A water quality online monitoring device

Abstract

The present invention discloses a novel online water quality monitoring device, including a main controller, a power supply module, an RS-485 communication module, a PH signal acquisition module, a conductivity signal acquisition module, and an ORP and temperature signal acquisition module. The main controller is responsible for collecting digital signals of PH, ORP, conductivity, and temperature of water quality, responsible for controlling the frequency generator that excites external impedance when measuring conductivity, and responsible for interacting and parsing data and commands with a host computer; the PH signal acquisition module, the ORP and temperature signal acquisition module, and the conductivity signal acquisition module output digital signals corresponding to each parameter; the RS-485 communication module realizes the communication of the equipment. Integrating several monitoring parameters solves the problem of mutual interference between PH, ORP, and conductivity; each module exists independently, and the data is isolated and communicated, avoiding interference from the external environment, and ensuring the acquisition accuracy of various data and the stability of the equipment.

Description

Technical Field

[0001] The present invention belongs to an online water quality monitoring device, specifically a device that can realize online real-time monitoring of pH, ORP, conductivity and temperature in water quality. Background Art

[0002] With the development of economy, water pollution becomes more and more serious. All walks of life will face water quality related problems. For example, industrial water system will face scaling, microorganisms and sedimentation during use, resulting in great waste of water resources, equipment damage, and finally the water system cannot operate normally. In order to better monitor water quality problems, the state has introduced a number of policies to actively promote the implementation of relevant water quality monitoring.

[0003] PH, ORP, conductivity, and temperature are several commonly used parameters in the field of water quality, and are widely used in the fields of industry, agriculture, food, medical treatment, and environmental protection. PH is an indicator of the acidity and alkalinity of a solution. The PH value has a great influence on the physical chemistry and products of the solution. PH has become an indispensable parameter in the field of water quality; ORP redox potential is used to reflect the macroscopic redox properties of all substances in aqueous solution. Although this indicator cannot be used as an indicator of the concentration of certain oxidizing and reducing substances, it helps to understand the electrochemical characteristics of water bodies and analyze the properties of water bodies; conductivity is a basic electrochemical parameter of an electrolyte solution, and the water content and water purity are measured by conductivity. Temperature, as the name suggests, is the temperature of water quality.

[0004] At present, after the integration of PH, ORP and conductivity monitoring equipment, there is a problem of mutual interference between data, which affects the collection accuracy of various data and the stability of the equipment. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a new type of online water quality monitoring equipment, including a main controller, a power supply module, an RS-485 communication module, a pH signal acquisition module, a conductivity signal acquisition module and an ORP and temperature signal acquisition module; the structures of all the above devices and modules and the connection relationship between them are as follows:

[0006] The main controller is used to collect digital signals of PH, ORP, conductivity and temperature of water quality after analog-to-digital conversion, is responsible for controlling the frequency generator that excites the external impedance when measuring conductivity, and is responsible for interacting and parsing data and commands with the host computer; the RS-485 communication module adopts serial port communication of RS-485 standard interface, and is used for interacting data and commands with the host computer, so as to transmit the collected data to the receiving end;

[0007] The PH signal acquisition module includes a PH electrode probe and a PH signal acquisition circuit; the PH signal acquisition circuit includes an amplifier circuit A, a reference voltage circuit A, a voltage raising circuit A, a first-order low-pass filter circuit A, an analog-to-digital conversion sampling circuit A, a signal isolation circuit A, a power supply isolation circuit A and a linear voltage stabilization circuit A; the PH electrode probe outputs a voltage signal, the signal is amplified by the amplifier circuit A, the output signal of the amplifier circuit A and the reference voltage output by the reference voltage circuit A are converted from negative voltage to positive voltage by the voltage raising circuit A, and then filtered and analog-to-digital conversion sampling circuit A are sequentially passed through the first-order low-pass filter circuit A and the analog-to-digital conversion sampling circuit A, thereby outputting a digital signal corresponding to the PH;

[0008] The ORP and temperature signal acquisition module includes an ORP electrode probe, a temperature sensor and an ORP and temperature signal acquisition circuit; the ORP and temperature signal acquisition circuit includes an amplifier circuit B, a reference voltage circuit B, a voltage raising circuit B, a first-order low-pass filter circuit B, an analog-to-digital conversion sampling circuit B, a signal isolation circuit B, a power supply isolation circuit B, a linear voltage stabilization circuit B and a voltage divider circuit; the ORP electrode probe outputs a voltage signal, the signal is amplified by the amplifier circuit B, the output signal of the amplifier circuit B and the reference voltage output by the reference voltage circuit B, the voltage raising circuit B converts the negative voltage into a positive voltage, and then successively passes through the first-order low-pass filter circuit B and the analog-to-digital conversion sampling circuit B for filtering and analog-to-digital conversion, and then outputs a digital signal corresponding to the ORP; the temperature sensor is a thermistor, and the thermistor is connected in series with an ordinary thin film resistor to form a voltage divider circuit, and the voltage divider circuit is powered by 5V; the analog-to-digital conversion sampling circuit B collects the divided voltage value of the thermistor, calculates the resistance value corresponding to the thermistor through the voltage value, and converts the corresponding temperature through the temperature resistance comparison table;

[0009] The conductivity signal acquisition module includes a conductivity electrode probe, a frequency generator, a voltage follower and a conductivity signal acquisition circuit; the conductivity signal acquisition circuit includes a high-pass filter circuit, an IV conversion circuit, an amplifier circuit C, an analog-to-digital conversion acquisition circuit C; a signal isolation circuit C, a power isolation circuit C and a linear voltage stabilization circuit C;

[0010] The main controller controls the frequency generator to send out an AC signal, the AC signal passes through the high-pass filter circuit and is re-biased, and then the ultra-low impedance operational amplifier is used as a voltage follower for buffering, the signal output by the voltage follower acts on the conductivity electrode probe, and the current signal output by the conductivity electrode probe enters the analog-to-digital conversion acquisition circuit C after passing through the IV conversion circuit and the amplification circuit C, thereby outputting a digital signal corresponding to the conductivity;

[0011] The power supply module includes a power isolation circuit D connected to the power supply, the power supply module supplies power to the system, and is respectively connected to the power isolation circuit A, the power isolation circuit B and the power isolation circuit C, and provides a stable voltage for the pH signal acquisition module, the conductivity signal acquisition module and the ORP and temperature signal acquisition module through the linear voltage stabilizing circuit A, the linear voltage stabilizing circuit B and the linear voltage stabilizing circuit C respectively;

[0012] The RS-485 communication module includes a power isolation circuit E and a signal isolation circuit E connected to the 485 communication circuit;

[0013] The signal isolation circuit A, signal isolation circuit B, signal isolation circuit C, signal isolation circuit E, power isolation circuit D and power isolation circuit E are all connected to the main controller.

