Reviewing ANSI/ISA-101.01 HMI standard for process automation

Mike Lennon, P.E.

Lennon points to example of Level 3 HMI graphic

Michael A. Lennon, P.E., Operations Manager at Applied Control Engineering, presented an informative talk on upgrading HMI screens. He covered tackling upgrades of existing systems as well as new projects. The meeting, held at Rumsey in Conshohocken on January 18th, attracted about 20 attendees. Mike noted that his presentation overviews recommendations of ANSI/ISA-101.01 Human Machine Interfaces for Process Automation Systems, a standard published in 2015.

Mike said that when upgrading an existing system, often the current HMI:

o follows the P&ID graphic
o has no common guide for style
o assigns colors inconsistently
o shows no indications of trends to provide context.

Despite these shortcomings, management and operators may resist dramatic changes. The best approach is to implement change incrementally, concentrating on what works, colors, and navigation. It’s important to include input and buy-in by operators.

Mike said that the standard recommends primarily a gray screen where bright colors attract attention only to developing process problems. A bar of buttons at the bottom of the screen can be used to navigate to a new screen with details of an alarm condition. Graphics to avoid include gratuitous animation such as spinning motors, moving conveyors, and splashing liquids.

For a new project where the design of the HMI starts from scratch, the standard documents a four-level approach:
o Level 1: Overview of project
o Level 2: Primary operating display
o Level 3: System/Subsystem detail displays
o  Level 4: Diagnostic displays

Initial meetings can concentrate on such topics as color conventions, navigation philosophy, and use of contextual information (trends). Mike said it’s best to involve multiple system people, such as engineers, supervisors, and operators. The P&ID can form the basis of the Level 3 detail displays. These can lead to development of the Level 2 display that eliminates unimportant detail and provides a good overview of a system’s state.

Level 2 HMI screen

Example of Level 2 HMI screen that eliminates unimportant detail

Mike concluded his presentation with a slide of additional references for becoming familiar with good HMI concepts. An interactive Q&A session followed his talk. To download Mike’s PowerPoint click here.


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