Today’s HMI (human machine interface) systems safeguard the safe control of ever larger and more complex equipment e.g. for multi-machine control in mechanical and plant engineering or multi-function control in traffic engineering. Operating personnel are required to take on more responsibility, which requires the availability of suitable electronic HMIs. “Operator error” can be responsible for serious damage to equipment as well as to people and the environment. In order to avoid this, the operator’s data display, on which his decisions are based, must at all times be correct.
UNNOTICED DISPLAY OF INCOORECT DATA can result from an erroneous technical data transfer to the monitor, an error in the graphics control of the display, the visualization software, the operating system, the driver of the TFT signal or the microprocessor itself. Also present could be data corruption in the graphics memory of the screen or a falsification through the graphics processor or its software.
Display safety can be achieved through the integration into the HMI of the safe electronic circuit Icontrust technology by Deuta-Werke. For example, the technology is already integrated in such CAN-capable displays as MFT L11, MFT 5/1 and MFT 2/1. It continuously watches dedicated areas on the screen and distinguishes between safety relevant and non-safety relevant information. It can monitor over 100 (also overlapping) areas. All pieces of information can be monitored independently in various areas of the screen as graphics, symbols, needle instruments, text or color-coding. It is possible to have different screen representations for the same data. When anomalies occur, a corresponding customer-specific defined safety reaction is triggered. For each area, in each refresh cycle the displayed image is analyzed and compared, using a “finger print” coding method, with the value of the respective input signal from the safeguarded process computer. These values are checked against a reference table initialized during the set-up. Set-up and maintenance can be done by the customer, all needed training and documentation will be provided.
The components used in this patent pending technology are available long term from Deuta-Werke with a contractual assurance. The circuit logic can be adapted for specific customer requirements without software modifications. It is suited for applications using safety relevant representation of information, for example, in the cockpits of modern trains, in all kinds of control rooms or manned surveillance systems. The technology can be used as a panel PC, a TFT monitor or a projector. It can also be integrated as an add-on or a design-in into existing devices (for functional safety requirements up to SIL 4).
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