[0014] Furthermore, the water quality online monitoring device of the present invention, wherein:

[0015] The signal isolation circuit A, signal isolation circuit B and signal isolation circuit C are respectively connected to the main controller through the IIC bus; the 485 communication circuit is connected to the power isolation circuit E and the signal isolation circuit E through the USART bus.

[0016] The main controller adopts the STM32F103C8T6 chip; the STM32F103C8T6 chip is connected with 5 peripheral filter capacitors, which are respectively recorded as C20, C21, C22, C23, and C24; the C20, C21, C22, C23, and C245 are respectively connected to 3.3V and GND of the STM32F103C8T6 chip; a crystal oscillator Y1 is connected between the OSC_IN pin and the OSC_OUT pin of the STM32F103C8T6 chip, and the OSC_IN pin is grounded through a capacitor C10, and the OSC_OUT pin is grounded through a capacitor C15; the BOOT0 pin of the STM32F103C8T6 chip is grounded after passing through a resistor R5, and the BOOT1 pin is grounded after passing through a resistor R6.

[0017] In the power supply module, the power isolation circuit D adopts an isolated voltage-stabilized DC-DC module, and the isolated voltage-stabilized DC-DC module adopts the URB2405S-6WR3 chip, which is an isolated voltage-stabilized DC-DC single-ended output. The input filter capacitor Cin is connected to Vin and GND of the isolated voltage-stabilized DC-DC; the output filter capacitor Cout is connected to +Vo and 0V of the isolated voltage-stabilized DC-DC.

[0018] The 485 communication circuit includes an isolated RS-485 transceiver, which is an ADM2682EBRIZ chip; the power isolation circuit E and the signal isolation circuit E are integrated inside the ADM2682EBRIZ chip; the ADM2682EBRIZ chip is connected to 8 filter capacitors and pull-up and pull-down resistors, and the 3-pin RxD of the ADM2682EBRIZ chip is connected to the 31-pin USART1_RX of the main controller; the 6-pin TxD of the ADM2682EBRIZ chip is connected to the 30-pin USART1_TX of the main controller; the 4th and 5th pins RE / DE of the ADM2682EBRIZ chip are control pins, which are connected to the 32nd pin of the main controller.

[0019] In the PH signal acquisition circuit, the amplification circuit A includes a pre-stage operational amplifier and two precision operational amplifiers; the pre-stage amplifier uses a high-impedance operational amplifier U1, and the operational amplifier U1 uses a CA3140AE chip. The two precision operational amplifiers are precision operational amplifiers U3 and U5, both of which use OP07CS chips; the reference voltage circuit A uses a reference voltage source U6, and the reference voltage source U6 uses an ADR5040BRTZ chip; the analog-to-digital conversion sampling circuit A uses an analog-to-digital converter U7, and the analog-to-digital converter U7 uses an ADS1115IDGSR chip, and the signal isolation circuit A uses an IIC isolation The IIC isolator U8 adopts the ADuM1250ARZ chip; the power isolation circuit A adopts the isolation voltage stabilizing DC-DC module U20, and the isolation voltage stabilizing DC-DC module U20 adopts the B0505S-1WR3 chip; the linear voltage stabilizing circuit A adopts the linear voltage stabilizing module U19, and the linear voltage stabilizing module U19 adopts the ADP7104ARDZ-5.0 chip; when the pH value is less than 7, the operational amplifier U1 outputs a positive voltage, and when the pH value is greater than 7, the operational amplifier U1 outputs a negative voltage; a zero adjustment circuit composed of a resistor R3 and a resistor R4 is provided between the 1st and 5th pins of the operational amplifier U1 , the circuit output when the input signal is zero is adjusted by the zero adjustment circuit; one end of the resistor R2 is connected in series with one end of the resistor R1, the other end of the resistor R1 is grounded, the other end of the resistor R2 is connected to the 6-pin OUT of the operational amplifier U1, the pin connected to the resistor R2 and the resistor R1 is connected to the 2-pin -IN of the operational amplifier U1, and the amplification factor of the operational amplifier U1 is changed by adjusting the proportional relationship between the resistance values ​​of the resistor R2 and the resistor R1; the signal amplified by the operational amplifier U1 passes through the voltage boosting circuit A composed of the precision operational amplifier U5 and the 5 peripheral resistors connected thereto, and the negative voltage is converted into a positive voltage by the same direction summing method, The resistor R9 and the reference voltage source U6 provide a reference voltage for the voltage boosting circuit A; the signal after passing through the voltage boosting circuit A is filtered by a first-order low-pass filter circuit A composed of a precision operational amplifier U3 and its peripheral resistor-capacitor circuit, and the filtered signal is connected to the analog-to-digital converter U7 of the serial IIC communication interface, the 2-pin SDA1 of the IIC isolator U8 is connected to the 43-pin IIC1_SDA of the main controller, and the 3-pin SCL1 of the IIC isolator U8 is connected to the 42-pin IIC1_SCL of the main controller; communication is performed with the main controller through the IIC isolator U8, and the main controller performs data analysis and processing.

