Monday, April 8, 2013

InTech Article on Fieldbus Project Commissioning

This month's InTech has a great article about fieldbus project commissioning written by Augusto Pereira and Ian Verhappen.  Augusto and Ian have done a lot of fieldbus projects and they have written a good book on fieldbus that is available through ISA at their bookstore.  In this article they give some good tips on necessary equipment for your fieldbus installation, commissioning practices, and they have some interesting things to say about fieldbus network diagnostics.  Key takeaways are you can save yourself a lot of time by investing in registered products, including cable, and follow a few simple rules to keep your installation painless.

Projects Commissioning with Fieldbus Foundation


  1. I would like to stress that the procedures and documents to ensure a successful commissioning and certainty of outcome for a project involving fieldbus are available. See for example the AG-181 engineering guideline:

    The document not only provides new procedures, but also guides where old analog procedures for 4-20 mA and on/off signals are no longer required; such as using simple plausibility check in lieu of five-point loop test – overall simplifying commissioning.

    You can port the pointers in the guideline to your corporate document format. Independent consultants and PMC with experience from prior projects are able to assist and may have their own documentation ready. Most EPC contractors and consultants by now have also developed their own work processes and training for fieldbus design, installation, and commissioning.

    This way you can minimize risk, provide full functionality, and ensure reliable communication, such that installation can be handed over on time, and provides high availability for a long time.

    Simple fieldbus testers like the Relcom FBT-6 are easy to use, even easier than a multi-meter in my personal opinion, speeding up troubleshooting by detecting problems. Proper tools provide a quick solution to problems that may be encountered during commissioning. There are also expert tools as shown in the article. Relcom also provides a troubleshooting guide which can help in the quick resolution of problems:

    Make use of these fieldbus procedures and tools. Simple visual inspection of the installation is often the most powerful “tool”

    Use registered fieldbus cable to ensure noise rejection and preventing signal distortion, protecting the bus, preventing communication errors, in turn ensuring reliable operation.

    Project benefits seen from fieldbus include reduced I/O cards and wiring, reduced device count, elimination of proprietary protocols, and faster commissioning. The operations & maintenance benefits from fieldbus includes high signal integrity, high signal fidelity, tighter control, signal status in real-time, more powerful devices, more device diagnostics, and online upgrades. With the commissioning done right, these benefits can materialize and be valuable.

    Jonas Berge

  2. I think this kind of article scares people away from fieldbus. Fact is the source of the problem is very uncommon. Most projects buy their fieldbus cable from one vendor, and the same cable is used throughout the entire project. Lesson learned here is the procurement guy that bought the blue cable should be put back in charge of buying office supplies. This hardly justifies "Segment Certification." So the rule is buy certified physical layer components, and devices. install the cable properly (i.e. single point grounding), and use the FTB-6 to sniff out problem segments. If they have used our (MooreHawke) device couplers with end of line auto-terminators, the only physical layer problems may be with a few loose connections and/or defective devices. Unfortunately, this article leaves you with the feeling that you have to deal with (i.e. certify) the physical layer of every segment. As you know, in reality there is a very simple procedure for testing the cable and shield and then applying fieldbus power and installing devices. Works 99.9% of the time. Harry Wilson