Defining (and re-defining) HMIs
From a simple device for viewing an activity to a complex, sophisticated tool for monitoring, controlling, and analyzing processes and systems, the human-machine interface (HMI) has grown—and grown up. Even its name has changed. From man-machine interface to graphical user interface to operator interface, the terminology has evolved, but the acronym HMI is seemingly universally accepted.
Click on the company links in the article to read the complete comments from each participant.
From a simple device for viewing an activity to a complex, sophisticated tool for monitoring, controlling, and analyzing processes and systems, the human-machine interface (HMI) has grown—and grown up. Even its name has changed. From man-machine interface to graphical user interface to operator interface, the terminology has evolved, but the acronym HMI is seemingly universally accepted. But just what is an HMI?
We asked end-users and manufacturers and, not surprisingly, found that definitions abound. What we learned is summarized here.
'At the heart of the human-machine interface is the information display ,' says Dale H. Maunu, director, business development and procurement, Optrex America . Gricha Raether, distributed I/O and process control product manager, National Instruments , observes, 'Human-machine interfaces are typically a piece of graphical software used to monitor, visualize, control, and change a specific process or machine.' Phoenix Contact's push buttons and indicator lights with color touchscreens ,' while Jim Elwell, president of QSI Corp ., defines HMIs 'by physical form, type of equipment with which the HMI is to be used, sophistication, and cost.'
Beyond the screen
While definition varies with interests, there is near universal agreement that HMIs are growing ever more sophisticated, and connectivity is dramatically extending their influence. Says Microsoft 's Ron Sielinski, senior industry technical strategist, manufacturing industry unit: the HMI used to be 'the operator's window into the manufacturing process, a replacement for switches, pushbuttons, and indicator lights.' Now, it is 'a window into all of manufacturing operations, an interface that unifies all the information an operator needs into a single view.'
Roy Kok, director of HMI/SCADA product marketing, GE Fanuc Automation , has a similar outlook: HMIs are no longer just local interfaces. Web technologies enable browser-based viewing for remote operation and diagnostics, he says. 'HMIs are no longer islands of information. They fit into frameworks of automation technology, integrating with historians, higher-level reporting and analytical tools, and real-time information portals.'
Computing power that can be dedicated to an HMI has increased tremendously, says Annemarie Diepenbroek, HMI product marketing manager, Honeywell Process Solutions. Today's HMI, she says, breaks down barriers; functions as well during abnormal situations as during normal situations; makes decisions simpler; empowers employees; continuously monitors the health of all plant assets; and is secure.'
HMIs have evolved from stand-alone computer nodes to complete visualization and control systems,' says Renee Brandt, Wonderware product marketing manager for visualization products. 'The mobility, flexibility, and security of HMI systems has evolved to enable companies to see information from anywhere at anytime.'
No matter how advanced the technology, its optimization depends on the actions of the operator or engineer. Properly linking the human to the process is imperative, stresses Samuel M. Herb, PE , Consultant. 'Any device between the two must talk, in each direction, and in a way that is unambiguously understood by the other. Each time a change in technology permits a new and different way (even just by a little bit), we humans must go through a learning curve on how to best use that technology.'
Three-Five Systems' Sriram Peruvemba also emphasizes the human role, calling HMIs liaisons between human operators and machine controls. 'They translate human intentions for a certain machine activity into commands to which the machine is programmed to respond,' he says. Then, 'feedback signals from the machine are translated into audible or visual output that a human can comprehend.'
Coming to complete agreement on such a dynamic technology is obviously difficult. HMIs today are unquestionably complex systems that reach across the enterprise. Also unquestionable is that the definitions we construct today will change tomorrow. Predicts Three-Five's Peruvemba: 'Tomorrow we will have haptic controls, voice input, and wireless displays that will create a paradigm shift in the way we perceive HMI devices.' [Haptic controls apply tactile sensation to human/computer interaction.]
And once again we will need to define—or re-define—HMIs.