[0020] In the ORP and temperature signal acquisition circuit, the amplifier circuit B includes a pre-stage operational amplifier circuit and two precision operational amplifiers, the pre-stage operational amplifier circuit is a high-impedance operational amplifier U9, and the operational amplifier U9 is a CA3140AE chip; the two precision operational amplifiers are a precision operational amplifier U11 and a precision operational amplifier U10, and the precision operational amplifier U11 and the precision operational amplifier U10 are both OP07CS chips; the reference voltage circuit B uses a reference voltage source U12, and the reference voltage source U12 uses an ADR5040BRTZ chip; the analog-to-digital conversion sampling circuit B uses an analog-to-digital converter U13, and the analog-to-digital converter U13 uses an ADS1115I DGSR chip, the signal isolation circuit B uses IIC isolator U14, and the IIC isolator U14 uses ADuM1250ARZ chip; the thermistor uses NTC thermistor; the power isolation circuit B uses isolation voltage stabilizing DC-DC module U21, and the isolation voltage stabilizing DC-DC module U21 uses B0505S-1WR3 chip; the linear voltage stabilizing circuit B uses linear voltage stabilizing module U22, and the linear voltage stabilizing module U22 uses ADP7104ARDZ-5.0 chip; a zero adjustment circuit composed of resistors R26 and R27 is provided between pins 1 and 5 of the operational amplifier U9, and the circuit output when the input signal is zero is adjusted by the zero adjustment circuit , one end of the resistor R25 and one end of the resistor R24 ​​are connected in series, the other end of the resistor R24 ​​is grounded, the other end of the resistor R25 is connected to the 6-pin OUT of the operational amplifier U9, the pin connected to the resistor R25 and the resistor R24 ​​is connected to the 2-pin -IN of the operational amplifier U9, and the amplification factor of the operational amplifier U9 is changed by adjusting the proportional relationship between the resistance values ​​of the resistor R25 and the resistor R24; the signal amplified by the operational amplifier U9 passes through the voltage boosting circuit B composed of the precision operational amplifier U11 and the 5 peripheral resistors connected thereto, and the negative voltage is converted into a positive voltage by the same direction summing method, and the resistor R37 and the reference voltage source U12 provide a reference voltage for the voltage boosting circuit B; after the signal is amplified by the operational amplifier U9, the voltage boosting circuit B is converted into a positive voltage by the same direction summing method, and the reference voltage is provided for the voltage boosting circuit B by the resistor R37 and the reference voltage source U12; after the signal is amplified by the operational amplifier U9, the voltage boosting circuit B is converted into a positive voltage by the voltage boosting circuit B composed of the precision operational amplifier U11 and the 5 peripheral resistors connected thereto. The signal after the voltage boosting circuit B is filtered by a first-order low-pass filter circuit B composed of a precision operational amplifier U10 and its peripheral resistor-capacitor circuit, and the filtered signal is connected to the analog-to-digital converter U13 of the serial IIC communication interface; an NTC thermistor is used for temperature acquisition, and the divided voltage signal of the thermistor is connected to the analog-to-digital converter U13 through the voltage divider circuit, the 2-pin SDA1 of the IIC isolator U14 is connected to the 22-pin IIC2_SDA of the main controller U2, and the 3-pin SCL1 of the IIC isolator U14 is connected to the 21-pin IIC2_SCL of the main controller U2, and communication is performed with the main controller through the IIC isolator U14, and the main controller performs data analysis and processing.

[0021] In the conductivity signal acquisition module, the frequency generator is selected from the frequency generator integrated in the impedance measurement chip U17, and the impedance measurement chip U17 adopts the AD5933YRSZ chip; the amplification circuit C includes an ultra-low impedance operational amplifier U18 and a precision operational amplifier U16, and the ultra-low impedance operational amplifier U18 adopts the AD820AR chip, and the precision operational amplifier U16 adopts the AD8603AUJ-R2 chip, and the analog-to-digital conversion acquisition circuit is integrated in the impedance measurement chip U17; the signal The isolation circuit C uses an IIC isolator U15, and the IIC isolator U15 uses an ADuM1250ARZ chip; the power isolation circuit C uses an isolation voltage regulator DC-DC module U23, and the isolation voltage regulator DC-DC module U23 uses a B0505S-1WR3 chip; the linear voltage regulator circuit C uses a linear voltage regulator module U24, and the linear voltage regulator module U24 uses an ADP7104ARDZ-5.0 chip; the frequency generator sends an AC signal to excite the water quality impedance, and the AC signal passes through the impedance measurement device. The high-pass filter circuit composed of two capacitors between the impedance measurement chip U17 and the ultra-low impedance operational amplifier U18 is filtered, and re-biased through two peripheral resistors connected to the ultra-low impedance operational amplifier U18, and then the ultra-low impedance operational amplifier U18 is used as a voltage follower for buffering, and the output signal of the voltage follower acts on the conductivity electrode probe, and the current signal output by the conductivity electrode probe is IV converted through the IV conversion circuit composed of the precision operational amplifier U16 and its peripheral resistors and capacitors, and enters the analog-to-digital conversion acquisition circuit C integrated in the impedance measurement chip U17 after passing through the amplification circuit C, and the analog-to-digital conversion acquisition circuit C outputs a digital signal corresponding to the conductivity; the 2-pin SDA1 of the IIC isolator U15 is connected to the 22-pin IIC2_SDA of the main controller, and the 3-pin SCL1 of the IIC isolator U15 is connected to the 21-pin IIC2_SCL of the main controller, and the main controller communicates with the main controller through the IIC isolator U15, and the main controller performs data analysis and processing.

[0022] The B0505S-1WR3 chip is an isolated voltage-stabilized DC-DC single-ended output, the input filter capacitor Cin is connected to the Vin and GND of the isolated voltage-stabilized DC-DC; the output filter capacitor is connected to the +Vo and 0V of the isolated voltage-stabilized DC-DC; the ADP7104ARDZ-5.0 chip is a low-noise, LDO micro-power regulator, and the output filter capacitor is connected to the Vout and GND of the linear regulator.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention can monitor the pH, ORP, conductivity and temperature of water quality online in real time. Compared with the prior art, the device integrates the monitoring parameters of pH, ORP, conductivity and temperature, and effectively solves the mutual interference problem between pH, ORP and conductivity. Each module exists independently, and the data is isolated and communicated, which effectively avoids the interference of the external environment, and at the same time ensures the collection accuracy of various data and the stability of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the system composition of the water quality online monitoring device of the present invention;

[0026] Figure 2 is a circuit diagram of a power supply module in the monitoring device of the present invention;

[0027] Figure 3 It is a circuit diagram of a main controller in the monitoring device of the present invention;

[0028] Figure 4 It is a circuit diagram of the RS-485 communication module in the monitoring device of the present invention;

[0029] Figure 5 It is a circuit diagram of a pH signal acquisition module in the monitoring device of the present invention;

[0030] Figure 6 It is a circuit diagram of the ORP and temperature signal acquisition module in the monitoring device of the present invention;

[0031] Figure 7 It is a circuit diagram of the conductivity signal acquisition module in the monitoring device of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are part of the embodiments of the present invention, rather than all the embodiments.

[0033] like Figure 1 As shown, a novel online water quality monitoring device proposed by the present invention includes a main controller, a power supply module, an RS-485 communication module, a PH signal acquisition module, a conductivity signal acquisition module, and an ORP and temperature signal acquisition module, and each module has isolated communication.

[0034] The main controller is used to collect digital signals of PH, ORP, conductivity and temperature of water quality after analog-to-digital conversion, is responsible for controlling the frequency generator that excites the external impedance when measuring conductivity, and is responsible for interacting and analyzing data and commands with the host computer.

