Choose the right HMI for your application

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In the near future, the communication between humans and machines will change, which will trigger a new industrial revolution. The development of Industry 4.0 will give way to Industry 5.0. But before companies can fully commit to this transformation, they must focus on transforming their businesses into smart factories through automated manufacturing, IoT, smart data, AI and new technologies.

As the industry advances, visualization systems must provide more efficient ways to interact at the machine and operator level. The new generation of human-machine interfaces offers every manufacturing plant a unique opportunity to differentiate itself from the rest of the market by implementing the right solution and entering the real world of digitization in terms of exploiting the Automation system HMI.

What is an HMI?

Human-machine interfaces (HMIs) are often used in production and industrial systems. They allow the control and signaling of automation equipment. With information on work progress and mechanical parameters, human-machine interfaces help operators control machines and optimize their performance. Besides basic HMIs with LED indicators, more complex HMIs with touch screens with additional functions are also available in the market.

Touch HMIs used in industrial automation are a widely used technology that adds value to many machine and process automation applications by extending the capabilities of the control panel switches, buttons and controls. Touch screens use components such as touch controllers and software drivers. Common control features of touchscreens allow the system to react when a particular surface is touched. The touch sensor is the touch-sensitive surface. Touchscreens can be operated with fingers and a keyboard or mouse.

When choosing an HMI, the following points should be considered:

  • Integration conditions and different options for connecting controllers.
  • Configuration of HMI applications.
  • Implementation of individual hardware and software requirements.
  • Certificates and approvals required by the industry.
  • Different sizes and performance classes of control panels.
  • Use of different materials and tactile technologies.
  • Implementation of custom design solutions.

Choose an HMI device

HMIs can differ in many parameters such as display resolution, number of drivers used in parallel, memory required for visualization, number of commands connected, number of registers. Advice on HMI devices is described in the Phoenix Contact selection guide, some of which are detailed below:

1. Screen size and resolution

Often the screen resolution can be an issue. Users often hesitate between large and small screens and wonder which resolution will be the best to display all the details. When choosing a screen, consider the specific needs of the application.

Larger screens give developers more workspace when creating graphics. Users tend to prefer screens that are as large as possible, especially if they are going to use the screen in a touch-sensitive manner, but also when the application is purely for reference and they intend to monitor the screen at distance.

The recommended display resolution for this type of panel is:

  • Basic applications: with VGA (640 x 480 pixels)
  • Standard applications: with SVGA (800 x 600 pixels)
  • Advanced applications: SXGA (1280 × 1024 pixels)

2. System Communication

System connectivity typically requires an Ethernet port through which the HMI can communicate with the PLC network. Phoenix Contact HMIs have a polling rate of 250 ms to 1000 ms. The number of drivers that can be used in parallel is 1 x Ethernet for basic applications, 1 in addition to OPC communication for standard applications and 2 in addition to OPC communication for advanced applications. The number of PLCs per driver is 1 to 5 and 1 to 10 for connected at the same time PLCs.

3. Memory requirements

Ensuring sufficient CPU and memory performance to support the system is essential. The ability to expand memory or use different memory sizes in HMIs can eliminate some of these limitations. Advanced functions such as built-in calculations, trends, and formulas will affect the performance of the HMI, so their estimation should be approached with caution.

As recommended by Phoenix Contact, the memory required for visualization in basic applications is typically between 16 and 32 objects per page, with space for animated objects (typically one per page). In standard applications, the number of pages increases to 64 with a possibility of 128 objects per page, with a maximum of 32 scalable objects and 5 animated objects per page. Advanced applications, on the other hand, can benefit from 256 pages, 512 objects, 64 scalable objects and 5 animated objects.

HMI support now facilitates data processing applications as users can install removable storage for saving data to HMIs with one or more SD card slots.

4. Users and Registries

The number of users depends on the sophistication of the application: basic applications support 16 users, standard applications 512, and more advanced applications up to 1024. It is also possible to create up to 64 user groups. users. The data logging function, on the other hand, allows 4 to 16 connections with a maximum number of loggers per project in standard and advanced applications from 16 to 32.

