Isolated multipath 4-20mA-current signal output circuit

Abstract

The invention discloses an isolated multipath 4-20mA-current signal output circuit, comprising a PWM (Pulse-Width Modulation) module, an isolating and shaping module, a filtering module, a V / I conversion module and an AC / DC (Alternating Current / Direct Current) power module, wherein the PWM module is used for generating a PWM waveform corresponding to an MCU (Microprogrammed Control Unit) control value; the isolating and shaping module is used for isolating the received PWM signal and recovering the waveform of the PWM signal; the filtering module is used for filtering the received PWM signal to convert the PWM signal into DC voltage; the V / I (Voltage / Current) conversion module is used for converting the DC voltage into current signal to output; and the AC / DC power module is used for supplying power to the isolating and shaping module, the filtering module and the V / I conversion module. According to the invention, digital-to-analog conversion is realized by adopting PWM output and RC (Resistor-Capacitor) filtering, and 12-bit precision is realized; the isolating and shaping module is utilized to realize the isolation and waveform recovery of the PWM signal; the V / I conversion module is utilized to realize the stable current output; and the AC / DC power module is utilized to realize the power isolation for multipath current output and supply a stable voltage.

Description

technical field [0001] The invention relates to an isolated multi-channel 4-20mA current signal output circuit. Background technique [0002] In industrial applications, it is generally necessary to measure various non-electrical physical quantities, such as temperature, pressure, speed, angle, etc.; in addition, electrical physical quantities (referred to as electricity), such as current, voltage, power, frequency, etc., need to be converted into standard analog electrical signals. Transmission to the control room or display equipment hundreds of meters away. The most widely used standard analog electrical signal in the industry uses 4~20mA DC current to transmit analog. The reason for using the current signal is that it is not easy to be disturbed, and the internal resistance of the current source is infinite, and the resistance of the wire connected in series in the loop does not affect the accuracy, and it can be transmitted hundreds of meters on an ordinary twisted pai...

AI Technical Summary

Problems solved by technology

[0011] It can be seen that the above-mentioned existing solutions for transmitting analog quantities with standard analog electrical signals obviously still have inconveniences and defects in structure and use, and need to be further improved urgently.

In order to solve the problems existing in the existing solutions of using standard analog electrical signals to transmit analog quantities, relevant manufacturers have tried their best to find a solution, but no suitable design has been developed for a long time, and general products There is no appropriate structure to solve the above problems, which is obviously a problem that relevant industry players are eager to solve

Images