A multi-channel high-precision AD acquisition correction circuit and its fast correction method

Abstract

The invention discloses a multi-channel high-precision AD acquisition correction circuit, comprising an AD conversion part and a verification table part; the verification table part comprises a digital control power supply, the digital control power supply provides a plurality of power input signal channels for the AD conversion part and provides a voltage input signal channel for the verification table; the AD conversion part comprises a plurality of first AD acquisition chips, a first single-chip computer, a first RS232 chip, a plurality of horizontal slide switches, a plurality of first instrument amplifiers, and a plurality of first resistors; each of the first AD acquisition chips is respectively connected to a power input signal channel through a horizontal slide switch, a first instrument amplifier and a first resistor; the invention verifies the AD conversion part to obtain a correction coefficient K value of each voltage segment, thereby ensuring the high precision of the AD conversion part, and at the same time, adopting this circuit structure for correction reduces the time consumption of manual correction, and has higher accuracy, is suitable for batch correction, and is more convenient.

Description

Technical Field

[0001] The invention belongs to the technical field of AD acquisition correction, and in particular relates to a multi-channel high-precision AD acquisition correction circuit and a rapid correction method thereof. Background Art

[0002] In the field of environmental monitoring, in order to collect pollutant factors such as the pH value of sewage and COD concentration in real time, pH meters and COD analyzers are often used. These primary instruments often output 4-20mA analog quantities. According to the National Environmental Protection Standard of the People's Republic of China HJ 477-2009 "Technical Requirements for Online Automatic Monitoring (Monitoring) Data Acquisition and Transmission Instruments for Pollution Sources": Data acquisition error ≤ 1‰, it is particularly important to design a high-precision AD conversion part. However, due to the nonlinear error of the AD chip, the AD acquisition accuracy is seriously affected. Although some manufacturers have made relevant corrections, it is time-consuming, the accuracy is not high, and it is not convenient for mass production. Summary of the invention

[0003] The object of the present invention is to provide a multi-channel high-precision AD acquisition correction circuit and a fast correction method thereof, so as to solve the defects or problems mentioned in the background technology.

[0004] To achieve the above-mentioned purpose of the invention, an embodiment of the present invention provides a multi-channel high-precision AD acquisition correction circuit, characterized in that it includes an AD conversion part and a verification table part; the verification table part includes a digital control power supply, and the digital control power supply provides multiple power input signal channels for the AD conversion part and provides a voltage input signal channel for the verification table; the AD conversion part includes multiple first AD acquisition chips, a first single-chip microcomputer, a first RS232 chip, multiple horizontal slide switches, multiple first instrument amplifiers, and multiple first resistors; each of the first AD acquisition chips is connected to a power input signal through a horizontal slide switch, a first instrument amplifier and a first resistor. channel; the first AD acquisition chips are electrically connected to the input end of the first single-chip microcomputer, and the output end of the first single-chip microcomputer is electrically connected to the first RS232 chip; the verification station part includes a second AD acquisition chip, a second single-chip microcomputer, a second RS232 chip, and a second instrument amplifier; the second AD acquisition chip is electrically connected to the voltage input signal channel through the second instrument amplifier, the second AD acquisition chip is electrically connected to the input end of the second single-chip microcomputer, and the output end of the second single-chip microcomputer is electrically connected to the second RS232 chip; the voltage value output by the digital control power supply is controlled by the second single-chip microcomputer, and the first RS232 chip is electrically connected to the second RS232 chip.

[0005] In a further embodiment of the present invention, the second single chip is electrically connected to a liquid crystal screen, a power switch of an AD conversion part, a power switch of a verification station part, and a verification button.

[0006] In a further embodiment of the present invention, the first resistor is a 200Ω resistor with a precision of 1 part in 10,000.

[0007] In a further embodiment of the present invention, the slide switch is used for switching voltage and current input; when the slide switch is disconnected, the voltage is directly input to the first instrument amplifier, and when the slide switch is on, the current 4-20mA passes through a 200Ω resistor and is converted into a voltage of 0.8-4V.

[0008] In a further embodiment of the present invention, the power input signal channels include eight power input signal channels IN0+ / IN0- to IN7+ / IN7-.

[0009] In a further embodiment of the present invention, the voltage input by the eight power input signal channels or the voltage converted from the current passes through the first instrument amplifier to the first AD acquisition chip, and AD acquisition is performed under the control of the first single-chip microcomputer.

