Abstract: Field devices comprising a transmitter and/or receiver for wireless data communication are provided. The energy available for wireless data communication in data transmitting or data receiving field devices is evaluated prior to activation of the transmitter and/or receiver of the field device.

Abstract: Field devices comprising a transmitter and/or receiver for wireless data communication are provided. The energy available for wireless data communication in data transmitting or data receiving field devices is evaluated prior to activation of the transmitter and/or receiver of the field device.

Abstract: In one general aspect, data transfer between the modem and a processor connected to the modem may be improved using a variable speed buffer. The variable speed buffer may include one or more first-in/first out buffers (FIFOs) and two interfaces. The FIFOs may be connected between the interfaces to form an input data path and an output data path. Each FIFO may store a complete message. Consequently, an entire message may be transferred from the processor at the processor's higher data rate without having to wait for a modulator to modulate the outgoing message at a slower data rate. The modem automatically may use characteristics of an incoming signal to detect which communications protocol is used to send a message, and perform protocol specific functions. The modem may perform system diagnostic functions to improve system performance.

Abstract: Field devices comprising a transmitter and/or receiver for wireless data communication are provided. The energy available for wireless data communication in data transmitting or data receiving field devices is evaluated prior to activation of the transmitter and/or receiver of the field device.

Abstract: Field devices comprising a transmitter and/or receiver for wireless data communication are provided. It is proposed to evaluate the energy available for wireless data communication in data transmitting or data receiving field devices prior to activation of the transmitter and/or receiver of the field device.

Abstract: A 4–20 mA interface circuit is disclosed having a resistor in series with a DC/DC converter, and further having a current bypass circuit in parallel to the series combination of the resistor and DC/DC converter. In this way, a 4–20 mA analog current at a low frequency may be bypassed around the series combination, whereas a high-frequency current carrying a digital communications signal may be presented with the resistor as its only effective input impedance. In this way, the 4–20 mA current sees an input impedance which allows the 4–20 mA current to be used in supplying power to an external device, whereas the high-frequency current sees an impedance which allows a reliable, low-distortion reading of the digital communications signal therefrom. The high-frequency current may be superimposed on the 4–20 mA, low-frequency current.

Abstract: A valve controller is disclosed. The valve controller includes an interface circuit having an input for connection to a controller, a processor in data communication with the interface circuit which is operable to generate a control signal for controlling a valve position, and a control device operable to control the valve position in response to the control signal from the processor. The interface circuit includes a power extraction circuit connected to the controller and is further operable to generate a DC operating voltage for use in powering the interface circuit and the processor. The interface circuit includes a current sensor connected to the controller and is further operable to generate a measure of a current from the controller, the measure being used in controlling a device associated with the interface circuit. The interface circuit also includes a digital communications circuit connected to the controller and is further operable to transmit and receive communication signals.

Abstract: A valve controller is disclosed. The valve controller includes an interface circuit having an input for connection to a controller, a processor in data communication with the interface circuit which is operable to generate a control signal for controlling a valve position, and a control device operable to control the valve position in response to the control signal from the processor. The interface circuit includes a power extraction circuit connected to the controller and is further operable to generate a DC operating voltage for use in powering the interface circuit and the processor. The interface circuit includes a current sensor connected to the controller and is further operable to generate a measure of a current from the controller, the measure being used in controlling a device associated with the interface circuit. The interface circuit also includes a digital communications circuit connected to the controller and is further operable to transmit and receive communication signals.

Abstract: A 4-20 mA interface circuit for use, for example, in a valve controller, communicates with a two-wire loop. The interface circuit includes a power extraction circuit connected to the two-wire loop and operable to generate a DC operating voltage for use in powering the interface circuit and a related device, the power extraction circuit including a DC-to-DC converter that generates the DC operating voltage as a voltage having a smaller magnitude than a voltage between the two wires of the two-wire loop. The circuit also includes a current sensor connected to the two-wire loop and operable to generate a measure of an analog current through the two-wire loop, the measure being used in controlling a device associated with the interface circuit, and a digital communications circuit connected to the two-wire loop. The digital communications circuit is operable to inject a digital transmission signal on to the two-wire loop and to extract a digital reception signal from the two-wire loop.

Abstract: A 4-20 mA interface circuit is disclosed having a resistor in series with a DC/DC converter, and further having a current bypass circuit in parallel to the series combination of the resistor and DC/DC converter. In this way, a 4-20 mA analog current at a low frequency may be bypassed around the series combination, whereas a high-frequency current carrying a digital communications signal may be presented with the resistor as its only effective input impedance. In this way, the 4-20 mA current sees an input impedance which allows the 4-20 mA current to be used in supplying power to an external device, whereas the high-frequency current sees an impedance which allows a reliable, low-distortion reading of the digital communications signal therefrom. The high-frequency current may be superimposed on the 4-20 mA, low-frequency current.

Abstract: To enable a relatively constant output voltage at a DC/DC converter of a field device during a predictable time after shut-down of energy supplied to the DC/DC converter there is proposed a load voltage controller having a comparison unit adapted to compare the load voltage signal (Uo) with an externally supplied load voltage reference signal (Uref). When the load voltage (Uo) exceeds the load voltage reference signal (Uref) an energy buffer stores supplied energy for subsequent resupply to the load of the field device.

Abstract: To detect a power supply failure on an intrinsically safe field bus of a manufacturing process control system in an efficient manner there is provided a field device with a discharge protection unit which is connected to a control bus for supply of an operating current from the control bus to the field device. The discharge protection unit inhibits a discharge of energy stored in the field device to the control bus. The field device also comprises a controller unit adapted to control the operation of the field device and being powered with the operating current from the control bus. According to the present invention the discharge protection unit comprises at least two rectifying elements inserted into the current path of the operating current with identical conducting directions and an input signal or an output signal of a selected rectifying element is supplied as interrupt signal to the controller unit for power supply failure detection.

Abstract: To enable a relatively constant output voltage at a DC/DC converter of a field device during a predictable time after shut-down of energy supplied to the DC/DC converter there is proposed a load voltage controller having a comparison unit adapted to compare the load voltage signal (Uo) with an externally supplied load voltage reference signal (Uref). When the load voltage (Uo) exceeds the load voltage reference signal (Uref) an energy buffer stores supplied energy for subsequent resupply to the load of the field device.

Abstract: To detect a power supply failure on an intrinsically safe field bus of a manufacturing process control system in an efficient manner there is provided a field device with a discharge protection unit which is connected to a control bus for supply of an operating current from the control bus to the field device. The discharge protection unit inhibits a discharge of energy stored in the field device to the control bus. The field device also comprises a controller unit adapted to control the operation of the field device and being powered with the operating current from the control bus. According to the present invention the discharge protection unit comprises at least two rectifying elements inserted into the current path of the operating current with identical conducting directions and an input signal or an output signal of a selected rectifying element is supplied as interrupt signal to the controller unit for power supply failure detection.

Abstract: Field devices comprising a transmitter and/or receiver for wireless data communication are provided. It is proposed to evaluate the energy available for wireless data communication in data transmitting or data receiving field devices prior to activation of the transmitter and/or receiver of the field device.

Abstract: The present invention includes an electropneumatic positioner having an external binary input block which provides access to the electrical output of an integral electronic position controller to control operation of a valve relay. The invention enables manual control of the positioner for safety, maintenance etc.