Direct-current two-wire type proximity sensor fault detection circuit

Abstract

The invention provides a direct-current two-wire type proximity sensor fault detection circuit. By detecting working currents of a two-wire type proximity switch sensor, the working condition and open and short circuit faults of the sensor are judged, corresponding signals are output, and therefore the problems that sensor faults cannot be judged by detection equipment, leakage currents exist in direct-current two-wire type proximity sensor output, residual voltage of signals causes unstable levels, and the detection equipment cannot identify the situation that the residual voltage of the signals causes the unstable levels are effectively solved. The direct-current two-wire type proximity sensor fault detection circuit can be arranged between the sensor and control equipment such as a PLC and used for outputting fault output signals to the PLC or an alarm system or other devices, actions of giving an alarm or conducting emergency shutdown are carried out on the sensor faults, and therefore production accidents caused by the sensor faults can be effectively avoided. Compared with the prior art, no residual voltage or leakage current exists in sensor signals processed by the direct-current two-wire type proximity sensor fault detection circuit, and compatibility is better.

Description

technical field [0001] The invention relates to a proximity sensor, in particular to a DC two-wire type proximity sensor fault detection circuit. Background technique [0002] Proximity sensors are sensors that replace contact detection methods such as limit switches and are designed to perform detection without touching the detection object. The main object of its detection is a metal object. When the detected object is close to the sensing surface of the switch to the action distance, the switch can be activated without mechanical contact and any pressure, thereby driving DC electrical appliances or providing control for computer (PLC) devices. instruction. It has the advantages of reliable action, stable performance, fast frequency response, long application life, strong anti-interference ability, etc., and is widely used in machine tools, metallurgy, chemical industry, textile and printing industries. [0003] At present, proximity sensors can be divided into inductive...

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Problems solved by technology

[0004] For this reason, the purpose of the present invention is to provide a DC two-wire proximity sensor fault detection circuit to solve the problem that the drive equipment cannot judge the sensor fault, and there is a leakage current in the output of the DC two-wire proximity sensor, and the residual voltage of the signal causes the level to be unstable. , to detect problems that the device does not recognize

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