Self-testing proximity testing systems and corresponding methods are discussed herein and can include a proximity probe and controller in electrical communication via a cable. A self-testing subsystem can be in communication with the controller and configured to determine whether proximity probes and cables assembled with a controller are compatible or incompatible. The self-testing subsystem can place a known impedance in electrical communication with the controller, modifying a proximity signal output by the controller. When the modified proximity signal differs from a predicted proximity signal by greater than or equal to a threshold amount, the self-testing subsystem can output a first indication indicating that incompatible proximity probes and cables are assembled with a controller. When the modified proximity signal differs from a predicted proximity signal by less than the threshold amount, the self-testing subsystem can output a second indication indicating that compatible proximity probes and cables are assembled with a controller.

An oscillating sensor device, particularly for a proximity sensor, for sensing a dynamic change of attenuation caused by a measurable physical effect includes an oscillator including a resonance circuit and an amplifier fed back to the resonance circuit and configured to maintain oscillation of the oscillator, and a control unit configured to control the open loop gain of the oscillator. The amplifier comprises a non-linear gain characteristics defining an operating point at a preset amplitude of oscillation. The control unit is configured to control the open loop gain of the oscillator so that the operating point is set to a preset amplitude of the oscillation.

A safety switch comprises a switching device (2) having a casing (4) housing switching means (5) connected to one or more circuits, an operating device (3) interacting with the switching means (5) for opening/closing the circuits, an unlocking mechanism (13) having an unlocking pin (14) translating with a maximum stroke from a locking position of the access to an unlocking position to operate the opening of the switching means (5), detection means (17) of the stroke of the unlocking pin (14) having a first detector (18) of the start of the stroke of the unlocking pin (14), an auxiliary unlocking control (25, 26) operatively connected to the unlocking mechanism (13) from a rest position to an operative position of unlocking of the access and promote the translation of the unlocking pin (14) The detection means (17) comprise an auxiliary detector (31) for detecting the actuation of the auxiliary unlocking control (25, 26).

A safety switch with detection of the end-stroke of the unlocking mechanism adapted to supervise a safety access of a machine or industrial plant comprises a switching device (2) adapted to be associated to the fixed part of an access to be supervised and having switching means (5) adapted to be operatively connected to one or more control and/or service circuits of the plant for the control thereof, an operating device (3) associated to a movable part of the access to interact with the switching means (5) at the time of opening/closing of the access for opening/closing of one or more circuits, an unlocking mechanism (13) housed in the switching device (2) and having an unlocking pin (14) adapted to translate with maximum predetermined stroke from a blocking position of the access to an unlocked position to determine the opening of the switching means (5), means (17) for the detection of the stroke of the unlocking pin (14) comprising a first detector (18) adapted to detect the start of the stroke of the unlocking pin (14) and a second detector (19) adapted to detect the end of the stroke of the unlocking pin (14).

The invention relates to an inductive proximity switch having a primary coil for generating an alternating magnetic field, with an oscillator for driving the primary coil, with a control and evaluation unit, which is operatively connected to the oscillator and is equipped to acquire and evaluate an amplitude and a phase position of a current in the primary coil and for outputting a detection signal depending on the acquired current in the primary coil, with at least one compensation coil for manipulation of the alternating magnetic field generated by the primary coil. The inductive proximity switch is characterized in that a separate controllable current source is present for controlling the at least one compensation coil.

A safety switch (1) having a reading head (2) and an actuator (3) having a transponder (4) and being movable relative to the reading head (2). Encoded signals of the transponder (4) are detectable by means of the reading head (2). As a means for detecting encoded signals, the reading head (2) has a resonant circuit (6) controlled by a processor unit, with the distance between the actuator (3) and reading head (2) being determined by means of an amplitude evaluation of the signals of the transponder (4) detected with the resonant circuit (6). Control signals are generated as a function of the distance signals thus determined.

A sensor element of an inductive proximity sensor or distance sensor contains a coil arrangement with at least one excitation coil and at least one receiving coil and includes an electrically conductive shielding which contains a shielding cup that surrounds the coil arrangement laterally and on the rear face. A method operates the sensor element. The shielding of the sensor element further contains a flange which is provided on the front face of the sensor element, is connected to the shielding cup in an electrically conductive manner, and completely surrounds the coil arrangement.

A method for shielding an inductive sensor includes arranging an annular shielding coil outside an annular detection coil, the shielding coil surrounds the detection coil, and the radial thickness of the shielding coil is smaller than that of the detection coil. An inductive sensor adopting the above method for shielding the inductive sensor, in which the shielding coil is arranged outside the detection coil of the inductive sensor, magnetic fields generated by the two coils are opposite in direction and partially cancel out each other. When interference exists, the magnetic fields generated by the two coils are influenced at the same time and are attenuated or increased by identical strength. Therefore, the summed magnetic field strength can be kept constant, resonance voltages cannot be attenuated, the interference rejection of the inductive sensor is improved, and the sensitivity of the inductive sensor is not influenced.

A machinery brake of an elevator includes a frame part including an electromagnet, an armature part, an inductive proximity sensor indirectly mounted to one of the following: the frame part, the armature part, and a target mounted to another of the following: the frame part, armature part. The machinery brake further includes, for establishing the indirect mounting: a temperature change compensation device mounted between the inductive proximity sensor and one of the following: the frame part, the armature part. Some aspects relate to a method for compensating a change in switching point of an inductive proximity sensor.

Front-end circuits that combine inductive and capacitive sensing are described. In one embodiment, an apparatus includes a plurality of inductive elements, an inductive measurement circuit, and a frequency divider circuit. The inductive measurement circuit is to output a first signal with a first frequency. The first signal is associated with an inductance change of one of the inductive elements. A feedback circuit can maintain the sinusoidal operation of the first signal. The frequency divider circuit can generate a second signal with a second frequency that is lower than the first frequency.