What should be considered when choosing an HMI?

HMIs can be divided into two main categories: basic HMI and wireless network HMI. Here are some HMI solutions for use in central control rooms, production facilities and for visualization directly on machines.

1. Phoenix Contact

According to Phoenix Contact, reducing automation costs requires effective monitoring and data capture. The functions of HMIs from Phoenix Contact depend on the application category – they can be direct, high-performance and multi-functional applications. Phoenix Contact’s wide range of HMIs includes solutions for many hardware and software needs.

The advantages offered by Phoenix Contact are:

  • Custom solutions.
  • Easy to use with pre-configured and pre-installed hardware and software.
  • Easy scalability.
  • Part of a complete linear system with HMI interfaces.
  • The same software version for all versions and capacities.
  • Aluminum front for durability and strength.
  • Flexible connection of controllers.
  • Internet connection and efficient operation in multi-user mode.
Touch screen 9″ 800 x 480 IP65 Ethernet/USB/SD card, Phoenix Contact
Touch screen 9″ 800 x 480 IP65 Ethernet/USB/SD card, Phoenix Contact


Siemens specializes in second-generation operating and monitoring devices. The visualization devices offered by Siemens improve process quality in compact plants or smaller applications. The 2nd generation SIMATIC HMI Basic displays offer new control and monitoring possibilities, especially for mechanical engineers.
Besides screen quality and size, the 2nd generation Basic displays offer many innovative features such as recipe management, alarm recording, trend function and language change. The innovative user interface provides access to a wide range of functions and is made more user-friendly with new controls and graphics.

The main characteristics of the 2nd generation Basic Panels HMI:

  • Ideal for simple HMI applications.
  • Designed in the TIA Portal.
  • Mounting compatibility with SIMATIC HMI Comfort panels.
  • Flexible scalability in terms of HMI.
  • High resolution large screens.
  • Improved and innovative user interface.
  • Improved graphics and controls.
  • Intuitive operation thanks to touch functions and buttons.
  • Communication interface for several PLCs.
  • Versions for PROFIBUS or PROFINET.
  • Possibility of storing data on a USB key.
  • Compatible with SIMATIC HMI Comfort and SIMATIC HMI Basic 4″ and 6″ displays.

Companies that implement the next generation of UX (User Experience) solutions early on will have a competitive advantage in the future thanks to their advanced efficiency. Here are some of the new visualization systems from Siemens.

HMI screen Ktp700 Basic 7″ 800 × 480 IP65, Siemens
HMI screen Ktp700 Basic 7″ 800 × 480 IP65, Siemens


Omron offers a wide range of different types of human-machine interfaces. Omron NA Series HMI, Omron Compact HMI, NQ5 HMI, PC Based HMI, HMI and Control, Scalable HMI, NT25 HMI and Function Key HMI. All of these devices have a slightly different function and are designed for different applications. However, the main advantage of the new generation of machine interfaces is that these devices improve control and monitoring and allow a better connection between the operator and the machine.

Key Benefits of Omron NA Series HMI:

  • Clear and bright display with 1280×800 high resolution.
  • All models are available in a variety of 7-inch, 9-inch, 12-inch, and 15-inch widescreens.
  • Two Ethernet ports allow simultaneous access from the control and maintenance segments.
  • NJ variables are shared in the NA project to reduce development time, and NA applications are tested against the NJ program using a simulator.
  • Sysmac Studio offers an integrated development environment.
  • Many security features include runtime permission settings and runtime restrictions with credentials.
  • Multimedia, such as video and PDF.
Programmable HMI 15″ 1024 × 768 IP65, Omron Industrial Automation
Programmable HMI 15″ 1024 × 768 IP65, Omron Industrial Automation

These are just a few of the HMI panels offered by manufacturers out there. Based on your needs, you can find many touch screens from other brands in the market.

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