A Dialysis Fluid Conductivity Monitoring System

Abstract

This invention provides a dialysate conductivity monitoring system, relating to the field of circuit design technology. It includes a signal input module, an MCU module, a communication module, a voltage regulator module, a data isolation module, a data conversion module, and a temperature measurement module. The signal input module generates a reference signal for conductivity detection and an input signal for the detection head. The voltage regulator module provides a stable voltage. The temperature measurement module measures the temperature of the standard solution. The data isolation module achieves communication data isolation, and the data conversion module converts the output data. The circuit automatically adapts to the inner diameter of the carbon ring and isolation column, resulting in very small measurement errors. It features built-in carbon ring and isolation column calcium deposit detection for easier and simpler maintenance. The output signal uses MCU closed-loop control, with adjustable signal amplitude, automatic matching and calibration of the conductivity head, and CAN communication for easier debugging.

Description

Technical Field

[0001] The invention relates to the technical field of circuit design, and in particular to a dialysate conductivity monitoring system. Background Art

[0002] Conductivity is a parameter used to describe the ease with which electric charges flow in a substance. Conductivity is represented by the Greek letter σ. The standard unit of conductivity σ is Siemens / meter (abbreviated as S / m), which is the reciprocal of resistivity ρ, that is, σ = 1 / ρ.

[0003] The existing measurement system cannot be flexibly adapted due to the fixed input signal amplitude and frequency, resulting in many circuits not being able to adapt to the inner diameter of the carbon ring and the isolation column. The processing errors of the inner diameter of the carbon ring and the isolation column will cause large measurement errors, making the measurement system inaccurate and very difficult to maintain. Summary of the invention

[0004] The present invention aims to provide a dialysate conductivity monitoring system to solve the above technical problems. The circuit automatically adapts to the inner diameter of the carbon ring and the isolation column, and the measurement error is very small. It has its own carbon ring and isolation column calcium detection function, which makes maintenance more convenient and simple. The output signal adopts MCU closed-loop control, the signal amplitude is adjustable, and the conductivity head is automatically matched and automatically corrected.

[0005] In order to solve the above technical problems, the present invention provides a dialysate conductivity monitoring system, including a signal input module, an MCU module, a communication module, a voltage stabilization module, a data isolation module, a data conversion module, and a temperature measurement module;

[0006] The output end of the signal input module, the output end of the voltage stabilization module and the output end of the temperature measurement module are electrically connected to the input end of the MCU module, and the data isolation module, the data conversion module and the communication module are all electrically connected to the MCU module in a bidirectional manner;

[0007] The signal input module is used to generate the reference signal for conductivity detection and the input signal of the detection head; the voltage stabilization module is used to provide a stable voltage; the temperature measurement module is used to measure the temperature value of the standard liquid; the MCU module is used for data processing; the communication module is used to realize data interaction; the data isolation module is used to realize communication data isolation, and the data conversion module is used to convert output data.

[0008] In the above scheme, the circuit automatically adapts to the inner diameter of the carbon ring and the isolation column, and the measurement error is very small. It has its own calcium detection function for the carbon ring and the isolation column, which makes maintenance more convenient and simple. The output signal adopts MCU closed-loop control, the signal amplitude is adjustable, and the conductivity head is automatically matched and automatically corrected. CAN communication is adopted, which makes debugging more convenient.

[0009] The MCU module generates a sine wave with adjustable output frequency and amplitude as the reference signal for conductivity detection through digital-to-analog conversion. The MCU module outputs a DC voltage that is superimposed on the reference voltage as the input signal of the detection head. After the signal passes through the liquid flowing in the carbon ring and isolation column assembly, the signal will be reduced due to the internal resistance of the liquid. The final signal will be input to the operational amplifier. After amplification and limiting filtering by the operational amplifier, the final output signal will output a DC voltage after passing through the RC filter circuit. After ADC conversion, the MCU converts the DC voltage into a digital quantity and sends it out through the CAN bus. The MCU module outputs a DC superimposed signal to correct the unequal positive and negative amplitudes of the sine wave, thereby achieving more accurate conductivity detection errors.

[0010] The other signal is used as a calcium deposition detection signal. After amplification, limiting and filtering, it is sent to the MCU to realize the self-check function of whether calcium deposition occurs, which greatly facilitates the maintenance of the conductivity component. The principle of calcium deposition detection is that after the conductivity component is calibrated, the MCU output waveform is fixed, and the voltage value after the standard solution passes through is read. By comparing the voltage value, it can be found whether there is a deviation inside the conductivity. At the same time, the values ​​of ADC1 and ADC2 are compared, and then the change of the inner diameter is calculated. If there is an error, it is considered that calcium deposition has occurred inside.

[0011] Preferably, the signal input module includes several operational amplifiers. The sine wave output by the MCU module passes through a follower composed of operational amplifiers, and is combined with another signal using an adder to finally output a signal to an external conductivity head; both signals are input into the operational amplifier after passing through the conductivity head for detection and inversion amplification, and are amplified again by the operational amplifier after filtering to obtain a DC voltage input into the MCU module for processing; wherein, the number of amplification levels of the operational amplifier for the first time is greater than the number of amplification levels for the second time.

[0012] Preferably, the signal input module includes capacitors C1 to C10, resistors R1 to R23, diodes D1 to D4, operational amplifiers U1 to U8 and 5 plug-in connectors; specifically:

[0013] The MCU module is electrically connected to the in-phase input terminal of the operational amplifier U1 through the resistor R1, and the output terminal of the operational amplifier U1 is electrically connected to the inverting input terminal of the operational amplifier U1 and one end of the resistor R2; the positive and negative electrodes of the operational amplifier U1 are both connected to a 5V voltage and are grounded through capacitors C1 and C2 respectively; the other end of the resistor R2 is electrically connected to the inverting input terminal of the operational amplifier U2, the MCU module is electrically connected to the in-phase input terminal of the operational amplifier U2 through the resistor R3, and the in-phase input terminal of the operational amplifier U2 is grounded through the resistor R4, the output terminal of the operational amplifier U2 is electrically connected to the inverting input terminal of the operational amplifier U2 through the resistor R5, and is connected to the 4 pins of the 5 plug-in connector;

