ABB supports the first Safe HMI with in-built Profinet/Profisafe

Under development by Deuta-Werke in collaboration with ABB, the Safe HMI accurately and safely displays either the train's speed or the status of various safety zones. Fail-safe selections through user touch events and fail-safe graphical objects, like train speed or selected operating modes, can be exchanged between the Safe HMI and the ABB AC500-S safety PLC.

Deuta-Werke is a world leader in the design and manufacture of systems, solutions and functional safety components for railway applications. The company's continuous pursuit of the highest safety standards results in developing the Safe HMI as a safer way to visualise train speed, select operating modes and status of safety zones up to SIL3.

Deuta-Werke uses its IconTrust and SelectTrust technologies to develop Safe HMIs for train applications. For example, IconTrust technology simultaneously and independently monitors the safety-critical areas on the HMI screen. Should there be a deviation, it triggers a corresponding safety-oriented response. This can be sent through Profinet/Profisafe to the AC500-S safety PLC for a more controllable safety reaction. Each of the individual displayed fail-safe areas is analysed and compared to the value of the respective input variable during every image refresh cycle of the Safe HMI.

SelectTrust technology enables fail-safe selection on the Safe HMI using its touch screen commands. The selected value can be sent through Profinet/Profisafe to the AC500-S safety PLC for further safety logic processing such as safely changing the operating mode of the application or changing safety process parameters.

Replacing hard-wired elements

Using SelectTrust technology on Safe HMIs can replace several hard-wired control elements on mechanical control panels. This improves the railway application usability and safety, reduces operating costs and increases application productivity.

With SIL3 Safe HMI versions, whenever a driver operates a touchscreen, two touch layers, situated one behind the other, are activated, feeding a comparative signal to a safety unit on the Safe HMI. The safety unit evaluates the touch event and translates it into a safety value, which is safely transferred to ABB's safety PLC using Profinet/Profisafe communication.

By transferring the Profinet/Profisafe values to ABB's safety CPU, the state of selection can be saved using the AC500-S safety CPU's flash memory, ensuring that all events have persistent status. The flexibility of Structured Text and the ability to implement complex logic to handle and store all these selection states on the Safe HMI, are critical to the system's success. Furthermore, the ability to distribute Safe HMI information to more than one controller using not only Profinet/Profisafe IO Controller but also Profinet/Profisafe IO Device functionality is critical to the selection.

ABB's Yauheni Veryha, product manager - Safety PLC says: "While functional safety dominates industrial machinery, it is now the rail sector which is placing a high priority and investing to further improve its train safety. Deuta-Werke selected ABB and its AC500-S safety PLC as the technology partner to implement Profinet/Profisafe on its Safe HMIs. We advised the company on the best way to implement Profinet/Profisafe. The company is using the AC500-S safety PLC as a Profinet IO controller and Profisafe F-Host with the advanced safety application on it using Structured Text for safety programming. This is used to communicate with the Safe HMI with Profinet IO device and Profisafe F-Device functionality. It provides advanced safety control solution with Safe HMI and the state-of-the-art industrial Profinet/Profisafe communication for railway application customers."

In the future, it is hoped that the Safe HMI will be adapted for industrial applications. Safe HMI offers a digital replacement for pressing a mechanical safety control button. Safe HMI enables the removal of various mechanical control elements within operator control rooms without compromising on functional safety. Having the Safe HMI provides many potential benefits like costs savings, improved usability, higher flexibility to adapt to changes in the control layout, adaptation to national language support and many more.

Learn more at www.abb.com.