sent out a short follow-up survey.  One of the interesting comments from that survey: “I think it is important for device manufacturers to know when they can use a generic Ethernet MAC ASIC (or FPGA) and when they cannot. Don’t hide this. It is very important to understand.”

So to emphasize this point for device manufacturers:

If you are not doing motion control, you can use a generic Ethernet MAC ASIC or FPGA.

   MAC = Media Access Controller

   ASIC = Application Specific Integrated Circuit
   FPGA = Field Programmable Gate Array
   These are two chip-based solutions and can be used for many different purposes.

PROFINET uses standard Ethernet, so standard Ethernet components and devices work just fine (until you do motion control).  Even Ethernet switches from Best Buy.

Even when you do motion control, PROFINET just uses Ethernet, but you need to implement time synchronization (IEEE1588) and provide bandwidth reservation.  And for speed purposes, you need to implement those in a chip.  We call this Isochronous Real-Time (IRT).  Iso- meaning equal and -chronous meaning time – so, equal time; the time control needed to synchronize all the devices’ clocks for bandwidth reservation.

So, most of the time you can go generic.  But just because you can do a thing does not mean you should do a thing.  So, you can use standard Ethernet ASICs or FPGAs but there are benefits to use custom chips.  Having all the communications code in one custom chip means you can let your regular CPU handle just the functions your product does.  There are many suppliers of communications chips with PROFINET built-in and more suppliers coming.  The number of chip suppliers should give you the hint that the technology is not proprietary.  PROFINET is an open standard available from IEC.

PROFINET just uses standard Ethernet!

–Carl Henning

3 Responses to “PROFINET Uses Standard Ethernet!”

  1. Howard Evans

    This issue is not even clear among Siemens’ employees. Just recently I was told that I had to use a Profinet chip (which Siemens would gladly sell to me) in order to incorporate Profinet IO functionality in our devices. I thought that wasn’t correct so after digging around Siemens’ own web site, I pointed out to them that they sell a development kit for doing Profinet IO on a standard MAC. Looks some of the misinformation that you are admonishing people for is coming from within Profinet’s own camp!

  2. chenning

    Part of the problem is that the PROFINET camp is a big camp! There are many non-Siemens chips and stacks. Give me a call at the PTO offices and I’d be glad to help.

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