[0014] Pin 2 of the 5-pin connector is electrically connected to the non-inverting input terminal of the operational amplifier U3 through the resistor R6, and is electrically connected to the inverting input terminal of the operational amplifier U4; the output terminal of the operational amplifier U3 is electrically connected to the inverting input terminal of the operational amplifier U4 through the capacitor C3 and the resistor R7 in sequence, and is electrically connected to the inverting input terminal of the operational amplifier U3, the positive and negative electrodes of the operational amplifier U3 are both connected to a 5V voltage, and are grounded through the capacitor C4 and the capacitor C5 respectively; the non-inverting input terminal of the operational amplifier U4 is grounded through the resistor R16, the output terminal of the operational amplifier U4 is electrically connected to the input terminal of the diode D1 and the output terminal of the diode D2 respectively, the output terminal of the diode D1 is electrically connected to the inverting input terminal of the operational amplifier U4, and the two The input end of the diode D2 is electrically connected to one end of the resistor R8 and one end of the resistor R9, and the other end of the resistor R8 is electrically connected to the inverting input end of the operational amplifier U4; the other end of the resistor R9 is grounded through the capacitor C6 and is electrically connected to one end of the resistor R10; the other end of the resistor R10 is electrically connected to the inverting input end of the operational amplifier U5, and the non-inverting input end of the operational amplifier U5 is grounded through the resistor R12; the output end of the operational amplifier U5 is electrically connected to the inverting input end of the operational amplifier U5 through the resistor R11, and is electrically connected to one end of the resistor R13; the other end of the resistor R13 is grounded through the capacitor C7, and is electrically connected to one end of the resistor R14, and the other end of the resistor R14 is electrically connected to the MCU module;

[0015] Pin 3 of the 5-pin connector is electrically connected to the non-inverting input terminal of the operational amplifier U6 through the resistor R15; the output terminal of the operational amplifier U6 is electrically connected to the inverting input terminal of the operational amplifier U6, and is electrically connected to the inverting input terminal of the operational amplifier U7 through the capacitor C8 and the resistor R19 in sequence; the non-inverting input terminal of the operational amplifier U7 is electrically connected to the output terminal of the diode D3 and the input terminal of the diode D4 respectively; the output terminal of the diode D4 is electrically connected to the inverting input terminal of the operational amplifier U7 through the resistor R17; the input terminal of the diode D3 is electrically connected to the inverting input terminal of the operational amplifier U7 The inverting input terminal of the operational amplifier U7 is electrically connected; the non-inverting input terminal of the operational amplifier U7 is grounded through a resistor R20; the output terminal of the diode D4 is electrically connected to the non-inverting input terminal of the operational amplifier U8 through resistors R18 and R21 in sequence, and the resistors R18 and R21 are grounded through a capacitor C9; the inverting input terminal of the operational amplifier U8 is grounded through a resistor R23; the output terminal of the operational amplifier U8 is electrically connected to the inverting input terminal of the operational amplifier U8 through a resistor R22, is grounded through a capacitor C10, and is electrically connected to the MCU module.

[0016] In the above scheme, the sine wave output by the front stage passes through the follower composed of op amp U1, and is combined with another signal using an adder composed of op amp U2 to form the final output signal. The signal is output to the external conductivity head through terminal CN5. One of the signals passes through the conductivity head and is input to op amp U4 for detection and inversion amplification. After filtering, it is amplified again by op amp U5. After filtering, a DC voltage is obtained, which is finally input to the MCU module for processing. The other signal passes through the conductivity head and is similarly detected and amplified by op amp U7. After filtering, it is amplified again by op amp U8. After filtering again, a DC voltage is also obtained, which is finally input to the MCU module for processing.

[0017] Preferably, the communication module includes a communication interface chip, capacitors C11 to C15 and two communication channels; specifically:

[0018] The two ends of capacitor C11 are electrically connected to the C1+ pin and C1- pin of the communication interface chip respectively, the two ends of capacitor C12 are electrically connected to the C2+ pin and C2- pin of the communication interface chip respectively, the VS+ pin of the communication interface chip is grounded through capacitor C13, the VS- pin of the communication interface chip is grounded through capacitor C15, and the VCC pin of the communication interface chip is connected to a -5V voltage and is grounded through capacitor C14;

[0019] The T1OUT pin and R1IN pin of the communication interface chip are electrically connected to the two wiring terminals of one communication channel respectively, the T2OUT pin and R2IN pin of the communication interface chip are electrically connected to the two wiring terminals of another communication channel respectively, and the T1IN pin, R1OUT pin, T2IN pin and R2OUT pin of the communication interface chip are all electrically connected to the MCU module.

[0020] Preferably, the voltage stabilizing module includes a power stabilizing chip, capacitors C16 to C20, a diode D5 and a CN4 terminal; specifically: the power stabilizing chip receives a 5V input voltage and outputs a 3.3V voltage, the VIN pin of the power stabilizing chip is connected to the 5V voltage and is grounded through capacitors C16 and C17 respectively; the VOUT pin of the power stabilizing chip outputs a 3.3V voltage and is grounded through capacitors C18 and C19 respectively;

[0021] The four pins of the CN4 terminal are output signal, power supply +5V through diode D5, power supply -5V, and grounding through capacitor C20.

[0022] Preferably, the data isolation module includes two optical coupling isolation chips, capacitors C21 to C26 and resistors R24 to R29; specifically:

[0023] The MCU module and the input and output voltages through resistors R40 and R41 are connected to the input end of an optocoupler isolation chip; the VCC pin of the output end of the optocoupler isolation chip is grounded through capacitor C21 and electrically connected to the MCU module through resistor R24; the output end of the optocoupler isolation chip is connected to two pins of the MCU module and grounded through capacitors C22 and C23 respectively; the MCU module is connected to a 5V voltage through resistor R25;

[0024] The MCU module and the input and output voltages through resistors R26 and R27 are connected to the input end of another optocoupler isolation chip; the VCC pin of the output end of the optocoupler isolation chip is grounded through capacitor C24 and electrically connected to the MCU module through resistor R28. The output end of the optocoupler isolation chip is connected to two pins of the MCU module and are grounded through capacitors C25 and C26 respectively. The MCU module is connected to a 5V voltage through resistor R29.

[0025] Preferably, the data conversion module includes a CAN interface optical coupling isolation chip, a CAN output data conversion chip, a CAN interface, a discharge protector, resistors R30 to R35 and capacitors C27 to C30; specifically:

[0026] The MCU module and the input and output voltages through resistors R30 and R31 are connected to the input end of the CAN interface optocoupler isolation chip; the VCC pin of the output end of the CAN interface optocoupler isolation chip is grounded through capacitor C27, and the output end of the CAN interface optocoupler isolation chip is connected to two pins of the MCU module, and is grounded through capacitors C28 and C29 respectively, and is connected to a 3.3V voltage through resistors R32 and R33 respectively;

[0027] The VCC pin and the GND pin at the input end of the CAN output data conversion chip are electrically connected through a capacitor C30, the D pin and the R pin at the input end of the CAN output data conversion chip are electrically connected to two pins of the MCU module, and the RS pin at the output end of the CAN output data conversion chip is grounded through a resistor R34; the CANH pin and the CANL pin at the output end of the CAN output data conversion chip are respectively connected to the two ends of the resistor R35, and are both input to one end of the discharge protector, and the other end of the discharge protector is grounded, and at the same time, the two ports of the CAN interface are respectively connected to the CANH pin and the CANL pin at the output end of the CAN output data conversion chip.

