You would think that if you plan to pay someone to sit in front of a screen (or a bunch of screens) all day every day, you would want those screens to be as effective and performance-oriented as possible. You would think that every possible effort would be employed to ensure that this employee was given all of tools available to assist him/her in performing his/her assigned duties. That’s what you would think.
Unfortunately, for many process control operators and technicians, this is not the case at all. They are relegated to using screens designed 20 years ago or more, using outdated graphics and without any concept of the HMI design best practices that have been developed over the last couple of decades.
You would think that the research on industrial accidents that has pointed unequivocally to poor HMI screen design as a primary contributing factor in process failures that have cost millions of dollars – even killed several people – would lead our captains of industry to recognize the hidden cost in employing outdated screens. You would think all kinds of things that are apparently not true if thinking is something that you’re into.
So, why is nobody upgrading their HMI displays? Money. The cost is too much when people are of the belief that what they have works just fine. The problem is that it is not easy to quantify the cost of what could be, and so people are left with just the cost of what is. And, frankly, what is isn’t good enough.
What makes a good HMI screen? There are different schools of thought on that, but there are some factors that most agree are necessary in a high performance display:
- Clarity – Graphics are easy to read and clearly show the process state and conditions. Graphics will display relevant information and not just data. Alarms and indicators of abnormal conditions are clear and prominent.
- Consistency – Graphics are standardized and consistently formatted. Interaction requires a minimum of keystrokes or pointer manipulations. Navigation is arranged in a logical, heirarchical manner.
- Feedback – Controls will function consistently in all situations. Important actions have confirmation mechanisms to prevent inadvertent activation. Design principles are employed to reduce user fatigue.
Of course, much more can be said on the subject, and much more has been written. There are numerous best practices and techniques that can be used to ensure your HMI screens are efficient and performance-oriented. Too few of them are.
It is a researched and verified fact that an improved HMI means fewer accidents, less downtime, less human error, greater efficiency, and greater anticipation and control of abnormal conditions.
The next time you consider how much it would cost to upgrade your HMI displays, do yourself a favor and consider how much not doing it is already costing you.