I recently took part in a Fieldbus Foundation presentation given by an engineering company that is currently involved in implementing a very large fieldbus foundation system (Approx 2,500 end
devices). They are facing a number of real world challenges. One of them will be Factory Acceptance Testing (FAT).

Historically on 4-20 mA systems a certain percentage of points (10% to 100%) have been stimulated during FAT. Control, display
and alarm response is then tested. The fact that each device on the fieldbus segment must be tagged and addressed correctly creates a challenge doing this. There is discussion that the FAT may be waived and the testing done at site (SAT).

It's interesting that software project implementation these days seems to be all about testing, testing and testing. Given the
increased level of software/networking in control systems I would suggest we need to be doing more testing during development not less.

What experiences are out there that could help this project? How have large profibus systems dealt with this issue?

 

Yes, testing and qualification is an issue which has been brought to public view many times in the past. In 1998 (?) I published an article in the ISA journal about a job Kaneka Engineering did in Malaysia. Unfortunately, they edited it heavily, so the information was considerably refined for their purposes.

If you want a copy of the pdf article, or if you want to get more specific information about how our customer -- the engineering company -- actually did the implementation, please contact me direct by email.

Kaneka said, at the time, "Because this was a first for us, we made sure to give adequate time for the FAT stage and the SAT stage." They also
highlighted the major issue of fieldbus in terms of its implementation by commenting that "Since the network performance directly affects the system performance, we need to identify universal criteria for designing Fieldbus networks."In terms of the FAT and SAT, Kaneka said: "Who should take the lead for multi-vendor systems? Who should take responsibility for making
the whole system run?" They added: "We also need firm procedures for the FAT and the SAT, especially to fix procedures for loop checking. We also need to know how to check cabling as digital communication circuits, after all
cabling works are complete." And: "We navigated a period of trial and error to find the best network configuration. Variables which needed to be decided were, for example, cable length and network schedule."

Regards,
Matthew Yamatake Tokyo
[email protected]
http://www.yamatake.co.jp