Fieldbus Attributes Supporting Operator Confidence and Performance

by | Oct 7, 2013 | Asset Management, Event

Jim Cahill

Chief Blogger, Editor

I hope the live blog posts from last week’s Emerson Exchange conference in Texas gave you a flavor for some of the happenings. In one of the posts, 7 Ways Fieldbus Improves Operator Confidence and Performance, I received a great comment back from Emerson’s Jonas Berge and wanted to share it in today’s post:

Emerson's Jonas BergeGreat material. I have a few personal favorites of my own:

The real-time status provided by fieldbus enables process problems to be distinguished from device problems, thereby minimizing nuisance shutdowns of the control loop on sensor failure.

Transmitters are digital, controllers are digital, and positioners are digital. I personally believe it doesn’t make sense to run analog signals between them. Fieldbus does not rely on 4-20 mA which means totally digital closed loop that is and time-synchronized from end to end, from sensor to actuator. Eliminating 4-20 mA I/O cards and their associated scan delays and jitter improves control response time which in turn results in tighter control, particularly compared to remote I/O with additional network and link delays.

Doing away with 4-20 mA also does away with multiple D/A and A/D conversions. This leads to higher resolution and accuracy. Errors due to current calibration differences between transmitter output and DCS input are also done away with. This is particularly important in flow and level applications such as tank gauging. The “on-scale” errors associated with 4-20 mA signals are eliminated too.

Fieldbus gets rid of the process variable value skew that sometimes results from mismatched 4-20 mA range settings between transmitters and the control system. Measurement values are also transmitted over the full sensor limit, not limited to a narrow 4-20 mA portion.

Diagnostics not only detect outright failures, but predictive diagnostics can be used to prevent problems by reporting when ambient conditions are exceeded etc. – in real time.

Diagnostics is not just for transmitters and control valves, but also the other half of the instrumentation: discrete devices like intelligent two-wire fieldbus on/off valves and electric actuators / motor operated valves (MOV) using fieldbus also provide diagnostics. NAMUR NE107-compliant device alarm rationalization notify the right person without alarm flooding.

More devices can be added to the existing bus without laying homerun cable or using more I/O cards

These operation & maintenance benefits as well as project benefits are covered in the FF brochure.

Jonas also shared some of his experiences from Emerson Exchange in posts in the Emerson Exchange 365 community. In his post, AMS Suite / Asset Reliability Roadmap, he highlights some of the enhancements presented. Jonas also provided a thoughtful comment to the recap of the presentation, Why are there missing measurements? He notes, “…this presentation really embodies what Peter Zornio called “pervasive sensing” at the opening of the Exchange.”

Submit a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Submit a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Subscribe for Updates

Follow Us

We invite you to follow us on Facebook, LinkedIn, Twitter and YouTube to keep up to date on all the latest news, events and innovations to help you take on and solve your toughest challenges.

Want to re-purpose, reuse or translate content?

Please do, Just link back to the post and send us a quick note so we can share your work. Thanks!

Our Global Community

Emerson Exchange 365

The opinions expressed here are the personal opinions of the authors. Content published here is not read or approved by Emerson before it is posted and does not necessarily represent the views and opinions of Emerson.