More on ISA S.5.06 Functional Requirements

I have spent some time delving into this standard, and the examples it provides.
Further than that, I have now created a ControlDraw model that captures basically everything that the standard shows. This is for me the best way of understanding a process.


One thing that amused me about the batch reactor example is that it has nowhere to send the batch it makes apart from down the drain! It calls dumping the product down the drain the Dump Phase, part of the Transfer operation, I suppose dump is appropriate, but Transfer? Maybe I missed something - here is the P&ID




S5.6 has this thing called a Sequence matrix. This is a condensed overview of the example process, but I suspect that it really would not be workable when scaled up to a real, and more complex process. Furthermore it conflates too much into too little, and if you are trying to do in in Excel demands lots of formatting. ( And the example manages to avoid the most complex issue, the transfer.)

So my model does not use that method - it is optional, you can also use Sequence charts - and instead uses those, in the form of SFC's and PFC's
Maybe a complex query could generate the matrix from the combination of the sequences and the equipment - it is possible but it would be a huge table compared to the example sequence matrix. Even without adding a real transfer!

Documentation Standards

There is a new standard, ANSI/ISA-5.06.01-2007 Functional Requirements Documentation for Control Software Applications.
It reminded me of an older one from Norsok, that I came across while researching control systems diagrams. I would be very interested to hear from people who are actually using this standard.

I am of course very interested in such standards, as much as I am in S88, because this is my livelyhood, as well as an abiding interest. I look at these standards to see if they have any bright ideas, such as new diagram types or models that might be added to ControlDraw.

I-005 System Control Diagram, (Rev 2 2005) - includes:

Present extensive use of computerised systems and 3D modeling provide efficient tools for specifying and handling of physical equipment in a standardised manner. However, the development of methods and tools to specify functional relationships has not reached a corresponding level.
During the plant development the process engineers specify the process through the development of the P&IDs. Throughout this work process the process engineers acquire a thorough understanding of the total plant behavior. However, the P&IDs provide limited facilities for documentation of the overall functionality as well as operational aspects of the plant.

The SCD approach has been developed with a view to industrial processes controlled by state-of-the-art process control systems, but as it provides a general process oriented approach for development of thedocuments, no field of application are explicitly excluded.

It says a lot more (Search like this)



And the ISA standard (also known as S5.6) says

Learning and configuring today's control software packages is easier than ever before. Documentation, however, is not such an easy task. With the increased capabilities of software packages to handle more process and operator interfaces, the complexity of defining and documenting these requirements increases. This standard directly addresses this documentation issue.


I have no idea whether the ISA looked at the Norsok standard when they were developing S5.6, I wish they had though. It even covers much of what S88 Part 5 is aspiring to, such as Modes and States (in some depth and with precise meanings and State Charts, templates.