Buttons, Switches Still a Turn On

Even as Electronics Take Control of HMI Functions, There's Still a Need for Discrete, Standalone Devices

By Control Design Staff

As we've written in our recent Essentials of Machine HMI reporting, the foundational component of any machine automation solution is the human-machine interface (HMI). Local HMIs range widely in sophistication — and price — depending primarily on how much interaction and information exchange is required between the human operator and the machine itself.

SEE ALSO: Rugged Operator Interface Terminals: Build vs. Buy

A relatively simple, unconnected machine might need only a few hardwired lights and pushbuttons. At the other end of the spectrum, a fully functional industrially hardened PC could be required. In between these two extremes, we find a range of microprocessor-based operator panels or operator interface terminals (OITs) that provide a configurable graphical operator display and interface in a more compact, less expensive package than a typical industrial PC. In short, the need for increased application flexibility and the need to handle more complex information management tasks will typically drive the machine designer to more capable solutions.

In a recent Control Design audience study on HMI and related components, we learned that 65% of respondents indicated the operator interface hardware installed on their machines was a graphical display with touchscreen. That was followed by graphical display with keyboard or other input device (21%), then text-based display with integral input keys (4%), and discrete panel switches and lights only (1%).

For all but the simplest of applications, increased functional and performance requirements drive machine OEMs away from simple status indicator lights and toward increasingly sophisticated HMIs equipped with graphical displays. On the human input side, with the exception of a few critical buttons (for emergency machine shutdown, for example) discrete switches, too, give way to configurable input keys which, in turn, are yielding to integrated touchscreens.

Nevertheless, on many levels, there's a need for discrete input devices, as this roundup demonstrates.

CD1308R OMRON Less Is More  
A3U 22 mm, flat-surface, pushbutton switches have a ribbon-cable connector for less assembly, less wiring and less chance of errors. 50 mm body length reduces board height to save space under a panel. There are lighted and non-lighted pushbutton versions with a range of pushbutton colors.
Omron Automation and Safety
CD1308R IDEC Sweet Little 16   
LB series of 16 mm miniature switches include illuminated selectors, lever selectors, dome pilot lights, lever switches and buzzer models. Illuminated selectors and dome pilot lights are available in green, red, white, amber, yellow and blue. The switches have a 5 A operating current and are available with a choice of SPDT, DPDT and 3PDT contact. All provide an IP65 degree of protection.

Turn to Safety   
Mushroom head industrial switches are available with a 30, 40 or 60 mm operator heads. The e-stop switches include turn key to release, turn to release, and pull to release. The actuator structure is suitable to warrant direct opening operation with mechanical latching for emergency stopping per ISO 13850 and IEC/EN 60947-5-5. Up to six contacts can be added, and the green line around actuator body indicates when the emergency stop is activated or at rest.

CD1308R OMEGA Installation a Snap   
OMPBD7 22-mm pilot devices offer modular assembly and interchangeability. A toolless mounting latch mates the front element with the contact blocks and other back-of-panel components. The mounting latch is available in a plastic and metal design. The latches install with a click and are removed by pushing a rotating collar to the right.
Omega Engineering
CD1308R BANNER Flat Stop   
40-mm emergency stop buttons mount to flat surfaces without disassembling or individual wiring. They come with a non-illuminated base in four styles: standard, illuminated actuator; lockable actuator and an illuminated lockable actuator; or in an illuminated base with a standard or a lockable actuator. Push-to-stop, twist-to-release or pull-to-release actuator and direct (positive) opening operation is compliant with ANSI B11.19, ANSI NFPA79, ISO 13850 and IEC/EN 60204-1.
Banner Engineering
CD1308R WAGO Rock On, Rock Off   
789 Series DIN-rail mount switch modules are 17.5 mm wide with rocker switches. 789-800 provides automatic and hand modes to switch a device/machine between PLC-driven operation and manual mode for troubleshooting, etc. 789-801 on/off rocker switch lets users manually control typical accessories within a control cabinet.
CD1308R ELECTRO See More Lights   
SW44895 quad lamp, pushbutton SPST to DPDT switch assembly options include rubber dust boot for panel protection and enlarged lens cap to match industry standard sizes. Performance specifications include life capability of 100,000 minimum actuations. Ratings are 2.0 A resistive, 0.5 A inductive.
Electro-Mech Components