[0028] Preferably, the temperature measurement module includes two temperature sensor connectors, capacitors C31 and C32, and a resistor R36; specifically:

[0029] The MCU module is connected to pin 2 of a temperature sensor connector, pin 3 of the temperature sensor connector is connected to a 3.3V voltage and grounded through capacitor C31, and pin 1 of the temperature sensor connector is grounded;

[0030] Pin 1 of another temperature sensor connector is connected to a 5V voltage, pin 2 is electrically connected to the MCU module via a resistor R36, pin 3 is electrically connected to the MCU module via a capacitor C32, and pin 3 is grounded.

[0031] Preferably, the MCU module includes an MCU chip, an external reference voltage chip, resistors R37 to R39 and a capacitor C33; specifically:

[0032] The MCU chip is electrically connected to pins 1 and 2 of the external reference voltage chip through resistor R38, and pins 1 and 2 of the external reference voltage chip are connected to a 3.3V voltage through resistor R37;

[0033] In the above solution, the external reference voltage chip provides a standard reference voltage for the MCU input;

[0034] The VDD pin of the MCU chip is connected in series and connected to the VDDA pin of the MCU chip through a resistor R39. The VDDA pin of the MCU chip is grounded through a capacitor C33. The VSS pin of the MCU chip is grounded.

[0035] The IN1+ pin of the MCU chip is electrically connected to the in-phase input terminal of the operational amplifier U1 through the resistor R1, and the IN2+ pin of the MCU chip is electrically connected to the in-phase input terminal of the operational amplifier U2 through the resistor R3; the other end of the resistor R14 is electrically connected to the OUT-MCU1-1 pin of the MCU chip; the output end of the operational amplifier U8 is electrically connected to the inverting input terminal of the operational amplifier U8 through the resistor R22, grounded through the capacitor C10, and electrically connected to the OUT-MCU2 pin of the MCU chip; the T1IN pin of the communication interface chip is electrically connected to the UART1TX pin of the MCU chip, the R1OUT pin of the communication interface chip is electrically connected to the UART1RX pin of the MCU chip, the T2IN pin of the communication interface chip is electrically connected to the UART2TX pin of the MCU chip, and the R2OUT pins of the communication interface chip are all electrically connected to the UART2RX pin of the MCU chip;

[0036] The UART1TX pin of the MCU chip, the UART1RX pin of the MCU chip, and the input and output voltages through resistors R22 and R23 are connected to the input end of an optocoupler isolation chip; the VCC pin of the output end of the optocoupler isolation chip is grounded through a capacitor C21, and is electrically connected to the UART1TX pin of the MCU chip through a resistor R24, the output end of the optocoupler isolation chip is connected to the UART1TX pin and the UART1RX pin of the MCU chip, and are grounded through capacitors C22 and C23 respectively, and the UART1RX pin is connected to a 5V voltage through a resistor R25;

[0037] The UART2TX pin of the MCU chip, the UART2RX pin of the MCU chip and the input and output voltages through resistors R26 and R27 are connected to the input end of another optocoupler isolation chip; the VCC pin of the output end of the optocoupler isolation chip is grounded through a capacitor C24, and is electrically connected to the UART2TX pin of the MCU chip through a resistor R28, the output end of the optocoupler isolation chip is connected to the UART2TX pin of the MCU chip, the UART2RX pin of the MCU chip, and are grounded through capacitors C25 and C26 respectively, and the UART2RX pin of the MCU chip is connected to a 5V voltage through a resistor R29;

[0038] The CAN1TX pin of the MCU chip, the CAN1RX pin of the MCU chip, and the input and output voltages of the resistors R30 and R31 are connected to the input end of the CAN interface optocoupler isolation chip, the output end of the CAN interface optocoupler isolation chip is connected to the CAN1TX pin and CAN1RX pin of the MCU chip, and the D pin and R pin of the input end of the CAN output data conversion chip are electrically connected to the CAN1TX pin and CAN1RX pin of the MCU chip;

[0039] The T1M1CH1 pin of the MCU chip is connected to the 2nd pin of a temperature sensor connector; the 1st pin of another temperature sensor connector is connected to a 5V voltage, the 2nd pin is electrically connected to the TEMP pin of the MCU chip through a resistor R36, and the 3rd pin is electrically connected to the TEMP pin of the MCU chip through a capacitor C32.

[0040] Preferably, a clock module is further included, the clock module is specifically a clock circuit, and two ends of the clock circuit are electrically connected to the OSCIN pin and the OSCOUT pin of the MCU chip respectively. The clock module provides a system clock for the MCU module.

[0041] Preferably, it also includes a filtering module, which is specifically a filtering circuit.

[0042] The beneficial effects of the present invention are specifically as follows:

[0043] The present invention provides a dialysate conductivity monitoring system, the circuit automatically adapts to the inner diameter of the carbon ring and the isolation column, and the measurement error is very small. It has its own carbon ring and isolation column calcium detection function, which makes maintenance more convenient and simple; the output signal adopts MCU closed-loop control, the signal amplitude is adjustable, and the conductivity head is automatically matched and automatically corrected; CAN communication is adopted, which makes debugging more convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A schematic diagram of a system module provided by an embodiment of the present invention;

[0045] Figure 2 A schematic diagram of a signal input module provided by an embodiment of the present invention;

[0046] Figure 3 A schematic diagram of a communication module provided by an embodiment of the present invention;

[0047] Figure 4 A schematic diagram of a voltage stabilizing module provided in one embodiment of the present invention;

[0048] Figure 5 A schematic diagram of a data isolation module provided by an embodiment of the present invention;

[0049] Figure 6 A schematic diagram of a data conversion module provided by an embodiment of the present invention;

[0050] Figure 7 A schematic diagram of a temperature measurement module provided by an embodiment of the present invention;

[0051] Figure 8 A schematic diagram of an MCU module provided by an embodiment of the present invention;

[0052] Fig. 9 A schematic diagram of a clock module provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] See also Figure 1 , this embodiment provides a dialysate conductivity monitoring system, including a signal input module, an MCU module, a communication module, a voltage stabilization module, a data isolation module, a data conversion module, and a temperature measurement module;

[0055] The output end of the signal input module, the output end of the voltage stabilization module and the output end of the temperature measurement module are electrically connected to the input end of the MCU module, and the data isolation module, the data conversion module and the communication module are all electrically connected to the MCU module in a bidirectional manner;

[0056] The signal input module is used to generate the reference signal for conductivity detection and the input signal of the detection head; the voltage stabilization module is used to provide a stable voltage; the temperature measurement module is used to measure the temperature value of the standard liquid; the MCU module is used for data processing; the communication module is used to realize data interaction; the data isolation module is used to realize communication data isolation, and the data conversion module is used to convert output data.

