How to Select the Ideal HMI for your Application?

The relationship between humans and machines is evolving rapidly, reshaping how organisations operate, innovate and compete. As Industry 4.0 matures, many manufacturers are beginning to embrace the principles of Industry 5.0, which combine advanced technologies with human creativity, sustainability and resilience. To realise this vision, organisations must continue their digital transformation by building smarter factories powered by automation, IoT, AI, connected data and intelligent production systems.

Along with industrial progression, visualisation systems need to provide more efficient ways of interaction on a machine-operator level. These next-generation human-machine interfaces (HMIs) provide manufacturers with an opportunity to differentiate themselves by implementing smarter, more connected automation solutions that support digital transformation.

What is an HMI?

Human-Machine Interfaces are often used in industrial manufacturing and systems. They are necessary for controlling and signalling automation devices. Human-machine interface products help operators control machinery and optimise efficiency by providing information about progress and mechanical performance. Basic HMIs with LED indicators and more complex ones with touchscreens and additional features are available on the market.

Touchscreen HMIs for industrial automation are an established technology that give value to many machine and process automation applications by expanding the capabilities of switches, buttons, and lights in a control panel. The touchscreens are based on components, such as touch controllers and software drivers. Their common control features allow the system to react when a particular surface is touched. The touch sensor is the touch-sensitive surface. They can be operated by fingers and keyboards or mouses.

When reviewing HMIs, it is important to know:

• Integrated requirements and various connection options for controllers.
• Configuration of HMI applications.
• Implementation of individual hardware and software requirements.
• Industry-specific certifications and approvals.
• Operator panels in various sizes and performance classes
• Use of various materials and touch technologies.
• Implementation of customer-specific design adaptations.

Selection guide for HMI devices

Depending on many factors, including display resolution, number of drivers used in parallel, memory required for the visualisation project, number of connected controllers, number of logs, HMIs might differ. Have a look at some of the considerations for selecting one below:

Display size & resolution

Often, the resolution of the display can be problematic. Operators wonder if the panel should have a small or big screen size and what is the best resolution required to show the graphic object details correctly. The operator should thoroughly assess each use case for an HMI to ensure that the right solutions are chosen based on the application requirements.

More extensive displays provide programmers with better space to work with when creating graphics. Most users would want as big a display size as possible, particularly if they need to choose touch links, but also if the application is view-only and they wish to monitor the display from a distance.

Recommended display resolution for these panels are:

• Basic applications: with VGA (640 x 480 pixels)
• Standard applications: with SVGA (800 x 600 pixels)
• High-end applications: with SXGA (1280 x 1024 pixels)

System communication

The system connectivity usually requires an Ethernet port so the HMI can communicate on the PLC network. The number of drivers that are possible to use in parallel is one Ethernet for basic applications, 1 plus OPC communication in standard applications and 2 plus OPC communication in high-end applications. The number of PLCs per driver is 1 to 5 and 1 to 10 for connected at the same time PLCs.

Memory requirement

It is critical to ensure that the CPU and memory capacities of a system are sufficient to control it. Expandable memory or different memory sizes in HMIs may eliminate some limitations. Advanced features like on-board computations, trends, and recipes will have an impact on HMI performance, thus it's recommended to utilise cautious estimates.

According to Phoenix Contact guidelines, the memory required for visualisation for basic applications usually differs between 16 and 32 objects per page, with space for animated objects (usually one per page). In standard applications, the number of pages increases to 64 with the opportunity for 128 objects per page, with a maximum of 32 scalable objects and 5 animated objects per page. However, high-end applications allow for 256 pages, 512 objects, 64 scalable objects, and 5 animated objects.

Data applications become easier now with HMI's support, where users can install their removable storage for data logging on HMIs with one or more SD Card slots.

Users & Logs

In the topic of user management, depending on the application (basic, standard, high-end), the number of users varies between 16 to 512 and up to 1024, also allowing for user groups (up to 64). On the other hand, logging allows for 4 to 16 number pens with a maximum number of data loggers per project in standard and high-end applications between 16 to 32.

What to consider when choosing HMI for your project?

HMIs can be simply put in two main categories. There are basic HMIs and wireless networked HMIs. To choose the correct one, whether it is a central control room, in production or visualisation directly on the machine, we present different brands to make choosing an HMI solution easier.