Universal signal input circuit of intelligent instrument

Abstract

The invention discloses a universal signal input circuit for an intelligent instrument, which belongs to the technical field of signal input circuits and comprises an input terminal 1, an input terminal 2 and an input terminal 3. An input signal is a current signal, the positive end and the negative end of the signal are connected with the input terminal 2 and the input terminal 3 respectively, the control signal SW0 is at a low level, the control signal SW1 and the control signal SW2 are at high levels, the MOS tubes Q1, Q2, Q3 and Q5 are switched on, and the MOS tubes Q4 are switched off. The circuit is simple, high in reliability, stable in performance and low in production cost; input signals are various in type and comprise direct current signals between 0-20 mA, direct current voltage signals between 0-10 V, eight thermal resistance signals, potentiometer signals between 0-5 kilohms, eight thermocouple signals and direct current mV signals between -100 mV and +100 mV; and the input signal type and the measuring range can be changed through the upper computer, and batch production, batch stock of users and equipment management are facilitated.

Description

technical field [0001] The invention relates to a signal input circuit, in particular to a general-purpose signal input circuit of an intelligent instrument, which belongs to the technical field of signal input circuits. Background technique [0002] In industrial field instrumentation applications, there are many types of input signals. Common current signals (4~20mA, 0~20mA), voltage signals (0~5V, 0~10V), thermal resistance, thermocouple signals, etc., the existing signal isolators, transmitters and other industrial field instruments are often Only a single type of analog input signal can be measured, and the range is fixed and cannot be modified, causing inconvenience to production use and equipment management. [0003] The existing general-purpose input smart meters generally have the disadvantages of complex circuits and high production costs, which are not conducive to large-scale popularization. SUMMARY OF THE INVENTION [0004] The main purpose of the present in...

AI Technical Summary

Problems solved by technology

The common ones are current signal (4~20mA, 0~20mA), voltage signal (0~5V, 0~10V), thermal resistance, thermocouple signal, etc. The existing industrial field instruments such as signal isolator and transmitter are often It can only measure a single type of analog input signal, and the range is fixed and cannot be modified, which will cause inconvenience to production use and equipment management.

[0003] Existing general-purpose input smart meters generally have disadvantages such as complex circuits and high production costs, which are not conducive to large-scale popularization

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