[0057] In the above scheme, the circuit automatically adapts to the inner diameter of the carbon ring and the isolation column, and the measurement error is very small. It has its own calcium detection function for the carbon ring and the isolation column, which makes maintenance more convenient and simple. The output signal adopts MCU closed-loop control, the signal amplitude is adjustable, and the conductivity head is automatically matched and automatically corrected. CAN communication is adopted, which makes debugging more convenient.

[0058] Preferably, the signal input module includes several operational amplifiers. The sine wave output by the MCU module passes through a follower composed of operational amplifiers, and is combined with another signal using an adder to finally output a signal to an external conductivity head; both signals are input into the operational amplifier after passing through the conductivity head for detection and inversion amplification, and are amplified again by the operational amplifier after filtering to obtain a DC voltage input into the MCU module for processing; wherein, the number of amplification levels of the operational amplifier for the first time is greater than the number of amplification levels for the second time.

[0059] Preferably, see Figure 2 The signal input module includes capacitors C1 to C10, resistors R1 to R23, diodes D1 to D4, operational amplifiers U1 to U8 and 5 plug-in connectors; specifically:

[0060] The MCU module is electrically connected to the in-phase input terminal of the operational amplifier U1 through the resistor R1, and the output terminal of the operational amplifier U1 is electrically connected to the inverting input terminal of the operational amplifier U1 and one end of the resistor R2; the positive and negative electrodes of the operational amplifier U1 are both connected to a 5V voltage and are grounded through capacitors C1 and C2 respectively; the other end of the resistor R2 is electrically connected to the inverting input terminal of the operational amplifier U2, the MCU module is electrically connected to the in-phase input terminal of the operational amplifier U2 through the resistor R3, and the in-phase input terminal of the operational amplifier U2 is grounded through the resistor R4, the output terminal of the operational amplifier U2 is electrically connected to the inverting input terminal of the operational amplifier U2 through the resistor R5, and is connected to the 4 pins of the 5 plug-in connector;

[0061] Pin 2 of the 5-pin connector is electrically connected to the non-inverting input terminal of the operational amplifier U3 through the resistor R6, and is electrically connected to the inverting input terminal of the operational amplifier U4; the output terminal of the operational amplifier U3 is electrically connected to the inverting input terminal of the operational amplifier U4 through the capacitor C3 and the resistor R7 in sequence, and is electrically connected to the inverting input terminal of the operational amplifier U3, the positive and negative electrodes of the operational amplifier U3 are both connected to a 5V voltage, and are grounded through the capacitor C4 and the capacitor C5 respectively; the non-inverting input terminal of the operational amplifier U4 is grounded through the resistor R16, the output terminal of the operational amplifier U4 is electrically connected to the input terminal of the diode D1 and the output terminal of the diode D2 respectively, the output terminal of the diode D1 is electrically connected to the inverting input terminal of the operational amplifier U4, and the two The input end of the diode D2 is electrically connected to one end of the resistor R8 and one end of the resistor R9, and the other end of the resistor R8 is electrically connected to the inverting input end of the operational amplifier U4; the other end of the resistor R9 is grounded through the capacitor C6 and is electrically connected to one end of the resistor R10; the other end of the resistor R10 is electrically connected to the inverting input end of the operational amplifier U5, and the non-inverting input end of the operational amplifier U5 is grounded through the resistor R12; the output end of the operational amplifier U5 is electrically connected to the inverting input end of the operational amplifier U5 through the resistor R11, and is electrically connected to one end of the resistor R13; the other end of the resistor R13 is grounded through the capacitor C7, and is electrically connected to one end of the resistor R14, and the other end of the resistor R14 is electrically connected to the MCU module;

[0062] Pin 3 of the 5-pin connector is electrically connected to the non-inverting input terminal of the operational amplifier U6 through the resistor R15; the output terminal of the operational amplifier U6 is electrically connected to the inverting input terminal of the operational amplifier U6, and is electrically connected to the inverting input terminal of the operational amplifier U7 through the capacitor C8 and the resistor R19 in sequence; the non-inverting input terminal of the operational amplifier U7 is electrically connected to the output terminal of the diode D3 and the input terminal of the diode D4 respectively; the output terminal of the diode D4 is electrically connected to the inverting input terminal of the operational amplifier U7 through the resistor R17; the input terminal of the diode D3 is electrically connected to the inverting input terminal of the operational amplifier U7 The inverting input terminal of the operational amplifier U7 is electrically connected; the non-inverting input terminal of the operational amplifier U7 is grounded through a resistor R20; the output terminal of the diode D4 is electrically connected to the non-inverting input terminal of the operational amplifier U8 through resistors R18 and R21 in sequence, and the resistors R18 and R21 are grounded through a capacitor C9; the inverting input terminal of the operational amplifier U8 is grounded through a resistor R23; the output terminal of the operational amplifier U8 is electrically connected to the inverting input terminal of the operational amplifier U8 through a resistor R22, is grounded through a capacitor C10, and is electrically connected to the MCU module.

[0063] Preferably, see Figure 3 The communication module includes a communication interface chip, capacitors C11 to C15 and two communication channels; specifically:

[0064] The two ends of capacitor C11 are electrically connected to the C1+ pin and C1- pin of the communication interface chip respectively, the two ends of capacitor C12 are electrically connected to the C2+ pin and C2- pin of the communication interface chip respectively, the VS+ pin of the communication interface chip is grounded through capacitor C13, the VS- pin of the communication interface chip is grounded through capacitor C15, and the VCC pin of the communication interface chip is connected to a -5V voltage and is grounded through capacitor C14;

[0065] The T1OUT pin and R1IN pin of the communication interface chip are electrically connected to the two wiring terminals of one communication channel respectively, the T2OUT pin and R2IN pin of the communication interface chip are electrically connected to the two wiring terminals of another communication channel respectively, and the T1IN pin, R1OUT pin, T2IN pin and R2OUT pin of the communication interface chip are all electrically connected to the MCU module.