[0035] The RS-485 communication module adopts the serial communication of RS-485 standard interface, and its purpose is to interact with the host computer for data and commands, so as to effectively transmit the collected data to the receiving end.

[0036] The PH signal acquisition module includes a PH electrode probe and a PH signal acquisition circuit; the PH signal acquisition circuit includes an amplifier circuit A, a reference voltage circuit A, a voltage boost circuit A, a first-order low-pass filter circuit A, an analog-to-digital conversion sampling circuit A, a signal isolation circuit A, a power supply isolation circuit A and a linear voltage stabilization circuit A; the PH electrode probe outputs a voltage signal, the signal is amplified by the amplifier circuit A, the output signal of the amplifier circuit A and the reference voltage output by the reference voltage circuit A are converted from negative voltage to positive voltage by the voltage boost circuit A, and then filtered and analog-to-digital conversion sampling circuit A are sequentially passed through the first-order low-pass filter circuit A and the analog-to-digital conversion sampling circuit A, thereby outputting a digital signal corresponding to the PH.

[0037] The ORP and temperature signal acquisition module includes an ORP electrode probe, a temperature sensor and an ORP and temperature signal acquisition circuit; the ORP and temperature signal acquisition circuit includes an amplifier circuit B, a reference voltage circuit B, a voltage raising circuit B, a first-order low-pass filter circuit B, an analog-to-digital conversion sampling circuit B, a signal isolation circuit B, a power supply isolation circuit B, a linear voltage stabilization circuit B and a voltage divider circuit; the ORP electrode probe outputs a voltage signal, the signal is amplified by the amplifier circuit B, the output signal of the amplifier circuit B and the reference voltage output by the reference voltage circuit B, the voltage raising circuit B converts the negative voltage into a positive voltage, and then successively passes through the first-order low-pass filter circuit B and the analog-to-digital conversion sampling circuit B for filtering and analog-to-digital conversion, and then outputs a digital signal corresponding to the ORP; the temperature sensor is a thermistor, and the thermistor is connected in series with an ordinary thin film resistor to form a voltage divider circuit, and the voltage divider circuit is powered by 5V; the analog-to-digital conversion sampling circuit B collects the divided voltage value of the thermistor, calculates the resistance value corresponding to the thermistor through the voltage value, and converts the corresponding temperature through the temperature resistance comparison table.

[0038] The conductivity signal acquisition module includes a conductivity electrode probe, a frequency generator, a voltage follower and a conductivity signal acquisition circuit; the conductivity signal acquisition circuit includes a high-pass filter circuit, an IV conversion circuit, an amplifier circuit C, an analog-to-digital conversion acquisition circuit C; a signal isolation circuit C, a power isolation circuit C and a linear voltage stabilization circuit C.

[0039] The main controller controls the frequency generator to send out an AC signal, which passes through the high-pass filter circuit and is re-biased, and then the ultra-low impedance operational amplifier is used as a voltage follower for buffering. The signal output by the voltage follower acts on the conductivity electrode probe, and the current signal output by the conductivity electrode probe enters the analog-to-digital conversion acquisition circuit C after passing through the IV conversion circuit and the amplification circuit C, thereby outputting a digital signal corresponding to the conductivity.

[0040] The power supply module includes a power isolation circuit D connected to a power supply. The power supply module supplies power to the system and is respectively connected to a power isolation circuit A, a power isolation circuit B and a power isolation circuit C, and provides a stable voltage for the PH signal acquisition module, the conductivity signal acquisition module and the ORP and temperature signal acquisition module through a linear voltage stabilizing circuit A, a linear voltage stabilizing circuit B and a linear voltage stabilizing circuit C respectively.

[0041] In the present invention, the signal isolation circuit A, signal isolation circuit B, signal isolation circuit C, signal isolation circuit E, power isolation circuit D and power isolation circuit E are all connected to the main controller; the signal isolation circuit A, signal isolation circuit B and signal isolation circuit C are respectively connected to the main controller through an IIC bus; the 485 communication circuit is connected to the power isolation circuit E and the signal isolation circuit E through a USART bus.

[0042] like Figure 2 As shown, in the power supply module, the power supply module isolates the DC-DC to provide power for the entire system. The power isolation circuit D in the power supply module adopts an isolated voltage-stabilized DC-DC module, and the isolated voltage-stabilized DC-DC module adopts the URB2405S-6WR3 chip, which is an isolated voltage-stabilized DC-DC single-ended output. The input filter capacitor Cin is connected to Vin and GND of the isolated voltage-stabilized DC-DC; the output filter capacitor Cout is connected to +Vo and 0V of the isolated voltage-stabilized DC-DC.

[0043] like Figure 3As shown, the main controller U2 of the main controller module in the present invention serves as the core controller of the system, and it adopts the STM32F103C8T6 chip; the STM32F103C8T6 chip is connected with 5 peripheral filter capacitors, which are respectively recorded as C20, C21, C22, C23, and C24; the C20, C21, C22, C23, and C245 are respectively connected to 3.3V and GND of the STM32F103C8T6 chip; a crystal oscillator Y1 is connected between the OSC_IN pin and the OSC_OUT pin of the STM32F103C8T6 chip, and the OSC_IN pin is grounded through a capacitor C10, and the OSC_OUT pin is grounded through a capacitor C15; the BOOT0 pin of the STM32F103C8T6 chip is grounded after passing through a resistor R5, and the BOOT1 pin is grounded after passing through a resistor R6, and resistors R5 and R6 are gate resistors for the main controller working mode.

[0044] like Figure 4 As shown, the RS-485 communication module includes a power isolation circuit E and a signal isolation circuit E connected to the 485 communication circuit. The 485 communication circuit includes an isolated RS-485 transceiver, which is an ADM2682EBRIZ chip; the power isolation circuit E and the signal isolation circuit E are integrated inside the ADM2682EBRIZ chip; the ADM2682EBRIZ chip is connected to 8 filter capacitors (capacitors C11, C12, C13, C14, C16, C17, C18, C19) and pull-up and pull-down resistors R8 and R9, and the 3-pin RxD of the ADM2682EBRIZ chip is connected to the 31-pin USART1_RX of the main controller; the 6-pin TxD of the ADM2682EBRIZ chip is connected to the 30-pin USART1_TX of the main controller; the 4- and 5-pin RE / DE of the ADM2682EBRIZ chip are control pins, connected to the 32-pin of the main controller.

[0045] like Figure 5 As shown, in the PH signal acquisition circuit of the PH signal acquisition module, the amplification circuit A includes a pre-stage operational amplifier and two precision operational amplifiers; the pre-stage amplifier uses a high-impedance operational amplifier U1, and the operational amplifier U1 uses a CA3140AE chip. The two precision operational amplifiers are precision operational amplifiers U3 and U5, both of which use OP07CS chips.

