Pepperl + Fuchs Gmbh

Rockwell Technologies, Inc.

Hermann Wieth

Igor Kurkovskiy

Robert J Kretschmann

Michael Wolfgang Kessler

Robin-David Slater

James William Clingersmith

Hans-Jurgen Schiefer

Daniel Royer

Richard A Ales

Systems and methods are provided for sensing or measuring capacitive or inductive reactance or changes in reactance in which the sensed reactance is coupled with a known resistance in a sensor circuit and a start signal is provided to the sensor circuit, and a programmable delay line is used to generate a programmable delay signal. The outputs of the programmable delay and the sensor circuits are compared to ascertain which transitions first, and the programmable delay value is adjusted in successive approximation fashion to identify a programmable delay that best represents the delay time of the sensor circuit from which the sensed reactance value can be determined.

System and method for high resolution sensing of capacitance or other reactive impedance change in a large dynamic range

Low voltage logic circuitry is used to permit an entire subsystem of an industrial controller to be placed within a hazardous environment to receive a high speed serial link and undertake the control of multiple control points without expensive and awkward long cable runs and electrically isolating circuits for each cable run. Energy and bandwidth limiting on the high speed link allows power levels commensurate with high data rates yet intrinsic safety of the media allowing it to freely pass in and out of the hazardous area. A mixture of intrinsically safe and non-intrinsically safe equipment on the same logical rack is allowed through a bus isolator providing isolated data communication in backplane fashion between modules while wholly isolating power transmission along the backplane.

Bus isolator for industrial control system providing intrinsically safe

A palm-button control system provides for machinery control with minimized operator hand pressure by use of capacitive switches and reduced susceptibility to radio frequency interference. The system employs first and second capacitive palm-button switches, both of which must be contacted before machinery is activated. Each capacitive palm-button includes a radio frequency sensor which functions to disable machine activation in the presence of a sufficiently strong radio signal. Circuitry for periodically testing the radio frequency sensors provides periodic visual operator feedback indicative of operability of the system. All controls are synchronized or enabled in accordance with a series of digital pulses.

Control-safe capacitive switch

An protection barrier provides voltage and current necessarily conveyed to hazardous, such as explosive, areas. The system includes a current sensing circuit which triggers a silicon control rectifier based crowbar circuit in the event over current is detected. This triggering, in turn, trips a relay severing the current path entirely. A reverse polarity circuit provides for immediate clamping of improperly bias connections in a similar crowbar arrangement, and also provides for tripping of the circuit breaker. Thermistors are also provided in current series in the event the circuit breaker fails to trip, or is forcibly bypassed. The circuit breaker additional provides a visual indicator when it is in the tripped position. The intrinsic barrier system is suitable to serving as a first stage protection to zener barrier modules as utilized in the prior art.

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Chagrin Falls, OH, United States of America

Hermann Wieth