Ifm Electronic Gmbh

Ifm Electric Gmbh

Heinz Walter

Manfred Maurus

Alfred Wagner

Peter Kimbel

Dorin Antonovici

Alexander Oppe

The invention relates to a transmitter for transmitting a process variable to a programmable logic controller. In a current mode a 4-20 milliamp current is fed into a burden and in a voltage mode 0-10 Volt signals are generated. The transmitter includes a process value input, a current stage, a voltage stage and a U/I output for the current or the voltage signal, and a U/I control input for switching between the two modes. The transmitter is configured to feed a current which is dependent on the voltage across the burden into the current stage via a resistor and thus to compensate for a current loss at the voltage stage which is dependent on the voltage across the burden.

Transmitter for transmitting a process variable to a programmable logic controller

The disclosure relates to a method for operating a capacitive pressure measurement device. In order to achieve an insensitivity to external signal sources, the disclosure proposes continuously varying the working frequency of the pressure measurement device so that a resonance formation with externally injected (interfering) frequencies is avoided.

Capacitive pressure measurement device with varying frequency

The disclosure relates to a method for monitoring the operation of a pressure measuring cell of a capacitive pressure sensor, wherein the pressure measuring cell comprises a pressure-dependent measuring capacitor and a pressure-dependent reference capacitor and the pressure measuring value is obtained as a measuring signal from the capacitance values of the measuring capacitor and the reference capacitor, wherein the measuring signal is supplied to an evaluation unit in the form of an alternating square-wave signal, the pulse height of the signal depending on quotients of the capacitance values of the reference capacitor and the measuring capacitor and the period of the signal being determined by the capacitance value of the measuring capacitor such that, in the nominal pressure range of the pressure sensor, there is a fixed correlation between the pulse height and the period, wherein the pairs of values of pulse height and period (h1, d1), . . . , (hn, dn) are stored as nominal values in an adjustment procedure for determined pressure values p1, . . . , pn, and wherein, for the currently measured pressure value px, with the pair of actual values (h, d), the pair of nominal values (h, d) is determined, and if there is significant deviation between the pair of actual values and the pair of nominal values, an error signal is generated.

Method for monitoring the operation of a pressure measuring cell of a capacitive pressure sensor

A protective circuit for protecting an output stage in the event of faulty contacting of the electrical connections, wherein the output stage includes a driver unit and has an analog or digital signal output is provided. Accordingly, in order to protect the output stage from a faulty connection in a simple and economical manner, the protective circuit comprises a first transistor circuit, which is connected in series between the output stage and the signal output, and a second transistor circuit, which is connected in series between the negative supply connection and the signal output. The second transistor circuit is connected to the base of the first transistor circuit in order to influence the first transistor circuit in such a way that the first transistor circuit becomes highly resistive in the event of a fault.

Protective circuit for a signal output stage in event of faulty contacting of electrical connections

A method for monitoring the operation of a pressure measuring cell () of a capacitive pressure sensor (), wherein the pressure measuring cell () has a measuring capacitor (C) and a reference capacitor (C) and the pressure measuring value (p) is obtained from the capacity values of the measuring capacitor (C) and the reference capacitor (C), characterized in that a control pressure measuring value (p') is obtained with an auxiliary capacitor (C) arranged outside the pressure measuring cell () and the operability of the pressure measuring cell () is inferred by comparing the pressure measuring value (p) to the control pressure measuring value (p&#x2032;) is provided.

Method for self-monitoring a ceramic pressure measuring cell of a capacitive pressure sensor and evaluation circuit for carrying out said method

A circuit arrangement is described for selectively generating an analog current output value or an analog voltage output value as a function of an analog input value. Optionally, the analog current output value or the analog voltage output value may also be a function of an input base value or a signed input correction value. The circuit arrangement includes a current control unit, a voltage control unit, a current output source is triggered by the current control unit, and a voltage output source triggered by the voltage control unit. The current output source and voltage output source of the circuit arrangement may be triggered in parallel and are connected in series on the output side.

Circuit arrangement for selective generation of an analog current output value or an analog voltage output value

An electronic pressure switch has only two terminals, a resistance measuring bridge pickup, an amplifier unit downstream of the resistance measuring bridge, a comparator connected to the amplifier unit and a switching stage downstream of the comparator achieves a lower residual current in the blocked state and a lower voltage drop in the switched state. The resistance measuring bridge has a high internal resistance and the amplifier unit supplies both an analog measurement signal corresponding to the analog measured value of the resistance measuring bridge and a threshold value to the comparator at low resistance. A high-resistance balancing network is assigned to the resistor network, and an in-phase regulator on the input side limits and controls the supply voltage of the resistance measuring bridge, the amplifier unit, the comparator and the balancing network and the switching stage is made as a shunt controller triggered by the output of the comparator.

Electronic pressure switch

An electrical transducer has a sensor outputting a value corresponding to the quantity to be measured, an analog end stage connected downstream of the sensor, a processor circuit, and an analog measurement signal transmission path. The end stage converts the sensor output signal into an impressed output current related to the magnitude of the quantity measured, the electronic transducer being controlled with the processor circuit. The electrical transducer can be scaled by the user, has low inherent power consumption and ensures high response speed because the processor circuit in normal operation is shifted temporarily into a sleep mode, in the analog measurement signal transmission path an analog scaling unit is inserted, the output signal of the sensor and at least one analog setting value are supplied to the analog scaling unit, and the output signal of the analog scaling unit is supplied to the analog end stage.

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Hergatz, Germany

Heinz Walter