Operation of Alarm Measuring Systems

Measuring systems. Analog transducers which sense temperatures, pressures, etc., in the process are connected to the system. The transducer output may be current, voltage or resistance. The input signal is filtered and normalized to a defined voltage level in the system.

The normalized measured value is connected across the system bus to the display unit when the push-button for manual measuring in the front of a module is depressed. The signal is scaled to its correct value before A/D conversion and presentation on the digital display with the correct number of decimals.

Information concerning scaling factor and number of decimals is programmed on each channel board, and is connected to the system bus at the same time as the measured value. It is possible to program eight different factors with a 3-bit binary code, and the number of decimals can be 0, 1 or 2.

The display is normally dark and is only lit up when a push-button for manual measuring has been depressed, the displayed value will follow the fluctuations of the signal. When the push-button is released, the value will remain unchanged for about five seconds.