To put it briefly, one could also call it user interfaces for interacting with specific pieces of equipment. More on that in a moment. The most familiar are the sort of interfaces with your home PC. These provide the user with a graphical interface for interaction – a GUI (graphical user interface), for example the desktop. The desktop metaphor helps us to interact with the programs and operating system.
In the case of HMI devices – which are frequently found in industrial areas, primarily in the fields of automation – the situation is different. In short, not only are the interfaces more varied than with desktop computers, so are the devices themselves. The interfaces range from very simple to more complex reading and control units. As an example, a light switch is a sort of HMI device. It recognizes two states – on/off – which are also optically represented and can also be changed. Of course, HMI devices can have any complexity. Display and operation must fulfill a wide variety of requirements. Any display size and quality of resolution, ease of integration, robustness and lifespan in constant operation are all demanded of HMI devices. Familiar examples of HMI devices can be found in the Siemens range of products: SIMATIC, etc. One particular class of equipment for which this is applicable would be Panel PCs. These HMI devices are used in so-called “smart factories” for the control, monitoring and optimization of the processes of machines and robots – that is, in the heart of automation and digitization.