Friday, 6 June 2008

Recipe Control

I see that Dave has blogged about Recipe Control

"No where that I can find does the ISA88 standard deal with “Recipe Control” as it does with “Equipment Control.” it says. My jaw dropped when I read this so I posted a fairly mocking response, but as usual it takes days before comments on that 'blog' appears if at all.

I think that the post indicates that the most fundamental purpose and meaning of Part 1 is not understood by the poster. Let me explain why I say that.

The entire Original Part 1 is all about Recipes and how to make stuff according to a Recipe.
And keeping the Recipes independent from the equipment and yet being able to run the recipes in the available equipment. The Equipment gets Controlled Yes. The Recipe provides the Set Points and the Procedural Sequence, but the Equipment Does the Control!

Part 1 quite rightly strictly excludes defining how to program either recipes or the control of equipment. Part 1 as it is does a very valuable job of providing a framework in terms of the words that can be used, and models that can provide a structure where those words can be used to describe the required Recipes and the Equipment Control.

Recipe Control is a meaningless term - unless we are talking about how to manage the Recipes themselves. Such as making sure that they are kept safely, version management, ensuring that a Recipe is up to date and approved for use etc.

When thinking about Recipes, it always helps to use the cooking analogy. So what do the cook books say about Controlling a Recipe. Try Searching for Cooking Control. Did that help?

By the way, Dave's 'blog' is not really a blog, but never mind. If you comment on this one it will appear - immediately, please feel free.

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