A recent poll by Control magazine shows that only 12% of users report using primarily digital buses.  Keith Larson mentioned the report in the article, “Industrial Networking: The Next 20 Years”: “…a just-completed survey of Control readers indicated that a full 54% of survey respondents still use mostly 4-20mA analog hardwiring for instrument communications. Only 12% reported using primarily digital buses.”

I wish I knew if they were talking about their existing infrastructure or new projects.  If new projects, then I am really baffled.  Fieldbuses have been around long enough (PROFIBUS started over 20 years ago) and are widespread enough (over 24,000,000 PROFIBUS nodes installed so far) that this should be an easy decision.  Is it that there are too many choices?  Well, in North America there are really only two choices in each category:

   Discrete: PROFIBUS DP or DeviceNet

   Process: PROFIBUS PA or Foundation Fieldbus

   Industrial Ethernet: PROFINET or Ethernet/IP

PROFIBUS  DP and PROFIBUS PA have different physical layers, but use the same protocol.  PROFINET easily integrates with PROFIBUS and other networks, too, including DeviceNet and FF.  To me the choice of all PROFI looks easy, but I may be ever so slightly biased.  So don’t take my word for it – try both choices.  Pick a couple small projects, educate yourself about both alternatives, then implement both. This requires some time commitment, but it’s better than staying stuck in the past.  I’m pretty confident which technology will win the comparison. 

“If you do what you’ve always done, you’ll get what you’ve always gotten.”  If your facility will not benefit from easier installation, faster commissioning, quicker troubleshooting, and more uptime then by all means keep use hard wiring.  If it will, then get on a bus!