Posted by: Harold Ennulat | December 6, 2010

Emerging HMI Standards

High Performing HMI’s

HMI’s (Human Machine Interfaces), also known as OI’s or OIT’s (for Operator Interface or Operator Interface Terminal) are typically PC based computers with displays that operators use in controlling and monitoring some kind of process or plant production operations. 

The ISA101, Human-Machine Interfaces committee has for some years now been working on coming up with recommendations that will help frame the HMI design. 

The areas currently being considered by the ISA101 committee are:

  • Clause 0: General
  • Clause 1: Scope
  • Clause 2: Normative References
  • Clause 3: Definition of Terms and Acronyms
  • Clause 4: HMI System Management
  • Clause 5: Human Factors/Ergonomics
  • Clause 6: Display Types
  • Clause 7: User Interaction
  • Clause 8: Performance
  • Clause 9: Documentation and Training

It is noteworthy that a formal HMI standard currently does not exist.  The ISA HMI standard is said to be 3 years out yet, and then it is unclear how specific it will be.

I ran across a text that appears to fill the gap till formal standards emerge.  The book is called “The High Performance HMI Handbook” by PAS.   After reviewing the overview and table of contents this book is on my leading list of resources to review before tackling my next HMI project.  Here is an excerpt from the overview:

High-Performance HMIs are designed to accomplish the following:

  • Provide optimal operator awareness of the state of the process
  • Make operators aware of key performance indicators and process trends
  • Enable immediate detection of abnormal conditions
  • Increase the success rate for handling abnormal situations
  • Decrease the time needed to complete mitigation tasks
  • Discourage reactive operation

The Seven Step Methodology to High-Performance HMI:

  1. Develop a High-Performance HMI philosophy and style guide
  2. Assess and benchmark existing graphics against the HMI Philosophy
  3. Determine specific performance and goal objectives for controlling the process during all modes of operation
  4. Perform task analysis to determine the control manipulations required to achieve the performance and goal objectives
  5. Design and build high-performance graphics using the design principles from the HMI philosophy and elements from the style guide
  6. Install, commission, and provide training on the new HMI
  7. Control, maintain, and periodically reassess the HMI performance

PAS is the company that supports the graying of the HMI screens so that color can be used to bring attention to abnormal situations or other conditions that requires an operator response.  Also emphasized in the handbook is the idea of working to turn data into actionable information.  A key way to do this is to use analog indicators that show the normal and recent range of motion of the process variable.  See the lead image in my previous post for an example of this.

This graying of the HMI is gaining momentum.  Rockwell and others are suggesting this as well as shown in my post on “Alarming Links & Resources“.

The idea of developing a written HMI philosophy is intriguing.  Documenting the purpose for an HMI application, what one might want it to do, defining how the HMI is to help the operator with situational awareness and readily actionable options during normal and abnormal situations, would appear to be useful.  The question comes up “how can this be justified”?  Typical projects do not have the time for this.  This handbook should make interesting reading.

It is also worth noting that some of the emerging HMI standards clearly appear to be driven by new alarming standards that have been recently introduced by the ANSI/ISA-18.2-2009 committee.

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Responses

  1. Opto22 has recently pubished an article reviewing the High Performing Practices as well as introducing why this might be important: https://twitter.com/HaroldEnnulat/status/459000191945699328


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