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Partnering March, 2021

Ensuring Reliable Performance through Proper HMI Design

By John Pannone, VP Sales — HMI Systems/Key Customer Management, North America, EAO Corp. F

rom a simple two-button in- strument panel to an exten- sive software/hardware-

based SCADA system at the heart of factory automation, proper human-machine interface (HMI) design requires integra- tion of the application, environ- ment, technology, and user er- gonomics. The best HMI designs combine intuitive, safe and reli- able performance with the specif- ic requirements of the user, cre- ating a lasting control solution.

Industry Standards Both general and industry-

specific HMI standards dictate

features, functional attributes and design elements. Even the placement of components, mark- ings and component colors can be influenced by regulations. It is a necessary first step to review in- dustry standards, including DIN/EN/ISO, EU Machinery Di- rective, UIC 612, SEMI S2-93, ANSI, IEEE, International Or- ganization for Standardization, and EMC requirements. Displays are a core element

of modern HMIs. Easy-to-read graphical information provides the ability to control multiple system functions from a single point or location. Common dis-

plays include LCD and LED non- touch displays for simple numer- ic displays or for applications in bright conditions. Touch displays can play a

critical role in functionality, but may depend on the operator and environmental conditions. Resis- tive touchscreens are generally used in industrial applications and can be activated by a variety of objects, including a finger or stylus. They are relatively inex- pensive and resistant to moisture, dust, oil, and cleaning agents, but vulnerable to damage from sharp objects. The second most frequently NEW GENERATION REFLOW

used type of touchscreens in in- dustrial applications are capaci- tive. This technology is popular for consumer products, due to its robust glass surface that protects it from scratches and chemicals. There are also surface acous -

tic wave (SAW) and projected ca- pacitive technology (PCT) dis- plays. Both offer image clarity and high resistance to surface contam- inants, liquids, scratches, and im- pacts.

Tactile control elements are

essential when operators do not have HMIs in their direct field of vision, such as critical control ac- tions found within lifting and moving applications. Combining touchscreens with tactile ele- ments makes it possible to over- come these disadvantages. Mixed technology solutions provide ben- efits that include intuitive opera- tion, discrete pushbuttons, illumi- nation, and soft keys.

Electromechanical Devices Electromechanical devices,

reflow soldering

vacuum soldering

temperature treatment

customized solutions

Machines for Thermal Processes from –50 °C up to +450 °C

such as pushbuttons, emergency stops, and others, will continue to be used in the future, due to their intuitive use, high degree of safe- ty, robustness, and reliability. Modern actuators are easy to

install, provide flexible communi- cations options, consume little power, and have a long service life of up to 10 million switching cy- cles. Stainless steel and special- purpose plastics are crucial for providing HMIs with chemical and UV radiation resistance. These devices should also be

modular and configurable to suit a variety of specific require- ments. Today’s mounting sys-

tems have a tight seal into which the actuator holder can be pushed or snapped in with only one hand and provide a secure attachment. In addition, functionality

By engaging an expert in HMI design, firms

can save costs and build reliable equipment, while meeting all necessary standards.

must not be affected by dust, water, oils, caustic solutions, and extreme environmental condi- tions. IP69K front protection is usually selected for harsh envi- ronments. Also available are short trav-

el technologies, which are cost ef- fective and include rubber keys in a typical keyboard, dome keys be- neath an overlay or a multilayer membrane. They offer HMI design flexibility and excellent haptic feedback. Trackballs, touchpads and joysticks should be considered when precise, intuitive movement and control are required.

Safe and Secure Safety and security devices

are straightforward and have lim- ited options but are critical to op- erator safety. Emergency stop switches are regulated strictly and must be actuated by a me- chanical action. The actuated state must be clearly visible, and the release must be performed manually. At this time, guidelines do not allow for a touch-based “certified” emergency stop system. Key-operated switches pre-

vent accidental or unauthorized access. Each key can provide au- thentication of employee groups or individuals and can even record operator access and time. HMIs are the link between

users and machines, regardless of their scale or size. As a result, understanding the requirements and accepted technologies of the market should come before se-

lecting an interface. Contact: EAO Corp., One

Parrott Drive, Shelton, CT 06484 % 203-951-4600 fax: 203-951-4601 E-mail: Web: r

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