Without a Wire   
Limitless wireless operator interface (WOI) is a packaged pushbutton controller with both momentary and maintained contact options. Users choose and install a desired operator (22 mm rotary switch, key switch, key) or a pushbutton. It uses license-free RF wireless 802.15.4 WPAN protocol that provides up to a 1,000 ft line-of-sight communication range.
Honeywell Sensing and Control


Switches and More   
Otto Series switches include toggle, rocker, Hall Effect and pushbutton switches, switch guards, grips and accessories. Value-added switch assembly services such as switch harnesses, switch panels, and engraving and hot stamping of legends are available.
Peerless Electronics

CD1308R AD See the Buzz   
With polycarbonate/ABS housings, 22.5-mm panel-mount continuous-tone, electrical buzzers have LED indicators with red or yellow lenses. Two-wire, high-intensity LED 29-mm diameter beacons are available in panel-mount styles, or on a M20 threaded base for use with limit and cable-operated switches.
CD1308R PATLITE Light ‘em Up   
LP6US LED surface-mount lights in blue, red, yellow and clear have six LEDs with 33 flash patterns for use in environments -40 to 149 °F. Up to four lights can be synchronized to form a larger warning system. These lights are rated for 10-30 Vdc operation, and are CA Title 13 compliant and SAE J595 certified.

You Light Up My Panel
Multi-voltage pilot light modules in 16, 22 and 30 mm sizes support 20–240 Vac/Vdc. Low-energy-consumption LED lamps with Lexan lenses in six colors last 100,000 hours. The modules are Type 4/4X rated.

CD1308R WEIDMULLER Marks the Spot   
MetalliCard metal markers labeling system provides an in-house print capability on aluminum or stainless-steel marker plates for pushbutton and control panel identification. Installation options include self-adhesive, riveted markers, attached with plate holders. Pushbutton holders work with 22 mm pushbuttons from various manufacturers.
CD1308R ALTECH Your Choice
Preassembled and ready to install or assembled-to-order control stations include a heavy-duty, cast aluminum enclosure that's assembled with 22 or 30 mm pushbuttons. Use up to two contact blocks with the illuminated operators or up to four contact blocks with the non-illuminated operators. This enclosure can be modified to accept any non-illuminated 30 mm operator or pilot light as well.
CD1308R EATON C the Light   
C22 pushbutton family has operator and contact blocks together in one housing. The 22-mm design provides the same pressable area as 30 mm buttons. It includes LED illuminated pushbuttons and pilot lights, twist-to-release emergency stops, selector switches, and comes in flat and extended non-illuminated versions.
CD1308R CandK Remotely Safe   
E-Box low-profile housing for single control components at detached or remote locations includes bottom and top parts, contact module with contact block, and an e-stop actuator. Choose gold contacts for 35 V, and 100 mA maximum or silver for 250 V and 4 A maximum, which is available with two normally closed contacts, or one normally closed and one normally open.
C&K Components
CD11308R RAFI Slim Automation   
RafiX 22 FS+ products include illuminable pushbuttons with a protruding or flat baffle, selection/key/mushroom-type pushbutton switches, and e-stop buttons, signal indicators, potentiometer actuators and USB feedthrough. All actuation products have IP65 or higher rating.
CD1308R PFANNEN Attention Getter   
Signaling solutions for machinery control panels include Series P22D LED pilot light, choice of continuous On or 1 Hz blinking. It installs in standard 22.5-mm cutouts, and has a width of 1.1 in. outside diameter. Lens colors include white, amber, red, blue, green, in voltages of 12, 24, 115 or 230 Vac/dc.