Multi-touch operation, already familiar to users of smartphones and tablet computers, is coming to industrial HMIs and panel PCs, promising easier, more intuitive and faster operation, as well enhanced safety. At the recent SPS/IPC/Drives exhibition in Germany, several suppliers were showing products with multi-touch capabilities.

B&R Automation, for example, was demonstrating the multi-touch capabilities of a high-definition 21.5-inch Automation Panel and suggesting that multi-touch could “bring about a revolution in ergonomics for machine and system visualisation”.

Multi-touch screens can detect the presence of two or more points of contact – hands or fingertips – simultaneously. This allows users to perform functions such as zooming, scrolling, swiping, turning objects and “flicking”. These functions make it easy to move through lists and documents, to change screen views, and to enlarge or reduce displays.

It is also possible to define touch “gestures” which trigger predefined actions. The HMI/Scada developer Copa-Data suggests, for example, making tick gestures on a screen to acknowledge alarms, or drawing S shapes to return to the start screen.

Copa-Data has implemented multi-touch in its zenon software (above), allowing users to replace menus by “docks” – toolbars that provide project symbols allowing rapid access to important screens or applications. The symbols can be re-arranged in the dock using multi-touch drag-and drop functions.

Another potential use for multi-touch is safety. For example, by adding an extra on-screen button, safety-critical actions can be executed only if the screen is touched using two hands. Two-handed operation can also ensure that accidental screen touches do not result in unwanted operations or changes in parameters. Multi-touch can also simplify log-in procedures by using personalised screen gestures to authenticate users.

Although B&R does not expect two-handed operations to replace dead-man’s controls “just yet”, it says that they can prevent critical steps from being activated unintentionally.

Also at SPS, Beckhoff was showing a range of multi-touch displays (above) using a “projective capacitive” touchscreen technology that allows “flowing” touch operations operations in tiny steps, without any jerking. The technology supports two-hand or five-finger operation, even if the operator is wearing latex gloves. A special controller prevents accidental operation by, for example, a drop of water or the palm of a hand.

“Touchscreens are not likely to replace devices with physical keys completely,” says Raimund Ruf, manager of B&R’s HMI business, ”but they will continue to advance into more and more areas due to their versatility”.