Frede Vinther, NNE Pharmaplan A/S, gave a recap presentation of his presentation at WBF-Europe last fall.
He described the similarities and differentiation between batch software packages.
Batch has been around forever, long before S88
There are limitations in ISA-88. One batch limited by the extent of a Process Cell. One process cell may run several Batches, but there is a maximum of 4 procedural levels. Only one operation can be active in a unit. Modes and states may be defined. There are two main architectures-- procedural and equipment control in DCS type systems or BES combined with PLC systems. Both provide the same end user production functionality.
The similarities in the packages...they all do recipe management, PFC, equipment control, Procedural-Equipment linking on the phase level only. They all do modes and states, and collection and reporting sytems.
Where they differentiate, is that there are a very few systems where you can link your recipe unit procedure to equipment unit procedure. There are a few systems that allow you to have more than the four levels deviced by ISA-88. You can find a package that allows the equipment phase to continue during recipe phase step chagne. Some systems allow propagation of States inside the scope of a Unit. Afew ssytems allow the capability of defining specific execption procedures and include these in recipes as PFCs. Some have the capability of defiining failure monitoring on the Equipment Phase. Some have infrastructure for Equipmetn Modules. Few have the capability of defining prodedure entitites for execution of human controlled process acitons, and some few have the capability of executiog the control recipe down into the controllers/PLCs.
He showed several cases to illustrate the problems with batch. Case #1 is a speed of control case.
This is a coating process that requires fast Phase transition. Phases: Dosing, spraying and Drying with process duriation of 20-30 seconds (Phase Run Time)... the problem is taht change from one Phase to the next takes long time: 10 to 120 seconds and it is architecture dependent...and it is very hard to keep it consistent.
Case #2, is a coating process with flow, temperature and humidity control of air. Vinther showed how it should be modeled, and what the limitations of S88 software are.
Case #3 is combining automation control and human actions. Many process require human interaction: charging of ingredient, sample taking, etc. In this example, we have to put a batch message out: "Add 20 kg of salt, and click here when done." Vinther showed a solution that he feels is compatible with S88...but it isn't approved according to the standard.
ISA 88.01 has been available for more than 10 years, an it has provided a very good methodology and definition, but there are still problems.
We need integration of Human Process Actions into the Master Recipe and Control Recipe Execution.
We need Control recipe/eqipment control linking...
We need recipe phase to equipment phase as a 1:n as stated in ISA88 and not only as a 1:1 relation.
Production requires flexibility!
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