When engineering a project with Foundation fieldbus, one element to consider is the electrical loading on each segment. I received an email the other day asking:
…to find required formulas to calculate FOUNDATION FIELD BUS loading… I am using [brand X] product and I have come across a web site that you can provide information. If you have those formulas… it would be nice if you could share them.
I also did some Googling around, and saw a few things, but did not see our Emerson Segment Design Tool listed in the search results, at least not in the first few pages. The segment design tool development team released version 5 of this tool in September, just before the Emerson Exchange meeting.
Here’s a bit about what this calculator tool does:
The Segment Design Tool is a Windows 98/NT/W2K/XP compatible program designed to provide a general guide for reducing the time required to engineer a Foundation fieldbus H1 segment for the DeltaV system, Ovation system and the Rosemount 3420 Fieldbus Interface. The Segment Design Tool checks the segment layout utilizing the Fieldbus Foundation‘s guidelines governing cable lengths, power consumption and proper segment termination. This tool now supports a variety of hazardous area protection techniques, including FISCO, FNICO and Entity Concept for Intrinsic Safety.
One of Emerson’s Fieldbus consultants, Dan Daugherty, whom you may recall from earlier posts, helped me find the URL for this tool. He also added this bit of wisdom that I passed back to the person who originally emailed me:
My advice for people who can’t find an exact match in the Segment Design Tool’s component library for their cable or other components is to find something close and then use enough design margin that it won’t matter if it isn’t exact.
I’ll also pass along that the segment design tool team invites comments and questions. Feel free to take them up on their offer, or leave a comment on this post, and I’ll pass it along to the team.