[0010] An embodiment of the present invention further provides a fast correction method for a multi-channel high-precision AD acquisition correction circuit, characterized in that it comprises the following steps:

[0011] S0. Before calibration, ensure that the AD acquisition accuracy of the calibration bench is manually calibrated so that the error is less than 0.05%.

[0012] S1. Electrically connect the voltage output by the digital control power supply of the calibration table part to the eight power supply input signal channels from IN0+ / IN0- to IN7+ / IN7- of the AD conversion part and the voltage channel U+ / U- of the calibration table part, and turn the horizontal switch of the AD conversion part to the disconnected state;

[0013] S2, connecting the second RS232 chip of the serial port of the verification station part to the first RS232 chip of the serial port of the AD conversion part;

[0014] S3, turn on the power switch of the AD conversion part and the power switch of the calibration station part;

[0015] S4. Press the calibration button on the calibration table to start the calibration process;

[0016] S5. The check station sends the protocol 0XFE 0XFE 0X27 0X10 and the check code, 0X2710=10000, and sends the default coefficient 10000 to the AD conversion part; after receiving it, the AD conversion part saves it and replies with 0XFE 0XFE 0X27 0X10 and the check code;

[0017] S6, after the verification station part and the AD conversion part respond successfully, the verification station part controls the CNC power supply to segment the voltage according to 0.3V each section, and is divided into 0-0.3V, 0.3-0.6V, 0.6-0.9V, 0.9-1.2V, 1.2-1.5V, 1.5-1.8V, 1.8-2.1V, 2.1-2.4V, 2.4-2.7V, 2.7-3.0V, 3.0-3.3V, 3.3-3.6V, 3.6-3.9V, 3.9-4.2V, 4.2-4.5V, 4.5-4.8V, 4.8-5.0V, which are 0-16 voltage sections, and a value less than the upper limit is selected for voltage output at each 0.3V interval;

[0018] S7, after the calibration station outputs a voltage, it delays 300ms, sends 0xFE 0x F1 channel number (0x 00-0x07) and calibration code, and reads the calculated values ​​of the AD conversion part in sequence;

[0019] S8. After the AD conversion part receives the above command, the first single-chip computer program calculates the voltage of the first AD acquisition chip and sends 0xFE 0xF2 channel number (0x 00-0x 07) calculation value and check code;

[0020] S9, after receiving the calculated value from the AD conversion part, the calibration station calculates the corrected K value;

[0021] S10, after the calibration station calculates the K value of each channel and automatically determines the voltage segment to which it belongs, it sends the revised K value protocol: 0xFE 0xF3 channel number (0x 00-0x 07) segment number (0x 0-0x 16) K value and check code; after the AD conversion part receives the protocol, it saves the revised K value of the segment into the EEPROM of the first single-chip computer and sends a reply protocol: 0xFE0xF3 channel number (0x 00-0x 07) segment number (0x 0-0x 16) K value and check code;

[0022] S11, and so on, after the voltage output verification of the 0th stage is completed, the 1st stage will be automatically continued in the same way until all voltage outputs of 0-16 stages are verified;

[0023] S12, after the AD conversion part is powered on again, the corrected K value of the EEPROM is read out, so that the first single-chip computer program obtains a voltage value with a resolution of 0.1mv and an error of less than one thousandth according to the internal algorithm, thereby achieving high-precision calculation.

[0024] In a further embodiment of the present invention, in the step S8 and step S12, in the AD conversion part, in the programming of the first single chip, the voltage calculation value is obtained by the following algorithm, U 计算=AD acquisition value*5*K / 2 n ; Where n is the number of bits collected by AD; K is the correction coefficient, the default value is 10000.

[0025] In a further embodiment of the present invention, in step S9, when calculating the corrected K value, the voltage standard value calculated by the calibration station is U 校准 The calculated value returned by the AD conversion part is U 计算 ; then K=U 校准 *10000 / U 计算 .

[0026] The beneficial effects of the above technical solution of the present invention are as follows: the multi-channel high-precision AD chip correction circuit of the present invention includes an AD conversion part and a verification table part. The AD conversion part is electrically connected to the verification table part, and the AD conversion part is verified to obtain the correction coefficient K value of each voltage segment, thereby ensuring the high precision of the AD conversion part. At the same time, the use of this circuit structure for correction reduces the time-consuming manual correction, and has higher accuracy, is suitable for batch correction, and is more convenient.

