Tuesday, 10 March 2009

Equipment Procedure or Recipe Procedure?

I see that the latest draft of the updated part 1 spends a lot of words on Equipment Procedural Entities (Phases, Operations, Unit Procedures)
I think that this results from the idea that the recipe to equipment boundary is the same as the boundary between a recipe manager and an equipment controller.

My take on this is that if the 'equipment controller' has the capability of containing higher level procedures such as operations that do no more than sequence lower level ones such as phases then this means that the  controller is actually performing some part of the recipe control. And as such this is not equipment control.
If this concept were adopted, then the entire standard could be greatly simplified, and I think without losing any value.

I propose that the only function that an Equipment Procedural entity can perform is one that actually directly controls(or directs) equipment, for example a phase that sends commands and responds to to basic control.

For a bit of background on this, when I first had ControlDraw working properly, soon after the introduction of Version 2 and the object structure that exists to this day I dithered about whether there should be a separate Class for Equipment phases and Recipe Phases. 
I decided not to, as I found that the only difference was in their owners (in ControlDraw that is the Parent object that links to the Phase diagram.)
So, if you have a phase in a Recipe procedure that is not also in an Equipment item then it must be purely a  procedural phase, if it does exist in the equipment then it is an equipment phase. If in both then it is still an equipment phase, but is referenced by the corresponding Recipe Procedure phase.

No comments: