Wednesday, 30 July 2008

Back on the Tea - off topic

As I was talking about cups of tea, here is The Tea Rap on YouTube

Monday, 28 July 2008

Common Resources

What are these Common Resources?

If more than one unit can acquire or request the services of a single resource, the resource is
designated as a common resource. Common resources are often present with complex batch
processes. Common resources are often implemented as either equipment modules or control
modules. A common resource may be either exclusive-use or shared-use.

That definition is pretty good for me, but there is still disagreement, and to a degree I think that they are the bits where the original S88 parties could not agree. For example, some give the example of Storage Tanks, but in an alternative perspective (not just mine) Storage Tanks are Units.

Another good example is transfer systems. Surely these are common resources?

Actually some of the best batch implementations I have seen treat them as units. They call them X units, but as far as controlling them they are exactly the same as 'normal' Units, including having Equipment Procedural Elements.
The viewpoint once described to me was that if contains even part of the batch it then it is a unit.

Something like steam supply or other utilities are for sure common resources aren't they?

Can a resource be a Unit and a Common Resource?
So, is there any prospect of the revised part 1 coming up with an improved wording that will stop the divergent interpretations, of things like storage tanks, transfer systems?

Of course, the definition that CR's may be made as equipment modules implies that they can have EPE's, and take part in recipes.
To be continued

Friday, 18 July 2008

Unit State Model

Latest on Part 5 developments
What is a Base State Model?
It says. The Base State Model defines a complete fixed set of defined unit states, unit state commands, and unit state transitions. Each Equipment Unit Procedure will comprise a subset of the same base sta...

This dates back to 1996, it works well. It integrates exception handling with Unit Control in ways that the conventional S88 Procedural States do not.