Why Use a Fieldbus?

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There are two main reasons to use a fieldbus or Industrial Ethernet like PROFIBUS or PROFINET:

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  1. Save wiring.
  2. Prevent downtime.

Most users think about saving wiring as the most important reason.  Not just wiring, of course.  When you

reduce the amount of wiring, you also reduce:

  • The number of terminal strips the wire lands on
  • The labeling and terminating time
  • Enclosures to contain the terminal strips
  • The labor required

It is easy to calculate the savings and the ROI from these reductions in time and material.  There are white papers and other documentation to help you justify projects on this basis.  But I’m convinced this is small potatoes compared to preventing downtime.

Fieldbus-more-information (Custom)

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Downtime can be prevented because much more information is now available than just the measured value.  For example, PROFIBUS PA returns quality of value information and asset management information.  PROFINET carries the same information and adds the use of standard IT protocols to provide even more diagnostic information for the network itself.  The more expensive downtime is, the more that is saved by taking advantage of this information to prevent downtime or shorten it.  Sadly, far too many plants ignore this information.  Too many of us have heard a user say: “We don’t need a fieldbus anymore; no one ever pays attention to all that diagnostic stuff anyway.”  I cannot imagine that this is because downtime is not expensive there.  It’s hard to calculate an ROI for reducing downtime; is that why it’s ignored?  Were people not properly trained in how to use the asset management tools?  Maybe the people were not involved in the decision to use a fieldbus so feel disconnected?

So if you are updating a production line or a plant, ask your vendor about their asset management tools AND training.  Follow PROFIBUS and PROFINET Tech Tips.  There is a “Tech Tip Roundup” blog post.  And subscribe to PROFINEWS for additional Tech Tips every month.


–Carl Henning

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