What is the best way for our customer’s techs to interact with our machines via handheld devices: Should we be using touchscreens, self-contained keyboards, pointing devices or a combination of all of them? What are the pluses and minuses of each approach?
—from February ’08 Control Design
Touch or Type?
Our customers today are leveraging the full range of operator interface technologies. It’s not uncommon to find touchscreen terminals in one location of a customer’s facility and industrial mice/keyboards in others. It really boils down to a couple of contributing factors.
For applications that require significant operator input, particularly those that require updates containing both alpha and numeric data, industrial keyboards and bezel-mounted keypads are very common. If the operator provides go/no go inputs or machine/process set point information, then touchscreens are more popular.
Environmental considerations also must be taken into account. A bezel-mounted keypad or industrial mouse/keyboard is much more common in a resistance-weld application area, where weld splatter and dust could interfere with the long-term operability of a typical touchscreen.
Paul Vondrak, product marketing manager,
Rockwell Automation
Touchscreen Keyboards
The optimum interface for a technician in the field has several considerations.
- Is the user comfortable with common computer?
- Is the environment harsh, including extremes of temperature, moisture, dust or other factors?
- Does the user wear gloves?
- Is space limited?
- What does the software application look like? Does it cater to a touchscreen?
A touchscreen is a great, user-friendly interface and often comes standard on handhelds as well as fixed-mount industrial computers with 15-in. displays.
Touchscreens come with resistive or capacitive technologies. Both are good for millions of touches and the user’s finger simply replaces the standard mouse. A double-tap on the screen emulates a double-click of a mouse. Capacitive touch is more durable than resistive but a user can’t use a gloved hand. Resistive is much more common and thus less expensive to deploy.
It is important to give the user large touchscreen targets with a feedback function. If the application has small targets or scroll bars, touch can be frustrating, especially if the user is wearing gloves.
A pop-up, virtual keyboard can be used with the touchscreen. Pop-up keyboards can be customized to your specific application and can be hidden in the task bar when not in use.
If an external keyboard is required, then a rugged version is best-suited to harsh industrial environments. Rugged, sealed keyboards, with optional backlighting are available in numerous form factors. Small units with alpha-only to large extended keyboards with function buttons and numeric pads accommodate most any data input need. Rugged, sealed keyboards sold into data collections and public safety applications are expensive but designed to last for three to five years.
All external keyboards have optional pointing devices. These are ideal when the movement of a cursor is an inherent part of the user’s daily work. The pointing devices are located on the center of the keyboard and appear as either scratch pads or hula points and retain the sealed characteristics of the keyboard.
John Geary, vice president,
Glacier Computer
Simple Begets Simple
In general, the simpler the interaction, the less sophisticated the device required.
If simple, set point entry is required, stationary keyboards are adequate, but they are so limited in what they can do that they rarely are used anymore.
The overwhelming preferred method today is to use a touchscreen.
There are many different ways one can configure the touchscreen to provide the most effective method to interact. Further, with the advancement of wireless technology one can select between a stationary panel mounted on the machine or close to it in a control cabinet, or a completely wireless mobile panel. Wireless mobile panels provide all the flexibility as stationary touchscreens but with no wires.
Both stationary and mobile touch panels provide a very effective, cost-efficient way for service technicians to interact with machines.
Harold Muma, product marketing manager
HMI, Siemens E & A
June's Problem
We need TO add hydraulics to a newly designed module in our machine line, to move heavy loads relatively quickly and with precision. Can we control hydraulic pumps and actuators with the same standard PLC that we use for other machine control functions, or do we need to look into more specialized hydraulic controllers?
SEND US YOUR COMMENTS, SUGGESTIONS OR SOLUTIONS FOR THIS PROBLEM. We’ll include it in the June ’08 issue, and post it on ControlDesign.com. Send visuals if you’d like—a sketch is fine. E-mail us at [email protected]. Please include your company, location and title in the response.
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