[0046] The reference voltage circuit A uses a reference voltage source U6, and the reference voltage source U6 adopts an ADR5040BRTZ chip; the analog-to-digital conversion sampling circuit A uses an analog-to-digital converter U7, and the analog-to-digital converter U7 adopts an ADS1115IDGSR chip; the signal isolation circuit A uses an IIC isolator U8, and the IIC isolator U8 adopts an ADuM1250ARZ chip; the power isolation circuit A uses an isolated voltage stabilizing DC-DC module U20, and the isolated voltage stabilizing DC-DC module U20 adopts a B0505S-1WR3 chip; the linear voltage stabilizing circuit A uses a linear voltage stabilizing module U19, and the linear voltage stabilizing module U19 adopts an ADP7104ARDZ-5.0 chip.

[0047] The isolated voltage-stabilized DC-DC module U20, the voltage input filter capacitors C30 and C32, and the voltage output filter capacitors C31 and C33 form a power isolation circuit A to provide isolated power for the PH signal acquisition module. The linear voltage regulator module U19, the control power supply on-off resistor R56, and the voltage output filter capacitors C28 and C29 form a linear voltage regulator circuit A to provide a stable, low-noise linear voltage for the PH signal acquisition module. The PH electrode probe is actually a high-impedance millivoltmeter. Since the impedance of the PH electrode is particularly large, the high-impedance operational amplifier U1 is used in the circuit design for the pre-stage operational amplifier circuit of the PH signal detection circuit. Due to the different measured PH values, the output voltage of the PH electrode is positive or negative.

[0048] When the pH value is less than 7, the output of the operational amplifier U1 is a positive voltage, and when the pH value is greater than 7, the output of the operational amplifier U1 is a negative voltage; a zero adjustment circuit composed of resistors R3 and R4 is provided between pins 1 and 5 of the operational amplifier U1, and the circuit output when the input signal is zero is adjusted by the zero adjustment circuit; one end of the resistor R2 is connected in series with one end of the resistor R1, the other end of the resistor R1 is grounded, the other end of the resistor R2 is connected to the 6-pin OUT of the operational amplifier U1, and the pin connected to the resistor R2 and the resistor R1 is connected to the 2 Pin -IN, by adjusting the proportional relationship between the resistance values ​​of resistor R2 and resistor R1, the amplification factor of the operational amplifier U1 can be changed; since the selected analog-to-digital conversion chip U7 cannot collect negative voltage, the signal amplified by the operational amplifier U1 needs to pass through the voltage boosting circuit A composed of the precision operational amplifier U5 and the 5 peripheral resistors (resistors R11, R13, R16, R17, R18) connected thereto, and the negative voltage is converted into a positive voltage through the same direction summation method, and the resistor R9 and the reference voltage source U6 provide the reference voltage for the voltage boosting circuit A. The signal after passing through the voltage raising circuit A is filtered by a first-order low-pass filter circuit A composed of a precision operational amplifier U3 and its peripheral resistor-capacitor (three resistors R10, R12, R15 and a capacitor C1) circuit, and the filtered signal is connected to the analog-to-digital converter U7 of the serial IIC communication interface, the 2-pin SDA1 of the IIC isolator U8 is connected to the 43-pin IIC1_SDA of the main controller, and the 3-pin SCL1 of the IIC isolator U8 is connected to the 42-pin IIC1_SCL of the main controller U2; communication is performed with the main controller through the IIC isolator U8, and the main controller performs data analysis and processing.

[0049] like Figure 6 As shown, in the ORP and temperature signal acquisition circuit of the ORP and temperature signal acquisition module, the amplification circuit B includes a pre-stage operational amplifier circuit and two precision operational amplifiers, the pre-stage operational amplifier circuit is a high-impedance operational amplifier U9, and the operational amplifier U9 is a CA3140AE chip; the two precision operational amplifiers are respectively a precision operational amplifier U11 and a precision operational amplifier U10, and the precision operational amplifier U11 and the precision operational amplifier U10 are both OP07CS chips; the reference voltage circuit B uses a reference voltage source U12, and the reference voltage source U12 uses an ADR5040BRTZ chip; the analog-to-digital conversion sampling circuit B uses an analog-to-digital converter U13, and the analog-to-digital converter U13 uses an ADS1115IDGSR chip; the signal isolation circuit B uses an IIC isolator U14, and the IIC isolator U14 uses an ADuM1250ARZ chip; the thermistor uses an NTC thermistor.

[0050] The power isolation circuit B adopts an isolated voltage stabilizing DC-DC module U21, and the isolated voltage stabilizing DC-DC module U21 adopts a B0505S-1WR3 chip; the linear voltage stabilizing circuit B adopts a linear voltage stabilizing module U22, and the linear voltage stabilizing module U22 adopts an ADP7104ARDZ-5.0 chip.

[0051] The isolated voltage-stabilized DC-DC module U21, the voltage input filter capacitors C35 and C37, and the voltage output filter capacitors C36 and C38 form a power isolation circuit B, which provides isolated power for the ORP and temperature signal acquisition modules. The linear voltage-stabilized module U22, the control power supply on-off resistor R57, and the voltage output filter capacitors C34 and C39 form a linear voltage-stabilized circuit B, which provides a stable, low-noise linear voltage for the ORP and temperature signal acquisition modules. The ORP electrode probe is actually a high-impedance millivoltmeter. Since the impedance of the ORP electrode is particularly large, the high-impedance operational amplifier U9 is used in the circuit design for the pre-stage operational amplifier circuit of the ORP signal detection circuit. Since the output voltage of the PH electrode is positive or negative, a zero adjustment circuit is added between pins 1 and 5 of the operational amplifier U9. One end of the resistor R25 and one end of the resistor R24 ​​are connected in series, and the other end of the resistor R24 ​​is grounded. The other end of the resistor R25 is connected to the 6-pin OUT of the operational amplifier U9, and the pin where the resistor R25 and the resistor R24 ​​are connected is connected to the 2-pin -IN of the operational amplifier U9. The amplification factor of the operational amplifier U9 is changed by adjusting the proportional relationship between the resistance values ​​of the resistor R25 and the resistor R24. Since the selected analog-to-digital conversion chip U13 cannot collect negative voltage, the signal amplified by the operational amplifier U9 passes through the voltage boosting circuit B composed of the precision operational amplifier U11 and the five peripheral resistors (resistors R29, R31, R34, R35, and R36) connected thereto, and the negative voltage is converted into a positive voltage through the same direction summing method. The resistor R37 and the reference voltage source U12 provide the reference voltage for the voltage boosting circuit B; the signal after passing through the voltage boosting circuit B passes through the precision operational amplifier U10 and its peripheral resistors and capacitors (three resistors R28, R30, and R33 and one capacitor C3) to convert the negative voltage into a positive voltage. The first-order low-pass filter circuit B composed of the circuit is used for filtering, and the filtered signal is connected to the analog-to-digital converter U13 of the serial IIC communication interface; an NTC thermistor is used for temperature acquisition, and the divided voltage signal of the thermistor is connected to the analog-to-digital converter U13 through the voltage divider circuit, the 2-pin SDA1 of the IIC isolator U14 is connected to the 22-pin IIC2_SDA of the main controller U2, the 3-pin SCL1 of the IIC isolator U14 is connected to the 21-pin IIC2_SCL of the main controller U2, and communication is performed with the main controller through the IIC isolator U14, and the main controller performs data analysis and processing.

