Building Better SCADA/HMI Applications: Understanding Your Hierarchy of Information

When developing interfaces for anything from complex SCADA systems to remote HMIs on smartphones and tablets, the way information is arranged and displayed with play a large role in the effectiveness of your application for both machine operators and decision makers. When you have the luxury of building SCADA/HMI applications from scratch, a solid understanding of what data is most important and why will help you create an interface that is both easy to read and invites engagement.

Take, for example, an application that requires you to navigate through several screens to get information you need, see alarms, or respond to potential issues. Compare it with one that displays key metrics front and center and allows operators to interact with their data without excessive use of menus or clicking. Which do you think will offer a smoother experience?

The principles of the Hierarchy of Information

Good design can incorporate color, sound, visual displays, or text. How they are used will determine how effective the user experience is. Good design considers the user at every step and tries to create an intuitive experience that will allow nearly anyone to navigate and access the information based on universal communication tools. Poor design often includes the same information but makes it difficult or confusing to access and understand.

The difference between a good HMI and a bad one can be as simple as an application that understands what is most important to the user, and one that doesn’t.

Here are some tips that might help you determine the hierarchy of information for your particular application:

  • First, know what the application is first and foremost meant to do. If it’s meant to monitor a single machine, then clear performance metrics with context should be visible at all times. If the key focus is uptime, then the information most readily accessible should reflect any potential issues that might cause the machine to stop.
  • Once the primary focus is determined, set an order of importance for other necessary functions. For example, alarms, trends, connectivity status, etc. The information should always follow this hierarchy consistently throughout the application.
  • All information is important, but not all information requires quick reactions. Ensure that information that does not need to be accessed all the time does not compete for the attention of the operator.
  • Also ensure that competing issues are arranged so that the operator clearly knows which are a priority. If three alarms go off at once, the user should clearly understand which order they should respond in. Alarms should also be set up in such a way that there is no incentive or need to ignore them. Ideally, the information displayed should warn an operator of possible issues before an alarm is ever necessary.
  • All information should have context. It does no good to know that a tank is at a certain pressure if the operator does not understand what pressure is ideal, and how much variation is acceptable. All information displayed should allow the operator to understand if they are trending in negative directions or efficiency is declining. That will allow them to work pro-actively to prevent issues before they ever occur.

Because there are no hard and fast rules for good design, it is important to test your interface with multiple people, preferably from very different backgrounds. If one subset of people finds your system intuitive and another doesn’t, then look for ways to streamline the application so that it is accessible for everyone. This may be as simple as including multiple language options, or designs that accommodate users with color blindness.

AVEVA Edge has all the features and functionality you need to make an HMI or SCADA system that effectively communicates information in a timely way and allows you to make real-time decisions.

See the AVEVA Edge page for an online demo and free trial download


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