[0066] Preferably, see Figure 4 , the voltage stabilizing module includes a power voltage stabilizing chip, capacitors C16 to C20, a diode D5 and a CN4 terminal; specifically: the power voltage stabilizing chip receives a 5V input voltage and outputs a 3.3V voltage, the VIN pin of the power voltage stabilizing chip is connected to the 5V voltage, and is grounded through capacitors C16 and C17 respectively; the VOUT pin of the power voltage stabilizing chip outputs a 3.3V voltage, and is grounded through capacitors C18 and C19 respectively;

[0067] The four pins of the CN4 terminal are output signal, power supply +5V through diode D5, power supply -5V, and grounding through capacitor C20.

[0068] Preferably, see Figure 5 The data isolation module includes two optocoupler isolation chips, capacitors C21 to C26 and resistors R24 to R29; specifically:

[0069] The MCU module and the input and output voltages through resistors R40 and R41 are connected to the input end of an optocoupler isolation chip; the VCC pin of the output end of the optocoupler isolation chip is grounded through capacitor C21 and electrically connected to the MCU module through resistor R24; the output end of the optocoupler isolation chip is connected to two pins of the MCU module and grounded through capacitors C22 and C23 respectively; the MCU module is connected to a 5V voltage through resistor R25;

[0070] The MCU module and the input and output voltages through resistors R26 and R27 are connected to the input end of another optocoupler isolation chip; the VCC pin of the output end of the optocoupler isolation chip is grounded through capacitor C24 and electrically connected to the MCU module through resistor R28. The output end of the optocoupler isolation chip is connected to two pins of the MCU module and are grounded through capacitors C25 and C26 respectively. The MCU module is connected to a 5V voltage through resistor R29.

[0071] Preferably, see Figure 6 The data conversion module includes a CAN interface optical coupling isolation chip, a CAN output data conversion chip, a CAN interface, a discharge protector, resistors R30 to R35 and capacitors C27 to C30; specifically:

[0072] The MCU module and the input and output voltages through resistors R30 and R31 are connected to the input end of the CAN interface optocoupler isolation chip; the VCC pin of the output end of the CAN interface optocoupler isolation chip is grounded through capacitor C27, and the output end of the CAN interface optocoupler isolation chip is connected to two pins of the MCU module, and is grounded through capacitors C28 and C29 respectively, and is connected to a 3.3V voltage through resistors R32 and R33 respectively;

[0073] The VCC pin and the GND pin at the input end of the CAN output data conversion chip are electrically connected through a capacitor C30, the D pin and the R pin at the input end of the CAN output data conversion chip are electrically connected to two pins of the MCU module, and the RS pin at the output end of the CAN output data conversion chip is grounded through a resistor R34; the CANH pin and the CANL pin at the output end of the CAN output data conversion chip are respectively connected to the two ends of the resistor R35, and are both input to one end of the discharge protector, and the other end of the discharge protector is grounded, and at the same time, the two ports of the CAN interface are respectively connected to the CANH pin and the CANL pin at the output end of the CAN output data conversion chip.

[0074] Preferably, see Figure 7 The temperature measurement module includes two temperature sensor connectors, capacitors C31 to C32, and resistor R36; specifically:

[0075] The MCU module is connected to pin 2 of a temperature sensor connector, pin 3 of the temperature sensor connector is connected to a 3.3V voltage and grounded through capacitor C31, and pin 1 of the temperature sensor connector is grounded;

[0076] Pin 1 of another temperature sensor connector is connected to a 5V voltage, pin 2 is electrically connected to the MCU module via a resistor R36, pin 3 is electrically connected to the MCU module via a capacitor C32, and pin 3 is grounded.

[0077] Preferably, see Figure 8 , the MCU module includes an MCU chip, an external reference voltage chip, resistors R37 to R39 and a capacitor C33; specifically:

[0078] The MCU chip is electrically connected to pins 1 and 2 of the external reference voltage chip through resistor R38, and pins 1 and 2 of the external reference voltage chip are connected to a 3.3V voltage through resistor R37;

[0079] The VDD pin of the MCU chip is connected in series and connected to the VDDA pin of the MCU chip through a resistor R39. The VDDA pin of the MCU chip is grounded through a capacitor C33. The VSS pin of the MCU chip is grounded.

[0080] The IN1+ pin of the MCU chip is electrically connected to the in-phase input terminal of the operational amplifier U1 through the resistor R1, and the IN2+ pin of the MCU chip is electrically connected to the in-phase input terminal of the operational amplifier U2 through the resistor R3; the other end of the resistor R14 is electrically connected to the OUT-MCU1-1 pin of the MCU chip; the output end of the operational amplifier U8 is electrically connected to the inverting input terminal of the operational amplifier U8 through the resistor R22, grounded through the capacitor C10, and electrically connected to the OUT-MCU2 pin of the MCU chip; the T1IN pin of the communication interface chip is electrically connected to the UART1TX pin of the MCU chip, the R1OUT pin of the communication interface chip is electrically connected to the UART1RX pin of the MCU chip, the T2IN pin of the communication interface chip is electrically connected to the UART2TX pin of the MCU chip, and the R2OUT pins of the communication interface chip are all electrically connected to the UART2RX pin of the MCU chip;

[0081] The UART1TX pin of the MCU chip, the UART1RX pin of the MCU chip, and the input and output voltages through resistors R22 and R23 are connected to the input end of an optocoupler isolation chip; the VCC pin of the output end of the optocoupler isolation chip is grounded through a capacitor C21, and is electrically connected to the UART1TX pin of the MCU chip through a resistor R24, the output end of the optocoupler isolation chip is connected to the UART1TX pin and the UART1RX pin of the MCU chip, and are grounded through capacitors C22 and C23 respectively, and the UART1RX pin is connected to a 5V voltage through a resistor R25;

[0082] The UART2TX pin of the MCU chip, the UART2RX pin of the MCU chip and the input and output voltages through resistors R26 and R27 are connected to the input end of another optocoupler isolation chip; the VCC pin of the output end of the optocoupler isolation chip is grounded through a capacitor C24, and is electrically connected to the UART2TX pin of the MCU chip through a resistor R28, the output end of the optocoupler isolation chip is connected to the UART2TX pin of the MCU chip, the UART2RX pin of the MCU chip, and are grounded through capacitors C25 and C26 respectively, and the UART2RX pin of the MCU chip is connected to a 5V voltage through a resistor R29;

[0083] The CAN1TX pin of the MCU chip, the CAN1RX pin of the MCU chip, and the input and output voltages of the resistors R30 and R31 are connected to the input end of the CAN interface optocoupler isolation chip, the output end of the CAN interface optocoupler isolation chip is connected to the CAN1TX pin and CAN1RX pin of the MCU chip, and the D pin and R pin of the input end of the CAN output data conversion chip are electrically connected to the CAN1TX pin and CAN1RX pin of the MCU chip;

[0084] The T1M1CH1 pin of the MCU chip is connected to the 2nd pin of a temperature sensor connector; the 1st pin of another temperature sensor connector is connected to a 5V voltage, the 2nd pin is electrically connected to the TEMP pin of the MCU chip through a resistor R36, and the 3rd pin is electrically connected to the TEMP pin of the MCU chip through a capacitor C32.