[0027] The fast correction method of the present invention is based on a multi-channel high-precision AD chip correction circuit for correction. This correction method performs correction through simple operations of the verification station part combined with a simple algorithm in the single-chip microcomputer, realizes high-precision calculation, and obtains a more accurate correction value, thereby ensuring the high precision of the AD chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a circuit structure block diagram of the present invention;

[0029] Figure 2 A signal acquisition circuit diagram of a first AD acquisition chip in the AD conversion part of the present invention;

[0030] Figure 3 A circuit diagram of a first single chip microcomputer of an AD conversion part of the present invention;

[0031] Figure 4 A circuit diagram of the first RS232 chip and the second RS232 chip in the present invention;

[0032] Figure 5 A circuit diagram of the second single-chip microcomputer in the present invention used as a calibration single-chip microcomputer and a digital control power supply;

[0033] Figure 6 A circuit diagram of a second single-chip microcomputer signal processing part input in the verification station part of the present invention;

[0034] Figure 7 It is a circuit diagram of the related buttons and liquid crystal screen in the present invention. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0036] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "front", "back" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] like Figure 1As shown, a multi-channel high-precision AD chip correction circuit includes an AD conversion part and a calibration table part; the calibration table part includes a digital control power supply, which provides multiple power input signal channels for the AD conversion part and provides a voltage input signal channel for the calibration table; the AD conversion part includes multiple first AD acquisition chips, a first single-chip microcomputer, a first RS232 chip, multiple horizontal slide switches, multiple first instrument amplifiers, and multiple first resistors; each of the first AD acquisition chips is connected to a power input signal channel through a horizontal slide switch, a first instrument amplifier, and a first resistor; multiple first AD The acquisition chip is electrically connected to the input end of the first single-chip microcomputer, and the output end of the first single-chip microcomputer is electrically connected to the first RS232 chip; the verification station part includes a second AD acquisition chip, a second single-chip microcomputer, a second RS232 chip, and a second instrument amplifier; the second AD acquisition chip is electrically connected to the voltage input signal channel through the second instrument amplifier, the second AD acquisition chip is electrically connected to the input end of the second single-chip microcomputer, and the output end of the second single-chip microcomputer is electrically connected to the second RS232 chip; the voltage value output by the digital control power supply is controlled by the second single-chip microcomputer, and the first RS232 chip is electrically connected to the second RS232 chip. Specifically, the first AD acquisition chip and the second AD acquisition chip AD acquisition chip can use dual-channel AD7705, ADS1212U, etc.; the first instrument amplifier and the second instrument amplifier can use IN128; the first single-chip microcomputer and the second single-chip microcomputer use STC12C5A32S2. First, the verification station part is calibrated to high precision by a professional organization. In this case, the data of the verification station part is assumed to be accurate, and then the calculated value of the AD conversion part is compared with the data collected by the verification station part, K=U 校准 *10000 / U 计算 The K value is obtained. For example, if the data measured by the calibration bench is 3V and the data tested by the AD board is 2.98V, it means that the original coefficient 10000 is biased. Replace it with the new K and the calculation is also 3V.

[0039] Specifically, the second single-chip microcomputer is electrically connected to a liquid crystal screen, an AD conversion part power switch, a verification table part power switch, and a verification button. The liquid crystal screen, the AD conversion part power switch, the verification table part power switch, and the verification button are electrically connected to different input ports of the second single-chip microcomputer respectively, the AD conversion part power switch and the verification table part power switch respectively control the power supply of the AD conversion part and the verification table part, and the verification button is used to control whether to start the verification; the liquid crystal screen is used to display the verification result.

[0040] Specifically, the first resistor is a 200Ω resistor with a precision of 1 part per ten thousand.

[0041] Specifically, the slide switch is used for switching voltage and current input; when the slide switch is off, the voltage is directly input to the first instrument amplifier, and when the slide switch is on, the 4-20mA current passes through the 200Ω resistor and is converted into a 0.8-4V voltage.

[0042] Specifically, the power input signal channels include eight power input signal channels from IN0+ / IN0- to IN7+ / IN7-.

[0043] Specifically, the voltage input by the eight power input signal channels or the voltage converted from the current passes through the first instrument amplifier to the first AD acquisition chip, and AD acquisition is performed under the control of the first single-chip microcomputer.

