Wednesday, 25 February 2009

There are Simultaneous Equipment and Recipe procedural elements

This was recently stated on the Part 5 Blog
"In some cases it may be sufficient to allow the recipe phase to directly control the equipment modules. In other systems where complex equipment modules exist, it may be necessary to implement some level of state model based procedural control in the equipment between the recipe phase and equipment modules in order to better deal with the underlying equipment complexity. Again, it’s an implementation decision left to the developer and thus does not restrict creative efforts."

I don't agree. The Equipment Phase must exist 'in' the equipment. Allowing "the recipe phase to directly control the equipment modules" is not a concept I can subscribe to.

I am assuming in the following a phase level interface for simplicity, but it could be Operations or higher.

The Recipe Phase is that procedural control that speaks to the Equipment Phase, it may just be one step in an operation, which interfaces with the Equipment Phase but does not actually control the equipment module (or Unit) - that is the job of the Equipment Phase. But in my view (and others) both the recipe phase and it's corresponding Equipment phase exist

To further illustrate, suppose we have a PC based batch manager executing the Recipe Procedure (so the PC is the recipe controller) and it speaks to the equipment controller (eg PLC or DCS controller) then the Operation and its steps and Transitions are coded PC, whilst the steps and transitions in the Equipment Phase are coded in the Controller.
These corresponding phases speak to each other via a Phase Logic interface and some data transfer such as recipe parameters

Now, it may be that there are applications of PC Batch managers where some of the equipment control steps and transitions are coded in the PC. That just means that the recipe and equipment control are not nicely separated in the implementation, but they still both exist.
And the S88 standards are not supposed to be about actual implementations, just the concepts and models.

Wednesday, 4 February 2009

S88 Working Draft 5 Version 4

This seems to be an incredibly complicated document with no explanation of the reasons for it, or the rationale behind the various concepts that it tries to present.
Why do Automation objects need to contain Functional Manager or a Resource Manager?
A PID controller (a good example of an automation object) is something that has been in existence for around about a century, and it never needed such things, what is the reasoning behind making it so complicated?

Some internet travelling experiences

I know this blog has been silent for too long, I have been travelling, in fact I still am, this comes from New Zealand, where the connection is excellent. I thought I would share some internet travelling experiences:
The Motel in Brisbane that advertises Free internet.
On arrival the person in reception asks for your laptop and then types in the password, taking care to prevent the password being saved. When you close your laptop lid and it shuts down or hibernates the password is required again when you restart.
Reception closes at 8pm (I immediately cancelled my reservation and moved out when I found this, fortunately before 8pm)
The Hotel in Sydney that charges $30 (AU) per day
The hotel that has a third party that provides WIFI. The signal is strong, but the performance is unusable, the third party, (, said that there was no problem with their systems. Ha !
And finally using the internet with a mobile phone connected to a laptop via Bluetooth. I can tell you that at least with VodafoneAustralia it works well. But can you believe £10 per Megabyte. That means it can cost about £1000 per hour. At the same time you can get 5Gbyte per month for about £20 if you have a local account. Legalised robbery