Wednesday, 17 September 2008

S88 Graphics

I have seen many automation system HMI's. Often the process graphics have been produced based on the P&ID's. But P&ID's are not normally a good basis for graphics as they are not designed for operational purposes. Using the S88 Hierarchy can be much better.
There is at least one plant where the S88 Physical Hierarchy is used as the basic for the HMI graphics structure.
I believe this is a good structure, not only because it makes for simple uncluttered graphics but also because it exposes the S88 modules of a system to the operators.
Here is an example
The Plant overview shows a graphic that contains several Process Cells
Clicking on a Process Cell object opens the Process Cell diagram, which shows all the Units in the cell. Note - these can use colour and text to indicate the status of each Unit.
Clicking on a Unit object opens a Unit diagram
Note that this does not show all the valves etc in the Unit, it just shows simple objects for each equipment module but again with colour and text to highlight status of the equipment modules
Clicking on an equipment module object then opens an equipment module diagram where you can see the valves etc in the em.
From here you can also go to an Equipment Module Faceplate
Or of course a to Control Module Faceplate.
In this case, the automation for the plant was designed with ControlDraw, and the graphics correspond to relevant objects (diagrams) in the ControlDraw model.

Comments are as ever welcome.


Anonymous said...

Can you tell us how the operators like this?

1) It seems like it would take a long time to "drill down" to whatever you want to look at.
2) Manual operation of the plant would be impossible from a practical perspective. I assume the status of an equipment module doesn't reflect manual operation.

Francis said...

Actually, the status of an equipment module can reflect manual operation.

With this system, Manual Operation is actually simpler for the operator, and more reliable
Just letting the operator take direct control of the control modules (valves for example) by allowing operators to set them to manual and then drive them potentially allows the operator to put equipment into undefined states, with unknown consequences.
Instead the operator can put the entire Equipment Module (or maybe Unit) into manual and then set it to a predefined state such as filling, emptying etc.
And as such states are known in advance the system can still be programmed so that the equipment responds coherently.
*Yes, of course you can also allow more direct manual operation. So that level of manual should be discouraged, perhaps by a higher level than normal operator security setting.