[0044] like Figures 2 to 7 FIG. 1 is a specific circuit of an embodiment of the present invention. Figure 2 In the example, one of the power input signal channels is connected to the digital control power chip TLC5615 through the terminal J1. The first instrument amplifier uses the INA128 chip, and the first AD acquisition chip uses the single-channel digital-to-analog converter LTC1864IS8 chip. The first single-chip microcomputer uses the STC12C5A60S2-48. The circuit connection relationship is as follows: Figure 3 As shown; the electrical connection relationship between the first RS232 chip and the second RS232 chip is as shown Figure 4 As shown, the first RS232 chip and the second RS232 chip both use Max232; the second single-chip microcomputer is used as a calibration single-chip microcomputer and a digital control power supply as shown in FIG. Figure 5 As shown, the second single-chip microcomputer uses STC12C5A60S2-48, and the digital control power supply uses the chip TLC5615; in the calibration station part, the signal input is connected from the digital control power supply chip TLC5615, and provides a GND signal for the AD conversion part, and is amplified by the second instrument amplifier. The second instrument amplifier uses the INA128 chip. After the signal is amplified, it is input to the second single-chip microcomputer STC12C5A60S2-48. Specifically, Figure 6 As shown; in a specific embodiment of the present invention, the connection method of the relevant buttons and the LCD screen is as follows Figure 7 shown.

[0045] An embodiment of the present invention also provides a fast correction method for a multi-channel high-precision AD chip correction circuit, comprising the following steps:

[0046] S0. Before calibration, ensure that the AD acquisition accuracy of the calibration bench is manually calibrated so that the error is less than 0.05%.

[0047] S1. Electrically connect the voltage output by the digital control power supply of the calibration table part to the eight power supply input signal channels from IN0+ / IN0- to IN7+ / IN7- of the AD conversion part and the voltage channel U+ / U- of the calibration table part, and turn the horizontal switch of the AD conversion part to the disconnected state;

[0048] S2, connecting the second RS232 chip of the serial port of the verification station part to the first RS232 chip of the serial port of the AD conversion part;

[0049] S3, turn on the power switch of the AD conversion part and the power switch of the calibration station part;

[0050] S4. Press the calibration button on the calibration table to start the calibration process;

[0051] S5. The check station sends the protocol 0XFE 0XFE 0X27 0X10 and the check code, 0X2710=10000, and sends the default coefficient 10000 to the AD conversion part; after receiving it, the AD conversion part saves it and replies with 0XFE 0XFE 0X27 0X10 and the check code;

[0052] S6, after the verification station part and the AD conversion part respond successfully, the verification station part controls the CNC power supply to segment the voltage according to 0.3V each section, and is divided into 0-0.3V, 0.3-0.6V, 0.6-0.9V, 0.9-1.2V, 1.2-1.5V, 1.5-1.8V, 1.8-2.1V, 2.1-2.4V, 2.4-2.7V, 2.7-3.0V, 3.0-3.3V, 3.3-3.6V, 3.6-3.9V, 3.9-4.2V, 4.2-4.5V, 4.5-4.8V, 4.8-5.0V, which are 0-16 voltage sections, and a value less than the upper limit is selected for voltage output at each 0.3V interval;

[0053] The specific sections are as follows:

[0054] Segment 0: 0.0-0.3V

[0055] Section 1: 0.3-0.6V

[0056] Section 2: 0.6-0.9V

[0057] Section 3: 0.9-1.2V

[0058] Section 4: 1.2-1.5V

[0059] Section 5: 1.5-1.8V

[0060] Section 6: 1.8-2.1V

[0061] Segment 7: 2.1-2.4V

[0062] Segment 8: 2.4-2.7V

[0063] Section 9: 2.7-3.0V

[0064] Section 10: 3.0-3.3V

[0065] Section 11: 3.3-3.6V

[0066] Section 12: 3.6-3.9V

[0067] Section 13: 3.9-4.2V

[0068] Section 14: 4.2-4.5V

[0069] Section 15: 4.5-4.8V

[0070] Section 16: 4.8-5.0V

[0071] S7, after the calibration station outputs a voltage, it delays 300ms, sends 0xFE 0x F1 channel number (0x 00-0x07) and calibration code, and reads the calculated values ​​of the AD conversion part in sequence;

[0072] S8. After the AD conversion part receives the above command, the first single-chip computer program calculates the voltage of the first AD acquisition chip and sends 0xFE 0xF2 channel number (0x 00-0x 07) calculation value and check code;

[0073] S9, after receiving the calculated value from the AD conversion part, the calibration station calculates the corrected K value;

