Endress + Hauser Flowtec Ag

Hanspeter Schmid

Werner Tanner

Dirk Sutterlin

Martin Koch

Pascal Buchschacher

Alex Huber

The signal transmission system comprises a transmitter circuit, a receiver circuit and a signal cable. A current divider is formed by a terminating resistor between the signal conductors of the signal cable. The transmitter circuit drives a loop current. When the receiver circuit input voltage has a voltage level above a first switching voltage threshold value, the output voltage assumes a first voltage level. The output voltage maintains the first voltage level when the input voltage is below the first switching voltage threshold value but above a second switching voltage threshold value. The transmitter circuit is configured to modulate the loop current with at least two different non-zero magnitudes at successive times. The first magnitude is greater than a first switching current threshold value and the second magnitude is less than the first switching current threshold value and greater than a second switching current threshold value.

Signal transmission system

A method for monitoring a measuring device of automation technology, wherein the measuring device has a capacitive sensor the sensor has at least one capacitor, and the at least one capacitor is applied for determining or monitoring a process variable. A loss resistance of the at least one capacitor is measured by determining the charge state of the at least one capacitor at a first point in time and at a subsequent, second point in time, and, based on a change of the charge state between the first point in time and the second point in time, information is won concerning disturbance of the ability of the measuring device to function.

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Kuttigen, Switzerland

Hanspeter Schmid