[0085] Preferably, see Fig. 9 , and also includes a clock module, which is specifically a clock circuit, and two ends of the clock circuit are electrically connected to the OSCIN pin and the OSCOUT pin of the MCU chip respectively.

[0086] Preferably, it also includes a filtering module, which is specifically a filtering circuit.

[0087] A digital measuring device using an MCU uses a carbon ring and an isolation column assembly as an input detection head. By inputting a sine wave signal with adjustable amplitude and frequency at one end of the carbon ring and the isolation column, the signal flows through an assembly composed of multiple groups of carbon rings and isolation columns, and a wire is led out at each carbon ring intersection as the signal output. The conductivity value is calculated using the resistance value of the liquid flowing inside the carbon ring and the isolation column. Because the input signal amplitude and frequency are adjustable, the circuit automatically adapts to the size of the inner diameter of the carbon ring and the isolation column, and will not cause a large measurement error due to the processing error of the inner diameter of the carbon ring and the isolation column. It has a built-in calcium detection function for the carbon ring and the isolation column, which makes maintenance more convenient and simple.

[0088] Specifically, the above scheme can be that the MCU module generates a sine wave with adjustable output frequency and amplitude through the digital-to-analog conversion of the IN1 pin as the reference signal for conductivity detection, and the IN2 pin outputs a DC voltage superimposed on the reference voltage as the input signal of the detection head. After the signal passes through the carbon ring and the liquid flowing in the isolation column, the signal will be reduced due to the internal resistance of the liquid. The final signal will be input to the 3rd and 13th pins of the operational amplifier. After amplification, limiting and filtering by the operational amplifier, the DC voltage is output as the final output signal after passing through the RC filter circuit. After the MCU converts the DC voltage through the ADC, it is converted into a digital quantity and sent out through the CAN bus. The DC superimposed signal output by IN2 corrects the unequal positive and negative amplitudes of the sine wave, thereby achieving more accurate conductivity detection errors.

[0089] The other signal is used as a calcium deposition detection signal. After amplification, limiting and filtering, it is sent to the ADC2 pin of the MCU to realize the function of self-checking whether calcium deposition occurs when the device is powered on, which greatly facilitates the maintenance of the conductivity component. The principle of calcium deposition detection is that after the conductivity component is calibrated, the MCU output waveform is fixed. The value of ADC1 can be obtained by reading the MCU, and then the voltage value after the standard solution passes through is read by ADC2 and recorded in the FLASH. By comparing the voltage value, it can be found whether there is a deviation inside the conductivity. At the same time, the values ​​of the two groups of ADC1 and ADC2 are compared, and then the change of the inner diameter is calculated. Specifically, the change of the inner diameter is calculated by the difference between the two ADC1 and ADC2. If there is an error, it is considered that calcium deposition has occurred inside.

[0090] The system has a self-calibration function. As long as the conductivity value and temperature value of the standard liquid that has passed through the carbon ring and the isolation column are input to the upper computer interface, the MCU output reference waveform can be automatically adjusted to dynamically adjust the current conductivity value to the conductivity value of the standard liquid. In the implementation process, by injecting the standard conductivity liquid, the signal will have different differential voltage amplitudes after passing through the standard conductivity liquid. The MCU reads the voltage value fed back through the ADC and reads the temperature during calibration at the same time. After conversion by the conversion formula, the current conductivity value is calculated. By comparing the current conductivity value with the standard conductivity value, the input signal amplitude is dynamically adjusted, the waveform amplitude is reduced or increased, and the output meets the required value and accuracy of ±0.1.

[0091] Through experiments, different liquids or different concentrations of the same liquid have different corresponding resistivities, and the amount of signal reduction after the signal passes through is different. Through experiments, the corresponding relationship between them can be obtained. Then the conductivity value can be calculated through the conversion formula. At the same time, the conversion formula corresponding to conductivity at different temperatures is as follows:

[0092] Conductivity value at 25 degrees = actual conductivity value / (1+0.021*(t-25)) (where: 0.021 is the temperature compensation coefficient, t is the actual water temperature).

[0093] In the present invention, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0094] In the description of this specification, if the terms "one embodiment", "some embodiments", "specific embodiments" and the like appear, it means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0095] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A dialysate conductivity monitoring system, characterized in that: include: Signal input module, MCU module, communication module, Voltage stabilization module, data isolation module, data conversion module, temperature measurement module; The output end of the signal input module, the output end of the voltage stabilization module and the output end of the temperature measurement module are electrically connected to the input end of the MCU module; the data isolation module, the data conversion module and the communication module are all bidirectionally electrically connected to the MCU module; The signal input module is used to generate the reference signal of conductivity detection and the input signal of the detection head; the voltage stabilization module is used to provide a stable voltage; the temperature measurement module is used to measure the temperature value of the standard liquid; the MCU module is used to process data; the communication module is used to realize data interaction; the data isolation module is used to realize communication data isolation; the data conversion module is used to convert output data; The conductivity monitoring system uses a carbon ring and spacer column assembly as an input detection head; The MCU module generates a sine wave with adjustable input frequency and amplitude as the reference signal for conductivity detection through digital-to-analog conversion, and outputs a DC voltage superimposed on the reference voltage as the input signal of the detection head, and corrects the amplitude of the sine wave through the DC superimposed signal; By inputting a sine wave signal with adjustable amplitude and frequency at one end of the carbon ring and isolation column assembly, the conductivity head is automatically matched and automatically corrected. The signal flows through multiple groups of carbon ring and isolation column assemblies, and a wire is connected at the intersection of each carbon ring and isolation column assembly as the signal output; the conductivity value is calculated using the resistance value of the liquid flowing inside the carbon ring and isolation column assembly.

