Abstract: A field device for process instrumentation, in particular a measuring transducer, comprising an analogue output to which a two-wire line is connectable for transmitting an analogue output signal. The output circuit contains a controller with an actuator connected downstream for the analogue output signal. A monitoring unit monitors whether an actuating signal remains within a predeterminable value range to monitor the output circuit for correctly setting the loop current. If the actuating signal is outside the value range, an indicator signal is output to a computing unit so that suitable measures can be introduced in response to an error state that has thus been identified.

Abstract: A method for accurately acquiring multiple analog input signals that are converted using a plurality of A/D converters into corresponding digital single measured values. A first measurement averaging cycle having a predetermined total number of measuring intervals is predetermined by a higher-order control unit. First and second input signals are acquired by first and second A/D converters in a first and second number of measuring intervals, the second number being smaller than the first number. The first and second input signals are averaged to form first and second measured values, respectively. The first input signal is acquired by the second A/D converter in a third number of measuring intervals as at least one further single measured value.

Abstract: A field device for process instrumentation having an interface for connecting a two-wire cable and for outputting measurement values, wherein the interface comprises a series circuit having a transistor circuit by which the loop current is adjustable as a function of a control signal, a power supply, and a device by which the loop current can be captured as an actual value that is fed by a first feedback coupling to a regulator having integrated behavior. The regulator compares the actual value to a target value, and generates a control signal for the transistor circuit. The actual value is fed by a second feedback coupling to a summation point as a compensation signal for generating an input signal for the transistor circuit as a function of the control signal and the compensation signal to suppress interference coupled into the two-conductor line.

Abstract: A field device for process instrumentation having an interface for connecting a two-wire cable and for outputting measurement values, wherein the interface comprises a series circuit having a transistor circuit by which the loop current is adjustable as a function of a control signal, a power supply, and a device by which the loop current can be captured as an actual value that is fed by a first feedback coupling to a regulator having integrated behavior. The regulator compares the actual value to a target value, and generates a control signal for the transistor circuit. The actual value is fed by a second feedback coupling to a summation point as a compensation signal for generating an input signal for the transistor circuit as a function of the control signal and the compensation signal to suppress interference coupled into the two-conductor line.

Abstract: A method for securely acquiring multiple analog input signals that are converted using a plurality of A/D converters into corresponding digital single measured values. A first measurement averaging cycle having a predetermined total number of measuring intervals is predetermined by a higher-order control unit. First and second input signals are acquired by first and second A/D converters in a first and second number of measuring intervals, the second number being smaller than the first number. The first and second input signals are averaged to form first and second measured values, respectively. The first input signal is acquired by the second A/D converter in a third number of measuring intervals as at least one further single measured value.

Abstract: A field device for process instrumentation, in particular a measuring transducer, comprising an analogue output to which a two-wire line is connectable for transmitting an analogue output signal. The output circuit contains a controller with an actuator connected downstream for the analogue output signal. A monitoring unit monitors whether an actuating signal remains within a predeterminable value range to monitor the output circuit for correctly setting the loop current. If the actuating signal is outside the value range, an indicator signal is output to a computing unit so that suitable measures can be introduced in response to an error state that has thus been identified.

Abstract: A field device having an analog output, i.e., a measuring transducer, for process instrumentation having a 4-20 mA interface as the analog output. For digital-to-analog conversion, a digital value is split into a digital coarse portion and a digital fine portion. Depending on the digital coarse portion, a first analog signal is generated using a pulse width modulator having a downstream mounted low path filter and a signal above the analog output signal, and a second output signal using a pulse width modulator also having a downstream mounted low path filter with a signal below the analog output signal. The analog signals are supplied to a third pulse width modulator controlled with the digital fine portion, where a low-pass filter (TP3) is downstream mounted. As a result, an analog output signal is provided having a high resolution and good dynamic properties. In addition, the field device is provided with a digital-to-analog converter that can be produced having minimal complexity.