[0052] like Figure 7As shown, in the conductivity signal acquisition module, the frequency generator is selected from the frequency generator integrated in the impedance measurement chip U17, and the impedance measurement chip U17 adopts the AD5933YRSZ chip; the amplification circuit C includes an ultra-low impedance operational amplifier U18 and a precision operational amplifier U16, the ultra-low impedance operational amplifier U18 adopts the AD820AR chip, the precision operational amplifier U16 adopts the AD8603AUJ-R2 chip, and the analog-to-digital conversion acquisition circuit is integrated in the impedance measurement chip U17; the signal isolation circuit C selects the IIC isolator U15, and the IIC isolator U15 adopts the ADuM1250ARZ chip; the power isolation circuit C adopts the isolation voltage stabilizing DC-DC module U23, and the isolation voltage stabilizing DC-DC module U23 adopts the B0505S-1WR3 chip; the linear voltage stabilizing circuit C adopts the linear voltage stabilizing module U24, and the linear voltage stabilizing module U24 adopts the ADP7104ARDZ-5.0 chip.

[0053] The isolated voltage-stabilized DC-DC module U23, the voltage input filter capacitors C41 and C43, and the voltage output filter capacitors C42 and C44 form a power isolation circuit C to provide isolated power for the conductivity signal acquisition module. The linear voltage-stabilized module U24, the control power supply on-off resistor R58, and the voltage output filter capacitors C40 and C45 form a linear voltage-stabilized circuit C to provide a stable, low-noise linear voltage for the conductivity signal acquisition module. To measure the water conductivity, the frequency generator integrated in the impedance measurement chip U17 is used to send an AC signal to excite the water impedance, and a suitable excitation frequency is selected. The AC signal is filtered by a high-pass filter circuit composed of C9 and C25, and re-biased by R53 and R55. Then, an ultra-low impedance operational amplifier U18 is used as a voltage follower for buffering. The output signal of the voltage follower acts on the conductivity electrode probe. The current signal output by the conductivity electrode probe is converted by an IV conversion circuit composed of a precision operational amplifier U16 and its peripheral resistors and capacitors. After passing through the amplifier circuit C, it enters the analog-to-digital conversion acquisition circuit C integrated in the impedance measurement chip U17. The analog-to-digital conversion acquisition circuit C outputs a digital signal corresponding to the conductivity. The main controller communicates with the main controller through the IIC isolator U15, and the main controller performs data analysis and processing. The 2-pin SDA1 of the IIC isolator U15 is connected to the 22-pin IIC2_SDA of the main controller U2, and the 3-pin SCL1 of the IIC isolator U15 is connected to the 21-pin IIC2_SCL of the main controller U2.

[0054] like Figure 5 , Figure 6 and Figure 7As shown, in the present invention, the B0505S-1WR3 chip is an isolated voltage-stabilized DC-DC single-ended output, the input filter capacitor Cin is connected to the Vin and GND of the isolated voltage-stabilized DC-DC; the output filter capacitor is connected to the +Vo and 0V of the isolated voltage-stabilized DC-DC; the ADP7104ARDZ-5.0 chip is a low-noise, LDO micro-power regulator, and the output filter capacitor is connected to the Vout and GND of the linear regulator.

[0055] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can make many modifications without departing from the purpose of the present invention, all of which are within the protection of the present invention.

Claims

1. A water quality online monitoring device, comprising a main controller, a power supply module, an RS-485 communication module, a pH signal acquisition module, a conductivity signal acquisition module, and an ORP and temperature signal acquisition module; characterized in that: The main controller is used to collect digital signals of PH, ORP, conductivity and temperature of water quality after analog-to-digital conversion, is responsible for controlling the frequency generator for testing conductivity, and is responsible for interacting and parsing data and commands with the host computer; the RS-485 communication module adopts serial port communication of RS-485 standard interface, and is used for interacting data and commands with the host computer, thereby transmitting the collected data to the receiving end; The PH signal acquisition module includes a PH electrode probe and a PH signal acquisition circuit; the PH signal acquisition circuit includes an amplifier circuit A, a reference voltage circuit A, a voltage raising circuit A, a first-order low-pass filter circuit A, an analog-to-digital conversion sampling circuit A, a signal isolation circuit A, a power supply isolation circuit A and a linear voltage stabilization circuit A; the PH electrode probe outputs a voltage signal, the signal is amplified by the amplifier circuit A, the output signal of the amplifier circuit A and the reference voltage output by the reference voltage circuit A are converted from negative voltage to positive voltage by the voltage raising circuit A, and then filtered and analog-to-digital conversion sampling circuit A are sequentially passed through the first-order low-pass filter circuit A and the analog-to-digital conversion sampling circuit A, thereby outputting a digital signal corresponding to the PH; The ORP and temperature signal acquisition module includes an ORP electrode probe, a temperature sensor and an ORP and temperature signal acquisition circuit; the ORP and temperature signal acquisition circuit includes an amplifier circuit B, a reference voltage circuit B, a voltage raising circuit B, a first-order low-pass filter circuit B, an analog-to-digital conversion sampling circuit B, a signal isolation circuit B, a power supply isolation circuit B, a linear voltage stabilization circuit B and a voltage divider circuit; the ORP electrode probe outputs a voltage signal, the signal is amplified by the amplifier circuit B, the output signal of the amplifier circuit B and the reference voltage output by the reference voltage circuit B, the voltage raising circuit B converts the negative voltage into a positive voltage, and then successively passes through the first-order low-pass filter circuit B and the analog-to-digital conversion sampling circuit B for filtering and analog-to-digital conversion, and then outputs a digital signal corresponding to the ORP; the temperature sensor is a thermistor, and the thermistor is connected in series with an ordinary thin film resistor to form a voltage divider circuit, and the voltage divider circuit is powered by 5V; the analog-to-digital conversion sampling circuit B collects the divided voltage value of the thermistor, calculates the resistance value corresponding to the thermistor through the voltage value, and converts the corresponding temperature through the temperature resistance comparison table; The conductivity signal acquisition module includes a conductivity electrode probe, a frequency generator, a voltage follower and a conductivity signal acquisition circuit; the conductivity signal acquisition circuit includes a high-pass filter circuit, an IV conversion circuit, an amplifier circuit C, an analog-to-digital conversion acquisition circuit C; a signal isolation circuit C, a power isolation circuit C and a linear voltage stabilization circuit C; The main controller controls the frequency generator to send out an AC signal, and the AC signal passes through the high-pass filter circuit and is re-biased, and then is buffered by using an ultra-low impedance operational amplifier as a voltage follower, and the signal output by the voltage follower acts on the conductivity electrode probe, and the current signal output by the conductivity electrode probe enters the analog-to-digital conversion acquisition circuit C after passing through the IV conversion circuit and the amplification circuit C, thereby outputting a digital signal corresponding to the conductivity; The power supply module includes a power isolation circuit D connected to the power supply, the power supply module supplies power to the system, and is respectively connected to the power isolation circuit A, the power isolation circuit B and the power isolation circuit C, and provides a stable voltage for the pH signal acquisition module, the conductivity signal acquisition module and the ORP and temperature signal acquisition module through the linear voltage stabilizing circuit A, the linear voltage stabilizing circuit B and the linear voltage stabilizing circuit C respectively; The RS-485 communication module includes a power isolation circuit E and a signal isolation circuit E connected to the 485 communication circuit; The signal isolation circuit A, signal isolation circuit B, signal isolation circuit C, signal isolation circuit E, power isolation circuit D and power isolation circuit E are all connected to the main controller.