2. A dialysate conductivity monitoring system according to claim 1, characterized in that: The signal input module includes several operational amplifiers. The sine wave output by the MCU module passes through a follower composed of operational amplifiers, and is combined with another signal using an adder to finally output a signal to an external conductivity head. Both signals pass through the conductivity head and are input into the operational amplifier for detection and inversion amplification. After filtering, they are amplified again by the operational amplifier to obtain a DC voltage input to the MCU module for processing. Among them, the number of amplification levels of the operational amplifier for the first time is greater than the number of amplification levels for the second time.

3. A dialysate conductivity monitoring system according to claim 2, characterized in that: The signal input module includes capacitors C1 to C10, resistors R1 to R23, diodes D1 to D4, operational amplifiers U1 to U8 and 5 plug-in connectors; specifically: The MCU module is electrically connected to the in-phase input terminal of the operational amplifier U1 through the resistor R1, and the output terminal of the operational amplifier U1 is electrically connected to the inverting input terminal of the operational amplifier U1 and one end of the resistor R2; the positive and negative electrodes of the operational amplifier U1 are both connected to a 5V voltage and are grounded through capacitors C1 and C2 respectively; the other end of the resistor R2 is electrically connected to the inverting input terminal of the operational amplifier U2, the MCU module is electrically connected to the in-phase input terminal of the operational amplifier U2 through the resistor R3, and the in-phase input terminal of the operational amplifier U2 is grounded through the resistor R4, the output terminal of the operational amplifier U2 is electrically connected to the inverting input terminal of the operational amplifier U2 through the resistor R5, and is connected to the 4 pins of the 5 plug-in connector; Pin 2 of the 5-pin connector is electrically connected to the non-inverting input terminal of the operational amplifier U3 through the resistor R6, and is electrically connected to the inverting input terminal of the operational amplifier U4; the output terminal of the operational amplifier U3 is electrically connected to the inverting input terminal of the operational amplifier U4 through the capacitor C3 and the resistor R7 in sequence, and is electrically connected to the inverting input terminal of the operational amplifier U3, the positive and negative electrodes of the operational amplifier U3 are both connected to a 5V voltage, and are grounded through the capacitor C4 and the capacitor C5 respectively; the non-inverting input terminal of the operational amplifier U4 is grounded through the resistor R16, the output terminal of the operational amplifier U4 is electrically connected to the input terminal of the diode D1 and the output terminal of the diode D2 respectively, the output terminal of the diode D1 is electrically connected to the inverting input terminal of the operational amplifier U4, and the two The input end of the diode D2 is electrically connected to one end of the resistor R8 and one end of the resistor R9, and the other end of the resistor R8 is electrically connected to the inverting input end of the operational amplifier U4; the other end of the resistor R9 is grounded through the capacitor C6 and is electrically connected to one end of the resistor R10; the other end of the resistor R10 is electrically connected to the inverting input end of the operational amplifier U5, and the non-inverting input end of the operational amplifier U5 is grounded through the resistor R12; the output end of the operational amplifier U5 is electrically connected to the inverting input end of the operational amplifier U5 through the resistor R11, and is electrically connected to one end of the resistor R13; the other end of the resistor R13 is grounded through the capacitor C7, and is electrically connected to one end of the resistor R14, and the other end of the resistor R14 is electrically connected to the MCU module; Pin 3 of the 5-pin connector is electrically connected to the non-inverting input terminal of the operational amplifier U6 through the resistor R15; the output terminal of the operational amplifier U6 is electrically connected to the inverting input terminal of the operational amplifier U6, and is electrically connected to the inverting input terminal of the operational amplifier U7 through the capacitor C8 and the resistor R19 in sequence; the non-inverting input terminal of the operational amplifier U7 is electrically connected to the output terminal of the diode D3 and the input terminal of the diode D4 respectively; the output terminal of the diode D4 is electrically connected to the inverting input terminal of the operational amplifier U7 through the resistor R17; the input terminal of the diode D3 is electrically connected to the inverting input terminal of the operational amplifier U7 The inverting input terminal of the operational amplifier U7 is electrically connected; the non-inverting input terminal of the operational amplifier U7 is grounded through a resistor R20; the output terminal of the diode D4 is electrically connected to the non-inverting input terminal of the operational amplifier U8 through resistors R18 and R21 in sequence, and the resistors R18 and R21 are grounded through a capacitor C9; the inverting input terminal of the operational amplifier U8 is grounded through a resistor R23; the output terminal of the operational amplifier U8 is electrically connected to the inverting input terminal of the operational amplifier U8 through a resistor R22, is grounded through a capacitor C10, and is electrically connected to the MCU module.

4. A dialysate conductivity monitoring system according to claim 1, characterized in that: The communication module includes a communication interface chip, capacitors C11 to C15 and two communication channels; specifically: The two ends of capacitor C11 are electrically connected to the C1+ pin and C1- pin of the communication interface chip respectively, the two ends of capacitor C12 are electrically connected to the C2+ pin and C2- pin of the communication interface chip respectively, the VS+ pin of the communication interface chip is grounded through capacitor C13, the VS- pin of the communication interface chip is grounded through capacitor C15, and the VCC pin of the communication interface chip is connected to a -5V voltage and is grounded through capacitor C14; The T1OUT pin and R1IN pin of the communication interface chip are electrically connected to the two wiring terminals of one communication channel respectively, the T2OUT pin and R2IN pin of the communication interface chip are electrically connected to the two wiring terminals of another communication channel respectively, and the T1IN pin, R1OUT pin, T2IN pin and R2OUT pin of the communication interface chip are all electrically connected to the MCU module.

5. A dialysate conductivity monitoring system according to claim 1, characterized in that: The voltage stabilizing module includes a power stabilizing chip, capacitors C16 to C20, a diode D5 and a CN4 terminal; specifically: the VIN pin of the power stabilizing chip is connected to a 5V voltage and is grounded through capacitors C16 and C17 respectively; the VOUT pin of the power stabilizing chip outputs a 3.3V voltage and is grounded through capacitors C18 and C19 respectively; The four pins of the CN4 terminal are output signal, power supply +5V through diode D5, power supply -5V, and grounding through capacitor C20.

