Long Beach Process Q & A

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From the plane bound for Louisville, here is one of the comments from the PROFIBUS in the Process Industries one-day training class in Long Beach: “I think PROFIBUS is more complicated than Foundation Fieldbus as far as device connections go.”

At the physical layer there is no difference between FF and PROFIBUS PA so the author of this comment must have meant something else – perhaps that an FF segment can connect directly to a controller while a PA segment must connect through a DP segment.  Let’s look at an example to understand this difference:  Let’s suppose there are a couple dozen instruments to interface.  For FF there are two choices: run two or more segments back to the controller or use FF HSE with two or more linking devices back to the controller.  The latter would likely be used if the instruments were geographically separated.  For PA you could use potentially just one segment connected through a PA/DP link with the DP segment connecting to the controller.  (In general, you can have more PA devices on a segment than FF devices.)  So, in this example, there are likely fewer linking devices with PA.  In both cases there are discrete IO to interface as well.  In the FF case, you need a second, non-FF network to accomplish this.  With PROFIBUS, PROFIBUS DP already has thousands of discrete devices available.  With FF you need the second network, its interface card in the controller, its configuration and diagnostic software plus the training for plant staff on the second network.  With PROFIBUS, you already have everything you need – no additional hardware, software, or training required.  For further insight into these differences, see the White Papers on our website.

I started this on the plane to Louisville for the PROFINET one-day training class and now I’m finishing it sitting in the Louisville airport waiting for the flight home – where does the time go?  More Q & A to come… from Long Beach and then Louisville.

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