Best practices for deriving operator graphics from P&IDs?
Developing appropriate operator graphics is an important implementation task, and developers often have little more than the piping and instrumentation diagrams as starting point. Are there any existing best practices/methodologies for driving the displays development process?
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Grey Scale Graphics
There are several sources of information that are quite good references:
1- The High Performance HMI Handbook (Bill Hollifield)
2- Effective Operator Display Design: Asm Consortium Guideline
3- EEMUA 201 - currently being revised
Looking forward, we are also working on ISA101 which should provide a nice summary of guidelines across our industry.
Another effort that is underway is research at the Center for Operator Performance (COP) at Wright State University. Our initial findings, which are also echoed in the three references above, is that color alone is not the most important element. As part of the overall design other factors such display navigation, display hierarchies, and purpose of the displays must be taken into consideration.
Using operators to help design displays is important (I would not recommend having the operators perform the overall display system design - you need someone who is a designer involved to ensure that the overall display system works as a whole).
Operator Graphics
One of the better practices is to use an experienced operator to have a major say in the development of operator graphics (or better yet is to train the experienced operator to develop the displays). There is a lot of acceptance by other operators of how the displays look like. They do have similarities in how the equipment is laid out in the field and how they operate. On a successful project the operators who participated in the development of the graphics take the ownership of the displays even today (eight years after the project was complete).
Operator graphics from P&IDs - bad idea but everyone does it
P&ID's are not designed for operational purposes, for example they are full of clutter such as nozzle sizes that are not relevant to the control, or even the plant operators. They are usually a poor basis for control system graphics. And standards vary hugely.
P&ID's are not object oriented in any way. For example where are several identical units (ie one Unit Object) designers still mostly draw one P&ID for each. If you are lucky. Sometimes you will find more than one unit (say 2 and a half) on one P&ID or one unit defined on 2 or more P&ID's!
P&ID's totally fail to represent procedural functions
Using the S88 Hierarchy can be much better, as I have mentioned here
www.s88control.blogspot.com/search/label/HMI
Francis
www.controldraw.co.uk
Francis
www.controldraw.co.uk