The present invention relates to an apparatus (1) for determining and/or monitoring at least one process variable of a medium (2) in a containment (3), comprising a first oscillatory element (11a) and a second oscillatory element (11b), a first driving/receiving unit (12a) and a second driving/receiving unit (12b), and an electronics (6), wherein the first driving/receiving unit (12a) is embodied to excite the first oscillatory element (11a) by means of a first electrical excitation signal (U.sub.E1) to execute mechanical oscillations, and to receive the mechanical oscillations of the first oscillatory element (11a) and to convert such into a first electrical, received signal (U.sub.R1), wherein the second driving/receiving unit (12b) is embodied to excite the second oscillatory element (11b) by means of a second electrical excitation signal (U.sub.E2) to execute mechanical oscillations, and to receive the mechanical oscillations of the second oscillatory element (11b) and to convert such into a second electrical, received signal (U.sub.R2), and wherein the electronics (6) is embodied to determine the process variable from the first received signal (U.sub.R1) and/or the second received signal (U.sub.R2).

The invention provides a method of driving a vibrating sensor in which the drive signal is combined with an amplitude modulated high frequency carrier. The signal is demodulated at a position adjacent to the component to be driven. This method may be applied to reducing cross-talk between drive and pick-up wire pairs and also to passing both drive and pickup signals, and two drive signals, down the same wire pair.

The present invention relates to a method for monitoring state of a coil having at least two connection wires, which coil is part of an apparatus for determining at least one process variable of a medium in a containment, as well as relating to an apparatus for executing the method. The method, in such case, includes method steps as follows: ascertaining a desired-value of an ohmic total resistance for the coil and the connection wires, supplying the coil with an electrical excitation signal and receiving an electrical, received signal from the coil by means of the two connection wires, ascertaining an actual-value of the ohmic total resistance based at least on the received signal, and comparing the actual-value with the desired-value and ascertaining a state indicator based on the comparison.

A separation system and method, of which the system includes a separation device comprising a mixed fluid inlet, a first outlet, and a second outlet, a tank coupled to the second outlet and configured to receive a solid from the separation device via the second outlet, and a solids-level sensor extending through the tank and positioned at an elevation above a bottom of the tank. The solids-level sensor is configured to detect a viscosity of a material within the tank at the elevation.

The a vibration sensor comprising a membrane that can be stimulated so as to oscillate by means of a piezoelectric drive, and a mechanical oscillator arranged on the membrane, at least one piezoelectric element of the drive comprising at least one first electrical contact structure on an upper side of the piezoelectric element and at least one second electrical contact structure on a lower side of the piezoelectric element, such that the at least one piezoelectric element is designed so that an active area of the piezoelectric element corresponds to an area of a mechanical deformation of the unidirectional curvature of the membrane, during a pre-defined eigenmode of the mechanical oscillator.

The invention provides a level switch having a near field communications facility which allows at least some functions of the switch to be powered and the communication of data between the switch and a reader. Application and calibration information are examples of data that can be read to and from the switch, both in the factory and in the field.

An apparatus for determining and/or monitoring at least a first process variable of a medium and method for operating the apparatus at least with an electronics unit and a sensor unit, wherein the electronics unit is embodied to supply the sensor unit with an excitation signal, which is composed of an excitation carrier signal with an excitation carrier frequency and an excitation modulation signal with an excitation modulation frequency, and to receive from the sensor unit a received signal, which is composed of a received carrier signal and a received modulation signal, and wherein the electronics unit is embodied to determine from the phase shift between the excitation modulation signal and the received modulation signal at least the first process variable.

The present invention relates to a method for monitoring a condition of a vibronic sensor, which serves for determining and/or monitoring at least one process variable of a medium in a container and which includes at least one sensor unit having a mechanically oscillatable unit. The method includes steps of ascertaining a measured value for at least one physical and/or chemical variable (f, f.sub.0) characteristic for the vibronic sensor, while the sensor is located at/in its location of use, comparing the measured value of the physical and/or chemical variable (f, f.sub.0) with a reference value (f.sub.ref, f.sub.0,ref) for the variable, and ascertaining a condition indicator from the comparison.

A vibration sensor comprising an oscillatable unit, which is composed of a membrane with an inner surface and an outer surface and, in given cases, at least one oscillatory element secured on the outer surface of the membrane. A transmitting/receiving unit is provided, which with a predetermined exciter frequency excites the oscillatable unit to execute oscillations and which receives oscillations of the oscillatable unit. A control/evaluation unit is provided, which signals reaching of the predetermined fill level or ascertains the density, respectively the viscosity, of the medium. In order to be able to apply the vibration sensor in high temperature applications, a disc shaped element of a magnetostrictive material is provided, which has a force transmitting connection with the inner surface of the membrane. The transmitting/receiving unit is an electromagnetic drive.

The invention describes a vibrating fork point level switch with multiple switching points.