What if we could build a blend of experience, standards and best practices into process control system software in a way that made it nearly impossible for an inexperienced practitioner to produce a poor quality solution? Furthermore, what if process control system software was designed to be easily maintainable by any process knowledgeable individual—not necessarily an engineer or programmer?
This would seem to be an easily achievable goal. After all, we all use the sophisticated statistical and financial formulas embedded into Microsoft Excel without needing to understand all their details and applications. Better yet, have you ever seen a smart phone standard or even a manual? Probably not, but that certainly hasn’t slowed the widespread use and adoption of those mobile devices.
Last week’s Automation World CSIA guest blog, entitled “Standards and Best Practices in the Integrator/Manufacturer Relationship” resonated strongly with me. I concur with all that was said. In fact, I found myself smiling as I read it and recalled my own experiences feeling that the word “standards” is often considered, as mentioned, a “wet blanket on the fires of innovation.”
Much of my life experience is connected with the ISA-88 standard for Batch Control. For 40 years control engineers have developed custom programs to support the control of equipment entities in an ISA-88 batch process cell and implement the state models for procedural elements. Integrators and end users have developed proprietary libraries of reusable functions to standardize this functionality. Automation system vendors also provide their proprietary libraries to help make it even easier to assemble a batch control program leveraging the numerous “standard” pieces that have been developed throughout industry as part of the ISA-88 standard building process.
Despite these developments, an ISA-88 competent programmer is still required to properly assemble the library routines and define, in code, the relationships between the process cell components, such as vessels, units, equipment modules and control modules. Because of this requirement, once the relationships between entities of a model are hard-coded into a custom program for a customer, benefits of the model-based approach embodied in ISA-88—particularly agility—are lost.
With today’s powerful programmable automation controllers, it is finally possible to write and run—at a practical speed—the sophisticated software required to control a process cell based on a data-based model. The entire program can be reused, just like Excel can be installed on another computer, eliminating the need for a programmer who knows how to put together the parts.
Wizards in the software itself guide the model builder through the process of defining control modules, and then relating them physically via pipe paths and logically in equipment modules. For example: Do you need to alleviate water hammer in an equipment module? There’s a checkbox for that. Need to configure a valve to change positions every few seconds in a clean-in-place equipment module without affecting how it operates within a material transfer equipment module? Just access the checkbox for that and enter a time value into a field.
Experience, knowledge of standards, and best practices can be built into the software so that users don’t have to know anything about how water hammer is reduced or eliminated. They just have to check a box.
I believe that standards, best practices and our best experience do not have to remain in the hands of talented control system engineers. We can place those standards, best practices, and experience into the hands of a much wider group of practitioners who can join with us to bring greater benefit to manufacturing.
I have seen it work with ISA-88 and batch process control. I believe I will see it work with our other great standards in other industries.
Tim Matheny is president of ECS Solutions Inc., a certified member of the Control System Integrators Association (CSIA). He is also the author of a paper on the subject of model-based control, presented to the ISA Food and Pharmaceutical Industry Division in 2014. To obtain a copy of Tim’s paper, or for more information about ECS Solutions, visit their profile on the CSIA's Industrial Automation Exchange.
