The latest generation of HMI screens combines the best features of traditional products with modern open-source hardware, software, and networking technologies to address the challenges faced by legacy products.
Operator HMI screen interface devices are a key element of industrial automation, but many products suffer from shortcomings and implementation barriers. The incorporation of new features such as ruggedness and ease of use allows operator interface devices to be used at the industrial edge and in other critical applications, combining the best features of classic HMIs with modern commercial technologies.
Electronic devices that allow operators to interact with automation systems are collectively referred to as human-machine interfaces (HMIs). Sometimes, more specialized devices built on non-personal computer (PC) computing platforms may be referred to as operator interface terminals (OITs). Integrating HMIs and OITs into automation systems is critical. They can provide more interface options than simple panel devices, and if changes are needed, the HMI or operator interface terminal can usually be reconfigured or reprogrammed at a much lower cost.
Some of the added operator interface features, however, still have some drawbacks that make HMIs too costly and difficult to maintain. To address these drawbacks, the latest HMI products have been designed to incorporate past experience while utilizing the latest commercial technology.
The first generation of HMI and operator interface terminals focused on allowing users to start and stop equipment, understand how the system is operating, and make appropriate adjustments.
Alarm and event logging, historical data and displaying trends were features that were added incrementally later. HMI screens and operator interface terminal configurations can be copied and saved, allowing relatively quick deployment of new equipment if old equipment is damaged or fails. Improved networking capabilities, particularly Ethernet and Wi-Fi, mean that HMI screens no longer need to be installed physically close to the machine. Multiple HMI screens can be installed in the field to provide interfaces in control rooms, machines, and offices.
These HMI screens and operator interface terminals offer many advantages over hard-wired panel devices, but also have some disadvantages.
-Limitations of proprietary hardware and software.
-Higher initial costs.
-Ongoing support and maintenance costs.
-Licensing complexity and costs.
-extensive engineer and operator training.
-The effort is required to integrate multiple platforms.
Dedicated operator interface terminals may employ proprietary hardware and software (see Figure 1). Manufacturers provide these devices to provide adequate control system interfaces in a relatively self-contained space. Because they are dedicated to the industrial market, they do not benefit from the commercial benefits of scale offered by consumer electronics, making them less competitive in terms of price/performance. However, they can often withstand harsh industrial environments and provide practical, maintainable solutions.
Figure 1: Operator interface terminals, typically used in proprietary and closed systems, are rapidly being replaced by more open systems.
With the introduction of more advanced PC-based HMI screens, the hardware is seen as a better value than previous solutions, offering flexibility and connectivity to users. However, it also had the disadvantage of increasing ongoing maintenance and support requirements.
Today, users expect elegant-looking devices, frequent free updates, and improvements to device operating systems and applications (Figure 2).
Figure 2: The proliferation of advanced consumer electronics has driven end-users to expect rich and intuitive human-machine interfaces with easy mobile access on all device types. However, the industrial market has been slightly slower to innovate compared to the larger consumer market, which is relatively small, not to mention more conservative compared to the personal electronics market, which is on the cutting edge of technology.
The latest generation of HMI screen products addresses these shortcomings by incorporating proven commercial technologies while including and building on the best features of previous generations of HMI screens and operator interface terminals.
The advantages offered include.
Open Source: Ideally, modern HMIs combine the robustness and ease of use of traditional operator interface terminals with the functionality and value of PC-based HMIs. This combination is possible when the hardware platform is based on a real-time open-source operating system like Linux, with no acquisition or licensing costs. The small footprint, hot-swappable components, local LED indicators, and other useful touch features make the platform more suitable for field use. Well-designed to deliver PC-level performance, even in challenging industrial environments, the hardware works as if it were used at home.
Affordable configuration: Customization is possible, but not required, as modern HMI hardware includes built-in standard features to meet most needs. PC-based HMI configuration software is reasonably priced with no restrictive licensing fees. End users can focus on applying the HMI to the most appropriate location without worrying about limiting tag counts or run times.
Web and cloud-based connectivity: When users take advantage of the web and cloud-based connectivity, more functionality can be achieved from modern HMIs. Data can be shared securely between databases and systems, and HMI screen visualization can be extended to any computer or mobile device that is authorized to host a web browser.
Mobile devices: Mobility is another key component of the modern HMI screen. Once the base device is installed and configured, any mobile device can be securely connected and become another HMI screen, providing greater flexibility for engineers and operations personnel.
Designers can focus more on what the HMI screen content and experience should be while alleviating the expense and complexity of the underlying platform. The latest generation of HMIs combines the best features of legacy products with modern open-source hardware, software, and networking technologies to address the challenges posed by legacy products.
Because these latest HMI screens can be easily and seamlessly networked and deployed to any typical mobile device, end users are finding that today's technology is meeting their needs at a price they can afford.