2. The water quality online monitoring device according to claim 1, characterized in that: The signal isolation circuit A, signal isolation circuit B and signal isolation circuit C are respectively connected to the main controller through the IIC bus; the 485 communication circuit is connected to the power isolation circuit E and the signal isolation circuit E through the USART bus.

3. The water quality online monitoring device according to claim 1, characterized in that: The main controller adopts STM32F103C8T6 chip; The STM32F103C8T6 chip is connected with 5 peripheral filter capacitors, which are respectively recorded as C20, C21, C22, C23, and C24; the C20, C21, C22, C23, and C245 are respectively connected to 3.3V and GND of the STM32F103C8T6 chip; A crystal oscillator Y1 is connected between the OSC_IN pin and the OSC_OUT pin of the STM32F103C8T6 chip, and the OSC_IN pin is grounded through a capacitor C10, and the OSC_OUT pin is grounded through a capacitor C15; The BOOT0 pin of the STM32F103C8T6 chip is grounded through a resistor R5, and the BOOT1 pin is grounded through a resistor R6.

4. The water quality online monitoring device according to claim 1, characterized in that: In the power supply module, the power isolation circuit D adopts an isolated voltage-stabilized DC-DC module, and the isolated voltage-stabilized DC-DC module adopts the URB2405S-6WR3 chip, which is an isolated voltage-stabilized DC-DC single-ended output. The input filter capacitor Cin is connected to Vin and GND of the isolated voltage-stabilized DC-DC; the output filter capacitor Cout is connected to +Vo and 0V of the isolated voltage-stabilized DC-DC.

5. The water quality online monitoring device according to claim 1, characterized in that: The 485 communication circuit includes an isolated RS-485 transceiver, which is an ADM2682EBRIZ chip; the power isolation circuit E and the signal isolation circuit E are integrated inside the ADM2682EBRIZ chip; the ADM2682EBRIZ chip is connected to 8 filter capacitors and pull-up and pull-down resistors, and the 3-pin RxD of the ADM2682EBRIZ chip is connected to the 31-pin USART1_RX of the main controller; the 6-pin TxD of the ADM2682EBRIZ chip is connected to the 30-pin USART1_TX of the main controller; the 4th and 5th pins RE / DE of the ADM2682EBRIZ chip are control pins, which are connected to the 32-pin of the main controller.

6. The water quality online monitoring device according to claim 1, characterized in that: In the PH signal acquisition circuit, The amplifier circuit A includes a pre-stage operational amplifier and two precision operational amplifiers; the pre-stage operational amplifier uses a high-impedance operational amplifier U1, and the operational amplifier U1 uses a CA3140AE chip. The two precision operational amplifiers are precision operational amplifiers U3 and U5, both of which use OP07CS chips; The reference voltage circuit A uses a reference voltage source U6, and the reference voltage source U6 uses an ADR5040BRTZ chip; the analog-to-digital conversion sampling circuit A uses an analog-to-digital converter U7, and the analog-to-digital converter U7 uses an ADS1115IDGSR chip; the signal isolation circuit A uses an IIC isolator U8, and the IIC isolator U8 uses an ADuM1250ARZ chip; the power isolation circuit A uses an isolated voltage stabilizing DC-DC module U20, and the isolated voltage stabilizing DC-DC module U20 uses a B0505S-1WR3 chip; the linear voltage stabilizing circuit A uses a linear voltage stabilizing module U19, and the linear voltage stabilizing module U19 uses an ADP7104ARDZ-5.0 chip; When the PH value is less than 7, the output of the operational amplifier U1 is a positive voltage, and when the PH value is greater than 7, the output of the operational amplifier U1 is a negative voltage; a zero adjustment circuit composed of resistors R3 and R4 is provided between pins 1 and 5 of the operational amplifier U1, and the circuit output when the input signal is zero is adjusted by the zero adjustment circuit; one end of the resistor R2 is connected in series with one end of the resistor R1, the other end of the resistor R1 is grounded, the other end of the resistor R2 is connected to the 6-pin OUT of the operational amplifier U1, and the pin connected to the resistor R2 and the resistor R1 is connected to the 2-pin -IN of the operational amplifier U1, and the amplification factor of the operational amplifier U1 is changed by adjusting the proportional relationship between the resistance values ​​of the resistors R2 and R1; the signal amplified by the operational amplifier U1 passes through a voltage boosting circuit A composed of a precision operational amplifier U5 and 5 peripheral resistors connected thereto, and the negative voltage is converted into a positive voltage by a method of summing in the same direction, and the resistor R9 and the reference voltage source U6 provide a reference voltage for the voltage boosting circuit A; The signal after passing through the voltage boosting circuit A is filtered by a first-order low-pass filter circuit A composed of a precision operational amplifier U3 and its peripheral resistor-capacitor circuit. The filtered signal is connected to the analog-to-digital converter U7 of the serial IIC communication interface. The 2-pin SDA1 of the IIC isolator U8 is connected to the 43-pin IIC1_SDA of the main controller U2, and the 3-pin SCL1 of the IIC isolator U8 is connected to the 42-pin IIC1_SCL of the main controller U2. Communication is performed with the main controller through the IIC isolator U8, and the main controller performs data analysis and processing.

