Choosing HMI Data Entry Tools
Imagine, if you will, an operator on a plant floor monitoring a process...any process. The person is wearing a headset that includes a tiny display. An alarm sounds. The operator glances around, then speaks into the mouthpiece attached to the headset, verbally acknowledging the event and adjusting a setpoint.
AT A GLANCE
Traditional methods prevail
Touchscreens gain popularity
Enhancements hold promise
This article includes: Related reading on human-machine interfaces
Imagine, if you will, an operator on a plant floor monitoring a process…any process. The person is wearing a headset that includes a tiny display. An alarm sounds. The operator glances around, then speaks into the mouthpiece attached to the headset, verbally acknowledging the event and adjusting a setpoint.
Sound like a scene from Star Wars? Perhaps. However, wireless HMIs that are integral to the operator are feasible, and information could be entered into a system in just that way. Headsets exist with displays built right into them, projecting HMI screens directly onto the operator’s retina; systems respond to voice-activated commands. Although certainly not yet common—economic and durability hurdles remain—the technology is available today. ‘It’s a matter of pulling it all together and making it cost effective and suitable for an industrial environment,’ observes Roland Gendreau, product marketing consultant, Invensys/Foxboro.
In the meantime
Despite the technological realities of such a sci-fi scenario, more conventional data entry methods prevail, and undoubtedly will for the foreseeable future. However, enhancements to standard devices are definitely giving rise to data entry mechanisms with a more futuristic slant.
HMI data entry has traditionally meant changing set points and turning things on and off. However, as HMIs have become more sophisticated, do more, and are fed by higher-level systems, more is expected of and done through them. Picking a method or mechanism for data entry or system interaction is predominantly a function of application. Victor Verissimo, product manager, VersaView computer products (Rockwell Automation), views the selection process this way: ‘The primary driver for data entry mechanisms, and for understanding where which devices get used, is understanding the application requirements: How is this application different from something else in the plant?’
Factors such as accuracy, ruggedness, reliability, and speed also have an impact. And some industries are more likely than others to apply some types of data entry systems.
‘From a data entry or computer-based perspective, we’re still being asked to address traditional automation/visualization requirements,’ says Doug McEldowney, strategic marketing manager at Rockwell. ‘Basically, we need to present information to an operator or engineer in such a way that he is able to make a decision quicker, react to a situation faster, or interact with a process or machine in a more intuitive way. There are devices to facilitate that… HMIs.’
As a consulting engineer/system integrator, Frank Jacobs, project engineer, Perigon Engineering, looks at data entry from a different angle, yet sees it in the same light: ‘In our recent projects, we’ve seen a lot of the tried and true methods, especially bar code scanning. Keyboard and mouse is still a good way to enter data, but unfortunately this method is open to operator error. And keyboards also aren’t always durable. Those that are—sealed or encapsulated keyboards—often have poor tactile feedback, making them slower and less efficient to use.’
Touchscreens ‘R’ us
If keyboard and mouse are well within the comfort zone of the average HMI operator, touchscreens are not far behind and probably growing faster in popularity than any other HMI entry device. Screens are larger. The 6-in. grayscale screen common a few years ago has been replaced by a 15-in. color monitor. Prices have dropped significantly. And cleaner plant applications are paving the way for commercial touchscreen technology to make its way onto the plant floor. [The July issue of Control Engineering will include an article on touchscreen technologies.]
Why are touchscreens so popular? First, they are more intuitive than mouse and keyboard, providing a direct and natural way to interact with a system. The operator just points and selects, using a fingertip or a stylus. Many feature pop-up keyboards, allowing the operator to enter small amounts of information on the screen. Pop-up keyboards save valuable space.
There are disadvantages, however. Says Foxboro’s Gendreau: ‘Operators … have to do three major things: navigate through some kind of a display hierarchy; select the object to take action on; and manipulate the object in some way. Typically, those actions are taken with a mouse, keyboard, trackball, touchscreen, or all of the above. … Touchscreens are ubiquitous these days. But if the device is not properly defined, operator fatigue can be an issue. Typically, operators don’t enter much data, but if they do, doing so on a virtual keyboard can be awkward.’
Perigon’s Jacobs admits touchscreens are popular and useful, but also large. ‘You have to space things properly. In manufacturing plants, operators often have large hands. It is difficult to be accurate when using a touchscreen unless you are very careful or have sufficient space.
