Most faults in a control unit do not originate in the touch sensor. They start where the glass, electronics, front panel and testing are supplied by different vendors, and ultimately no one bears overall responsibility. This is precisely where complete HMI solutions come into play.
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Key points at a glance
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Anyone who assembles industrial control elements from individually purchased components optimises each component in isolation, thereby overlooking the most costly source of error: the interfaces between them.
The problem lies between the components, not within them
A capacitive sensor from Supplier A, printed glass from B, a front panel from C and the electronics from D may each be perfectly specified in their own right. Nevertheless, the overall system will not operate reliably if the touch IC is not precisely matched to this specific configuration, if the adhesive bond between the glass and the substrate is subjected to temperature fluctuations, or if the seal fails to maintain the required protection rating in the actual installation environment.
If a fault then occurs, the search for who is to blame begins. The sensor manufacturer points the finger at the electronics, the electronics at the mechanics, and the mechanics at the assembly. In practice, this lack of accountability costs more time and money than any single component. A single point of contact for the entire HMI solution closes precisely this gap.
Four technologies, one selection criterion: the operating environment
There is no single ‘best’ input technology. There is the one that is suitable for the specific environment. Making this decision at the outset rather than at the end saves on costly rectifications.
Capacitive solutions utilise precise PCAP sensors and a matched touch IC. They are suitable for industrial automation, control systems and medical technology. Smooth, printed glass surfaces are easy to clean and can withstand even demanding environments.
Resistive solutions have been superseded by capacitive ones in many areas, but they remain the preferred choice in harsh environments. Moisture, dust, dirt and operation whilst wearing thick gloves are all factors that favour resistive technology, for example in manufacturing, logistics or on construction sites.
Membrane keyboards are the cost-effective and flexible option. They can be custom-printed, backlit and fitted with tactile feedback, and combine well with front panels and printed circuit boards. In medical technology, vehicle manufacturing and the waste management sector, they stand out thanks to their robust, easy-to-clean surfaces.
Mechanical solutions prioritise robustness and a long service life. Aluminium reinforced with stainless steel ensures stability, whilst the under-anodised printing provides design freedom and protection against mechanical stress. In mechanical engineering and control technology, where tactile feedback is crucial, they remain the first choice.
Common mistakes when selecting complete HMI solutions
Based on practical experience, a number of recurring mistakes can be identified that make industrial control elements costly:
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The technology is chosen based on appearance or price, rather than the operating environment.
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The entire system is not tested, as each supplier only tests its own component.
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Protection ratings and seals are checked against the data sheet, not in the actual installation.
Each of these issues can be avoided if selection, integration and testing are all carried out by a single provider.
System reliability is achieved through integration and testing
A component tested in isolation says little about its behaviour in the finished control panel. Only a comprehensive product and functional test of the assembled system reveals whether the touch interface, electronics, mechanics and surface work together effectively. Optimally matched modules and a touch IC tailored to the application are the foundation for ensuring that an HMI operates reliably for years to come.
Frequently asked questions about complete HMI solutions
What are complete HMI solutions?
Complete HMI solutions are ready-to-use control units in which the touch screen, electronics, front panel and surface finish are all sourced from a single supplier, are optimally matched and are tested as a complete system. They eliminate the need to purchase individual components from multiple suppliers.
What are the advantages of a one-stop HMI solution?
The biggest advantage is end-to-end accountability. A single point of contact coordinates all components, tests the complete system and bridges the accountability gap that would otherwise arise between multiple suppliers in the event of a fault.
Which touch technology is suitable for which environment?
It depends on the application environment. Capacitive solutions are suitable for medical technology and industrial automation; resistive solutions are suitable for harsh environments involving moisture, dust or operation whilst wearing gloves; membrane keyboards are ideal for cost-effective mass production; and mechanical solutions are suitable for mechanical engineering applications requiring tactile feedback.
What are the common mistakes made when selecting industrial control elements?
Common mistakes include choosing based on appearance rather than the operating environment; considering cleanability and glove operation too late in the process; failing to test the entire system; and checking the protection rating and seals solely against the data sheet rather than in the actual installation.
Why is testing individual components not sufficient?
A tested individual component says little about the finished control panel. Only a full functional test of the assembled system reveals whether the touchscreen, electronics, mechanical components and surface interact reliably.
Conclusion
Complete HMI solutions are not a matter of convenience, but a risk assessment. End-to-end responsibility – from the choice of technology through to integration and testing – determines whether industrial control elements deliver in the field what they promise on the data sheet. Those who source all components from a single supplier purchase fewer interfaces and thus take on less risk.
Are you planning a new control system or looking to make an existing one more robust? Let’s discuss your operating environment and the appropriate technology, from the first prototype through to series production.
