Friday, July 19, 2013

Tom Moore of IMS Research Clarifies their Position on Ethernet vs Fieldbus

IMS Research, now part of IHS, recently published a market forecast report that looked at the future of various fieldbus protocols and the growing role of Ethernet in industrial networks.  That report caused quite a stir in the industry because it seemed to predict the imminent downfall of fieldbus, which would in the future be replaced with "Ethernet".  Of course, the terms "Ethernet" and "fieldbus" are not mutually exclusive, and I had some commentary and analysis of my own that you can read in this blog post.

Now, IMS research analyst Tom Moore and author of the report, has some clarifications about the IMS research findings and states the following in a recent blog post that you can read here:
"Although the research findings questioned the long-term sustainability of fieldbus in certain applications, we certainly haven’t forecast the impending doom of the technology.  In fact, new fieldbus node connections will continue to grow healthily to 2016.  From a recent IHS press release, “The future is strong for fieldbus, with new connections still increasing year-on-year.  The growth rate for new fieldbus nodes is forecast to be just over 9 percent to 2016.” 
Personally, I do not think it was the intention of IMS Research to foretell the doom of fieldbus, and if you look at the actual numbers presented in the report it does show continued growth for fieldbus over the next several  years.  The problem in my opinion is that people tend to latch onto the term "Ethernet" and view it as a panacea for everyone's network requirements.  Yes, many plant networks today, even FOUNDATION fieldbus HSE, are  based on Ethernet.  So, the discussion is not one of "fieldbus versus Ethernet".  It is rather a discussion of Ethernet and standard IP-based networks in automation versus other networks.

IMS Research Analyst Blog: Ethernet vs. Fieldbus - What does IHS really see happening?

1 comment:

  1. The real groundswell out there is not from fieldbus to Ethernet, but from hardwired analog 4-20 mA and discrete on/off signals to digital communication networks. If it will be fieldbus or Ethernet is secondary. In my personal opinion, Ethernet is great for the control network at level 2 of the Purdue reference model, as well as the MES and ERP levels above. Ethernet is also taking hold for drives, motor starters, MCC, wireless gateways, and small package unit PLC at level 1-1/2 of the Purdue model – eating into the “H2” level of fieldbus. I guess for this reason the Fieldbus Foundation dropped the development of H2 and went straight for Ethernet: HSE at this intermediate level. As far as sensors/transmitters and positioners/actuators/valves at level 1 of the Purdue model these mainly use hardwired analog 4-20 mA and discrete on/off signals. We need digital communication down to the sensors and actuators too. I see a little bit of Ethernet used in magnetic and Coriolis flow meters as well as electric actuator / Motor Operated Valve (MOV). However, Ethernet is struggling to take the place of 4-20 mA and on/off signals. For digital communication with intelligent pressure, temperature, level, and interface level transmitters, vortex flow meters, as well as pH , conductivity , and amperometric analyzers as well as control valve positioners, and intelligent on/off valves at level 1 of the Purdue model I do not see any Ethernet. Instead, at this lower level, plants should use one of the “H1” level fieldbus protocols to provide digital communication all the way including the “first meter”. Important characteristics of “H1” fieldbus include long distance, passive field junction boxes not requiring power supply, two-wire bus power, intrinsic safety, and robust connections etc. Indeed fieldbus and Ethernet complement each other to eliminate hardwired 4-20 mA and on/off signals.