Human-machine interfaces (HMIs) in evolution from operator terminals

IDEC Corp. HG2G-V5 5.7-in., HG3G-V8 8.4-in., HG3G-VA 10.4-in., and HG4G-VC 12.1-in. touchscreen HMIs are suitable for both new and retrofit applications.

HMIs and other operator interfaces and terminalsfunction as software and hardware access points between machineand personnel. In some cases, components called operator interfaceterminals or OITs (consisting of pushbuttons, LEDs, switches, andhard keypads and small and moderately customizable displays) haveyielded to HMIs. The latter in the context of factory and machineautomation today usually refers to full ruggedized touchscreenelectronics and memory loaded with operational recipes; advancedconnectivity options; signal and data processing capabilities; andthe ability to display relevant information and menus (even acrossmultiple screens) to human operators.

In fact, HMIs initially evolved from man-machine interfaces (MMIs) as well as graphical user interfaces (GUIs) into iterations accepting input beyond simple text — with the touchscreens just mentioned for image-based interfaces the world now takes for granted.

Even HMIs from a few years ago are being superseded by new HMI hardware and software systems capable of supporting IoT functionality — usually by letting operations make more use of plant and machine data (data handling) in increasingly automated operations as well as remote operations. Such HMI functions also include system real-time supervision, event logging and triggering, diagnostics, and enterpriselevel monitoring. HMI integration with any existing supervisory control and data acquisition (SCADA) and manufacturing execution systems (MES) is key here.

Where HMIs serve as a machine’s centralized controls, there is either connection to or integration of a PLC or motion controller. These controls serve to process axis feedback and I/O data for higher-level uses. Many HMIs today run real-time operating systems (OS); a few even include electronics with what’s called an asymmetric multi-processing (AMP) architecture. In contrast with common symmetric multiprocessing (SMP) architecture that runs a single OS across all CPU cores, AMP architecture lets the HMI run different OSs — usually as general-purpose logic on one CPU core and realtime controls on the other. That lets the control logic maintains real-time operations while HMI logic executes data collection, batch processing, and display tasks.

Today’s HMIs also aim to minimize the impact of operator mistakes and other inefficiencies. One approach is what HMI manufacturers call situational awareness — a machine-based capability to recognize problems or situations that are typical and atypical for the automated design.

Maple Systems Inc. in a strategic alliance with Weintek Labs Inc. serves the North American HMI market. Shown here is a Weintek cMT3090 HMI that extends accessibility to beyond that of typical products — because it supports remote access via smartphone and tablet applications. A built-in server lets the cMT3090 serve as a gateway between the plant and outside world.

HMIS SUPPORT PERSONNEL IN CHARGE OF MANY TASKS

Today’s machine operators handle an ever-increasing amount of data — and always more than any one person can process alone. Here, well-designed HMIs distill data to let machine operators respond quickly and efficiently to situations … and help keep them safe from harm. (In contrast, poorly designed HMI notifications can sometimes distract uninvolved plant personnel and slowly render involved personnel insensitive to the alarms — especially if the HMI throws an excessive number of warnings or irrelevant signals.) Where plant personnel isn’t parked next to a given piece of machinery all day, HMIs can also help communicate what would have once been observed by sound, feel, or sight.

In contrast with typical HMI applications of the past, which merely communicated machine status, today’s HMIs assist operators in understanding what’s normal for a given machine axis or sensor and what’s not. That lets even inexperienced personnel understand and effectively act upon system parameter values to address issues where needed. Where it’s appropriate that machine operators be fully informed and empowered, that can include communication through the HMI of potential consequences of ignoring the issue or addressing the issue with set actions.