7. The water quality online monitoring device according to claim 1, characterized in that: In the ORP and temperature signal acquisition circuit, The amplifier circuit B includes a pre-stage operational amplifier circuit and two precision operational amplifiers, wherein the pre-stage operational amplifier circuit is a high-impedance operational amplifier U9, and the operational amplifier U9 is a CA3140AE chip; the two precision operational amplifiers are respectively a precision operational amplifier U11 and a precision operational amplifier U10, and both the precision operational amplifier U11 and the precision operational amplifier U10 are OP07CS chips; the reference voltage circuit B uses a reference voltage source U12, and the reference voltage source U12 uses an ADR5040BRTZ chip; the analog-to-digital conversion sampling circuit B uses an analog-to-digital converter U13, and the analog-to-digital converter U13 uses an ADS1115IDGSR chip; the signal isolation circuit B uses an IIC isolator U14, and the IIC isolator U14 uses an ADuM1250ARZ chip; the thermistor uses an NTC thermistor; The power isolation circuit B adopts an isolated voltage stabilizing DC-DC module U21, and the isolated voltage stabilizing DC-DC module U21 adopts a B0505S-1WR3 chip; the linear voltage stabilizing circuit B adopts a linear voltage stabilizing module U22, and the linear voltage stabilizing module U22 adopts an ADP7104ARDZ-5.0 chip; A zero adjustment circuit composed of a resistor R26 and a resistor R27 is provided between pins 1 and 5 of the operational amplifier U9, and the circuit output when the input signal is zero is adjusted by the zero adjustment circuit. One end of the resistor R25 is connected in series with one end of the resistor R24, and the other end of the resistor R24 ​​is grounded. The other end of the resistor R25 is connected to the 6-pin OUT of the operational amplifier U9, and the pin connected to the resistor R25 and the resistor R24 ​​is connected to the 2-pin -IN of the operational amplifier U9. The amplification factor of the operational amplifier U9 is changed by adjusting the proportional relationship between the resistance values ​​of the resistor R25 and the resistor R24. The signal amplified by the operational amplifier U9 passes through a voltage boosting circuit B composed of a precision operational amplifier U11 and 5 peripheral resistors connected thereto, and the negative voltage is converted into a positive voltage by a method of summing in the same direction, and the resistor R37 and the reference voltage source U12 provide a reference voltage for the voltage boosting circuit B. The signal after passing through the voltage boosting circuit B is filtered by a first-order low-pass filter circuit B composed of a precision operational amplifier U10 and its peripheral resistor-capacitor circuit, and the filtered signal is connected to the analog-to-digital converter U13 of the serial IIC communication interface; an NTC thermistor is used for temperature acquisition, and the divided voltage signal of the thermistor is connected to the analog-to-digital converter U13 through the voltage divider circuit, the 2-pin SDA1 of the IIC isolator U14 is connected to the 22-pin IIC2_SDA of the main controller U2, the 3-pin SCL1 of the IIC isolator U14 is connected to the 21-pin IIC2_SCL of the main controller U2, and communication is performed with the main controller through the IIC isolator U14, and the main controller performs data analysis and processing.

8. The water quality online monitoring device according to claim 1, characterized in that: In the conductivity signal acquisition module, The frequency generator uses the frequency generator integrated in the impedance measurement chip U17, and the impedance measurement chip U17 uses the AD5933YRSZ chip; the amplification circuit C includes an ultra-low impedance operational amplifier U18 and a precision operational amplifier U16, and the ultra-low impedance operational amplifier U18 uses the AD820AR chip, and the precision operational amplifier U16 uses the AD8603AUJ-R2 chip, and the analog-to-digital conversion acquisition circuit is integrated in the impedance measurement chip U17; the signal isolation circuit C uses the IIC isolator U15, and the IIC isolator U15 uses the ADuM1250ARZ chip; the power isolation circuit C uses the isolation voltage regulator DC-DC module U23, and the isolation voltage regulator DC-DC module U23 uses the B0505S-1WR3 chip; the linear voltage regulator circuit C uses the linear voltage regulator module U24, and the linear voltage regulator module U24 uses the ADP7104ARDZ-5.0 chip; The frequency generator sends out an AC signal to stimulate the water quality impedance. The AC signal is filtered by the high-pass filter circuit composed of two capacitors arranged between the impedance measurement chip U17 and the ultra-low impedance operational amplifier U18, and is re-biased by two peripheral resistors connected to the ultra-low impedance operational amplifier U18. The ultra-low impedance operational amplifier U18 is then used as a voltage follower for buffering. The output signal of the voltage follower acts on the conductivity electrode probe. The current signal output by the conductivity electrode probe passes through the precision operational amplifier U16 and its external The IV conversion circuit composed of a resistor and a capacitor performs IV conversion, and after passing through the amplifier circuit C, enters the analog-to-digital conversion acquisition circuit C integrated in the impedance measurement chip U17, and the analog-to-digital conversion acquisition circuit C outputs a digital signal corresponding to the conductivity; the 2-pin SDA1 of the IIC isolator U15 is connected to the 22-pin IIC2_SDA of the main controller, and the 3-pin SCL1 of the IIC isolator U15 is connected to the 21-pin IIC2_SCL of the main controller, and the main controller communicates with the main controller through the IIC isolator U15, and the main controller performs data analysis and processing.

9. The water quality online monitoring device according to any one of claims 6 to 8, characterized in that: The B0505S-1WR3 chip is an isolated voltage-stabilized DC-DC single-ended output, the input filter capacitor Cin is connected to the Vin and GND of the isolated voltage-stabilized DC-DC; the output filter capacitor is connected to the +Vo and 0V of the isolated voltage-stabilized DC-DC; the ADP7104ARDZ-5.0 chip is a low-noise, LDO micro-power regulator, and the output filter capacitor is connected to the Vout and GND of the linear regulator.

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