6. A dialysate conductivity monitoring system according to claim 1, characterized in that: The data isolation module includes two optical coupling isolation chips, capacitors C21 to C26, resistors R24 to R29, resistor R40 and resistor R41; specifically: The MCU module and the input and output voltages through resistors R40 and R41 are connected to the input end of an optocoupler isolation chip; the VCC pin of the output end of the optocoupler isolation chip is grounded through capacitor C21 and electrically connected to the MCU module through resistor R24; the output end of the optocoupler isolation chip is connected to two pins of the MCU module and grounded through capacitors C22 and C23 respectively; the MCU module is connected to a 5V voltage through resistor R25; The MCU module, the input and output voltages through resistors R26 and R27 are connected to the input end of another optocoupler isolation chip; The VCC pin of the output end of the optocoupler isolation chip is grounded through capacitor C24 and electrically connected to the MCU module through resistor R28. The output end of the optocoupler isolation chip is connected to two pins of the MCU module and grounded through capacitors C25 and C26 respectively. The MCU module is connected to a 5V voltage through resistor R29.

7. A dialysate conductivity monitoring system according to claim 1, characterized in that: The data conversion module includes a CAN interface optical coupling isolation chip, a CAN output data conversion chip, a CAN interface, a discharge protector, resistors R30 to R35 and capacitors C27 to C30; Specifically: The MCU module and the input and output voltages through resistors R30 and R31 are connected to the input end of the CAN interface optocoupler isolation chip; the VCC pin of the output end of the CAN interface optocoupler isolation chip is grounded through capacitor C27, and the output end of the CAN interface optocoupler isolation chip is connected to two pins of the MCU module, and is grounded through capacitors C28 and C29 respectively, and is connected to a 3.3V voltage through resistors R32 and R33 respectively; The VCC pin and the GND pin at the input end of the CAN output data conversion chip are electrically connected through a capacitor C30, the D pin and the R pin at the input end of the CAN output data conversion chip are electrically connected to two pins of the MCU module, and the RS pin at the output end of the CAN output data conversion chip is grounded through a resistor R34; the CANH pin and the CANL pin at the output end of the CAN output data conversion chip are respectively connected to the two ends of the resistor R35, and are both input to one end of the discharge protector, and the other end of the discharge protector is grounded, and at the same time, the two ports of the CAN interface are respectively connected to the CANH pin and the CANL pin at the output end of the CAN output data conversion chip.

8. A dialysate conductivity monitoring system according to claim 1, characterized in that: The temperature measurement module includes two temperature sensor connectors, capacitors C31 and C32, and a resistor R36; specifically: The MCU module is connected to pin 2 of a temperature sensor connector, pin 3 of the temperature sensor connector is connected to a 3.3V voltage and grounded through capacitor C31, and pin 1 of the temperature sensor connector is grounded; Pin 1 of another temperature sensor connector is connected to a 5V voltage, pin 2 is electrically connected to the MCU module via a resistor R36, pin 3 is electrically connected to the MCU module via a capacitor C32, and pin 3 is grounded.

9. A dialysate conductivity monitoring system according to claim 1, characterized in that: The MCU module includes an MCU chip, an external reference voltage chip, resistors R37 to R39 and a capacitor C33; specifically: The MCU chip is electrically connected to pins 1 and 2 of the external reference voltage chip through resistor R38, and pins 1 and 2 of the external reference voltage chip are connected to a 3.3V voltage through resistor R37; The VDD pin of the MCU chip is connected in series and connected to the VDDA pin of the MCU chip through a resistor R39. The VDDA pin of the MCU chip is grounded through a capacitor C33. The VSS pin of the MCU chip is grounded. The IN1+ pin of the MCU chip is electrically connected to the in-phase input terminal of the operational amplifier U1 through the resistor R1, and the IN2+ pin of the MCU chip is electrically connected to the in-phase input terminal of the operational amplifier U2 through the resistor R3; the other end of the resistor R14 is electrically connected to the OUT-MCU1-1 pin of the MCU chip; the output end of the operational amplifier U8 is electrically connected to the inverting input terminal of the operational amplifier U8 through the resistor R22, grounded through the capacitor C10, and electrically connected to the OUT-MCU2 pin of the MCU chip; the T1IN pin of the communication interface chip is electrically connected to the UART1TX pin of the MCU chip, the R1OUT pin of the communication interface chip is electrically connected to the UART1RX pin of the MCU chip, the T2IN pin of the communication interface chip is electrically connected to the UART2TX pin of the MCU chip, and the R2OUT pins of the communication interface chip are all electrically connected to the UART2RX pin of the MCU chip; The UART1TX pin of the MCU chip, the UART1RX pin of the MCU chip, and the input and output voltages through resistors R22 and R23 are connected to the input end of an optocoupler isolation chip; the VCC pin of the output end of the optocoupler isolation chip is grounded through a capacitor C21, and is electrically connected to the UART1TX pin of the MCU chip through a resistor R24, the output end of the optocoupler isolation chip is connected to the UART1TX pin and the UART1RX pin of the MCU chip, and are grounded through capacitors C22 and C23 respectively, and the UART1RX pin is connected to a 5V voltage through a resistor R25; The UART2TX pin of the MCU chip, the UART2RX pin of the MCU chip and the input and output voltages through resistors R26 and R27 are connected to the input end of another optocoupler isolation chip; the VCC pin of the output end of the optocoupler isolation chip is grounded through a capacitor C24, and is electrically connected to the UART2TX pin of the MCU chip through a resistor R28, the output end of the optocoupler isolation chip is connected to the UART2TX pin of the MCU chip, the UART2RX pin of the MCU chip, and are grounded through capacitors C25 and C26 respectively, and the UART2RX pin of the MCU chip is connected to a 5V voltage through a resistor R29; The CAN1TX pin of the MCU chip, the CAN1RX pin of the MCU chip, and the input and output voltages of the resistors R30 and R31 are connected to the input end of the CAN interface optocoupler isolation chip, the output end of the CAN interface optocoupler isolation chip is connected to the CAN1TX pin and CAN1RX pin of the MCU chip, and the D pin and R pin of the input end of the CAN output data conversion chip are electrically connected to the CAN1TX pin and CAN1RX pin of the MCU chip; The T1M1CH1 pin of the MCU chip is connected to the 2nd pin of a temperature sensor connector; the 1st pin of another temperature sensor connector is connected to a 5V voltage, the 2nd pin is electrically connected to the TEMP pin of the MCU chip through a resistor R36, and the 3rd pin is electrically connected to the TEMP pin of the MCU chip through a capacitor C32.

10. A dialysate conductivity monitoring system according to claim 9, characterized in that: It also includes a clock module, which is specifically a clock circuit, and the two ends of the clock circuit are electrically connected to the OSCIN pin and the OSCOUT pin of the MCU chip respectively; it also includes a filter module, which is specifically a filter circuit.

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