[0074] S10, after the calibration station calculates the K value of each channel and automatically determines the voltage segment to which it belongs, it sends the revised K value protocol: 0xFE 0xF3 channel number (0x 00-0x 07) segment number (0x 0-0x 16) K value and check code; after the AD conversion part receives the protocol, it saves the revised K value of the segment into the EEPROM of the first single-chip computer and sends a reply protocol: 0xFE0xF3 channel number (0x 00-0x 07) segment number (0x 0-0x 16) K value and check code;

[0075] S11, and so on, the 0th stage voltage output verification is completed, and the 1st stage is continued in the same way until all the 0-16 stage voltage output verifications are completed;

[0076] S12, after the AD conversion part is powered on again, the corrected K value of the EEPROM is read out, so that the first single-chip computer program obtains a voltage value with a resolution of 0.1mv and an error of less than one thousandth according to the internal algorithm, thereby achieving high-precision calculation.

[0077] In a further embodiment of the present invention, in the step S8 and step S12, in the AD conversion part, in the programming of the first single chip, the voltage calculation value is obtained by the following algorithm, U 计算 =AD acquisition value*5*K / 2 n ; Where n is the number of bits collected by AD; K is the correction coefficient, the default value is 10000.

[0078] In a further embodiment of the present invention, in step S9, when calculating the corrected K value, the voltage standard value calculated by the calibration station is U 校准 The calculated value returned by the AD conversion part is U 计算 ; then K=U 校准 *10000 / U 计算 .

[0079] In a further embodiment of the present invention, in step S10, the protocol is 0xFE 0xF3 channel segment number calibration coefficient and check code.

[0080] According to the quick correction method of the present invention, the CNC power supply outputs 0-16 voltage segments, which are collected by the 8 AD chips AD0-AD7 and calculated by the first single-chip computer to obtain the calculated values ​​of the voltage signals collected by the 8 AD chips. The relationship between the standard value of the calibration station part and the calculated value of AD0-AD8 is shown in Table 1 below.

[0081] Table 1 U measured on the test bench in the voltage range 0-16 标准 U with AD0-AD8 计算

[0082]

[0083] From Table 1, we can see that there is a deviation between the calculated value of the AD conversion part and the standard value of the calibration station part. This deviation is calculated by K=U 校准 *10000 / U 计算 By using this calculation formula, the correction coefficients corresponding to the voltage range of AD0-AD7 in the 0-16 range can be obtained as shown in Table 2.

[0084] Table 2 Correction coefficients corresponding to AD0-AD7 in the 0-16 voltage range

[0085]

[0086] Substitute K0-K7 shown in Table 2 into the program design of the first single-chip computer, and the voltage calculation value is obtained by the following algorithm. The calculated value U 计算 =AD acquisition value*5*K / 2 n , so that after the AD conversion part is powered on again, the correction coefficient of the EEPROM is read out, thereby obtaining a standard voltage that matches the calibration station part.