‘Touchscreens and virtual keyboards do work and they look nice, but I don’t believe they offer the best environment for operator data entry,’ he continues. ‘A lot of repetitive motion on a touchscreen can wear a hole in it. Then it doesn’t work anymore. They are expensive to replace. By comparison, a keyboard is cheap, but sometimes there just isn’t a place for a keyboard. So you end up with a virtual keyboard for text entry. Depending on the amount of text entry involved, you may be better off finding a different solution entirely.’
Kicking it up a notch
And there are other solutions. Bar code scanners , for example, are popular data entry mechanisms, especially as a means of identification. They are particularly common in materials handling and packaging applications, but almost every industry can use them.
Perigon’s Jacobs sees bar code scanners as playing a strong role now and in the future: ‘We’ve had a lot of success putting in bar code systems with hand held scanners. Symbol Technologies makes a bar code scanner with a PocketPC built right into it. You can develop applications using standard Windows-based technology for data entry right on the device. It is not excessively expensive; it is economically viable.’
Handheld, wireless devices extend and enhance the HMI data entry interface in a different way. With stylus and touchscreen in hand, operators take the HMI into the field. With these ink-enabled machines such as Microsoft’s TabletPCs running under the Windows .Net environment, data are entered as easily as writing.
Observes Renee Brandt, Invensys/Wonderware’s product marketing manager: ‘That’s simply how you get information into a TabletPC. For example, an operator may notice that a motor temperature is too high and want to draw the condition to someone else’s attention. In the past, he’d have to make a call to let someone know. With a TabletPC, he can make a screen capture of the graphics, then mark or highlight the image on the screen—circle the motor and write a note on it with the light pen. It can then be saved or emailed to the appropriate person for action. Such a system is really helpful for troubleshooting and sharing real-time information, and also for writing down thoughts about what has happened.
‘Such products let us write in information and the system recognizes what has been written. It will recognize a number, then change a parameter,’ she says. ‘Some devices even recognize foreign terms. An operator can change a process line from orange to grapefruit juice by writing it one the screen of a TabletPC in any of several languages—and the system knows what to do.’
Rockwell’s McEldowney agrees, but warns, ‘It is fairly accurate, but probably should not be relied on for critical application systems.’
Voice recognition systems also offer a way to enter information to an HMI, but reliability is not high. An operator may need to say something to a computer several times before the system understands. Notes Rockwell Automation’s Verissimo, ‘Voice recognition systems are definitely a type of data entry mechanism. There are systems available, but they need refinement.’
Authentication remains an issue. A system must be initialized to accept the voices it must recognize and the computer must identify an instruction as valid, adds Eric Dorgelo, platform strategy manager, Rockwell Software. ‘If anyone could walk up to a computer and tell it to do something, without providing identity information, there would be problems. Systems haven’t really reached the point of being able to filter one voice from another.’
Look into the LCD crystal ball
What of the future? Continued evolution of products to incorporate enhancements and increase efficiency is a safe bet. Notes Sriram Peruvemba, general manager, Three-Five Systems Inc., ‘Keyboards, buttons, and touchscreens are still popular data entry devices, but there’s a lot on the horizon. Although it is not yet as reliable or as robust as it needs to be, voice-activated input is coming. Flexible, small, mobile, and interactive are the operative parameters for future data entry.’
State-of-the-art for HMI data entry today is undoubtedly touchscreens, according to Rockwell’s Dorgelo. ‘We’ve definitely moved from keyboard and keypad membrane-based devices to systems that only use touchscreens. Components today are durable and accurate.’
Heightened touchscreen accuracy has been accompanied by other improvements, among them lower costs and slimmer designs. Says Foxboro’s Gendreau: ‘The move today to LCD touchscreens is part of a migration away from CRT-based interfaces that’s been accelerating as the price of touchscreens continues to come down. I estimate that, by the end of this year, you will see just about 100% LCDs across the market. And they offer many advantages. They take up much less space and are flexible to apply: a flat screen hanging off an ergonomic arm that can be installed almost anywhere. They use about a quarter of the power of a typical CRT, and they are more durable. They have a life expectancy 3 to 4 times that of a CRT. They also are neither susceptible to EMI, nor do they cause it. Price used to be a disadvantage, but costs have dropped markedly.’
Rockwell’s Verissimo calls the possibilities for data entry ‘almost limitless.’ He says: ‘The technologies that are available today to some degree can fulfill just about anybody’s fantasies for entering data into a system.’
Related reading on human-machine interfaces
Related reading from Control Engineering includes:
“Have HMI Will Travel”
“Tools for HMI Applications”
“How touchscreens work”