[0087] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made, such as the value of resistance, isolation between the single-chip microcomputer and AD, AD chip selection, etc. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A multi-channel high-precision AD acquisition correction circuit, characterized in that: It includes an AD conversion part and a verification table part; the verification table part includes a digital control power supply, which provides multiple power input signal channels for the AD conversion part and provides a voltage input signal channel for the verification table; the AD conversion part includes multiple first AD acquisition chips, a first single-chip microcomputer, a first RS232 chip, multiple horizontal switches, multiple first instrument amplifiers, and multiple first resistors; each of the first AD acquisition chips is connected to a power input signal channel through a horizontal switch, a first instrument amplifier, and a first resistor; multiple first AD acquisition chips are electrically connected to the input end of the first single-chip microcomputer, and the output end of the first single-chip microcomputer is electrically connected to the first RS232 chip; the verification table part includes a second AD acquisition chip, a second single-chip microcomputer, a second RS232 chip, and a second instrument amplifier; the second AD acquisition chip is electrically connected to the voltage input signal channel through the second instrument amplifier, the second AD acquisition chip is electrically connected to the input end of the second single-chip microcomputer, and the output end of the second single-chip microcomputer is electrically connected to the second RS232 chip; the voltage value output by the digital control power supply is controlled by the second single-chip microcomputer, and the first RS232 chip is electrically connected to the second RS232 chip; A fast correction method for a multi-channel high-precision AD acquisition correction circuit includes the following steps: S0. Before calibration, ensure that the AD acquisition accuracy of the calibration station is manually calibrated to make the error less than 0.05%; S1. Electrically connect the voltage output by the digital control power supply of the calibration table part to the eight power supply input signal channels from IN0+ / IN0- to IN7+ / IN7- of the AD conversion part and the voltage channel U+ / U- of the calibration table part, and turn the horizontal switch of the AD conversion part to the disconnected state; S2, connecting the second RS232 chip of the serial port of the verification station part to the first RS232 chip of the serial port of the AD conversion part; S3, turn on the power switch of the AD conversion part and the power switch of the calibration station part; S4. Press the calibration button on the calibration table to start the calibration process; S5. The check station sends the protocol 0XFE 0XFE 0X27 0X10 and the check code, 0X2710=10000, and sends the default coefficient 10000 to the AD conversion part; after receiving it, the AD conversion part saves it and replies with 0XFE 0XFE 0X27 0X10 and the check code; S6, after the verification station part and the AD conversion part respond successfully, the verification station part controls the CNC power supply to segment the voltage according to 0.3V each section, and is divided into 0-0.3V, 0.3-0.6V, 0.6-0.9V, 0.9-1.2V, 1.2-1.5V, 1.5-1.8V, 1.8-2.1V, 2.1-2.4V, 2.4-2.7V, 2.7-3.0V, 3.0-3.3V, 3.3-3.6V, 3.6-3.9V, 3.9-4.2V, 4.2-4.5V, 4.5-4.8V, 4.8-5.0V, which are 0-16 voltage sections, and a value less than the upper limit is selected for voltage output at each 0.3V interval; S7, after the calibration station outputs a voltage, it delays 300ms, sends the channel number and calibration code, and reads the calculated values ​​of the AD conversion part in sequence; S8, after the AD conversion part receives the channel number and the check code sent in step S7, the first single-chip computer program calculates the voltage of the first AD acquisition chip and sends the calculated value of the channel number and the check code; S9, after receiving the calculated value from the AD conversion part, the calibration station calculates the corrected K value; S10, after the calibration station calculates the K value of each channel and automatically determines the voltage segment to which it belongs, it sends a revised K value protocol; after the AD conversion part receives the protocol, it saves the revised K value of the segment into the EEPROM of the first single-chip computer and sends a reply protocol; S11, and so on, after the voltage output verification of the 0th stage is completed, the 1st stage will be automatically continued in the same way until all voltage outputs of 0-16 stages are verified; S12, after the AD conversion part is powered on again, the corrected K value of the EEPROM is read out, so that the first single-chip computer program obtains a voltage value with a resolution of 0.1mv and an error of less than one thousandth according to the internal algorithm, thereby achieving high-precision calculation.

2. A multi-channel high-precision AD acquisition correction circuit according to claim 1, characterized in that: The second single chip is electrically connected to the liquid crystal screen, the power switch of the AD conversion part, the power switch of the verification station part, and the verification button.

3. A multi-channel high-precision AD acquisition correction circuit according to claim 1, characterized in that: The first resistor is a 200Ω resistor with a 1 / 10,000 accuracy.

4. A multi-channel high-precision AD acquisition correction circuit according to claim 1, characterized in that: The slide switch is used for switching voltage and current input; when the slide switch is off, the voltage is directly input to the first instrument amplifier, and when the slide switch is on, the 4-20mA current passes through the 200Ω resistor and is converted into a 0.8-4V voltage.

5. The multi-channel high-precision AD acquisition correction circuit according to claim 1, characterized in that: The power input signal channels include eight power input signal channels from IN0+ / IN0- to IN7+ / IN7-.

6. A multi-channel high-precision AD acquisition correction circuit according to claim 5, characterized in that: The voltage input by the 8 power input signal channels or the voltage converted from the current passes through the first instrument amplifier to the first AD acquisition chip, and AD acquisition is performed under the control of the first single-chip microcomputer.

7. The fast correction method of a multi-channel high-precision AD acquisition correction circuit according to claim 1, characterized in that: In the step S8 and step S12, in the AD conversion part, in the programming of the first single chip, the voltage calculation value is obtained by the following algorithm, U 计算 =AD acquisition value*5*K / 2 n ; Where n is the number of bits collected by AD; K is the correction coefficient, the default value is 10000.

8. The fast correction method of a multi-channel high-precision AD acquisition correction circuit according to claim 7, characterized in that: In step S9, when calculating the corrected K value, the voltage standard value calculated by the calibration station is U 校准 The calculated value returned by the AD conversion part is U 计算 ; then K=U 校准 *10000 / U 计算 .

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