A multi-channel acquisition device

Abstract

The utility model discloses a kind of multi-channel acquisition devices, comprising: analog quantity type selection circuit, signal conditioning circuit, analog quantity channel selection circuit, conversion circuit, isolation circuit, controller and display;The output end of analog quantity type selection circuit is connected with the input end of signal conditioning circuit;The output end of signal conditioning circuit is connected with the input end of analog quantity channel selection circuit;The output end of analog quantity channel selection circuit is connected with the input end of isolation circuit by conversion circuit;The output end of isolation circuit is connected with controller;Controller is connected with the control end of analog quantity type selection circuit and the control end of analog quantity channel selection circuit by isolation circuit respectively, to realize electrical isolation;Controller is connected with display, and is used to carry out analog quantity type selection and analog quantity channel selection control on display.The utility model is through optimization circuit design and control logic, to solve the problems, such as poor signal adaptability, weak anti-interference ability and low channel switching efficiency in prior art.

Description

Technical Field

[0001] This utility model relates to the field of industrial automation control and data acquisition technology, specifically to a multi-channel acquisition device. Background Technology

[0002] In modern industrial automation, power monitoring, medical equipment, and environmental monitoring, multi-channel data acquisition systems are widely used for real-time monitoring of various analog signals (such as voltage, current, temperature, and pressure). Due to significant differences in the types and ranges of analog signals output by different sensors (such as 0–5V voltage, 4–20mA current, and thermocouple signals), traditional acquisition devices typically require dedicated conditioning circuits for specific signal types, resulting in poor system flexibility and high expansion costs. Furthermore, industrial environments often present problems such as electromagnetic interference and ground loop noise, which can affect acquisition accuracy and even damage downstream control circuits.

[0003] In existing technologies, some multi-channel acquisition devices employ fixed signal conditioning and channel switching schemes, which are difficult to adapt to various sensor types and lack effective electrical isolation measures, resulting in insufficient system reliability. Other schemes, while supporting multiple types of signal input, rely on complex programmable gain amplifiers (PGAs) or independent analog-to-digital converters (ADCs), leading to high hardware costs and complex channel switching and isolation control logic.

[0004] Therefore, there is an urgent need for an integrated and highly flexible multi-channel acquisition device that can achieve automatic adaptation, high-precision conditioning, configurable channel switching, and electrical isolation of various types of analog signals through the collaborative design of hardware circuits and software control, while reducing system complexity and cost. Utility Model Content

[0005] In order to overcome the technical shortcomings of traditional acquisition devices that typically only support single or fixed types of analog signals and cannot flexibly adapt to signals output by different sensors, this utility model provides a multi-channel acquisition device.

[0006] To solve the above problems, this utility model is implemented according to the following technical solution:

[0007] The multi-channel acquisition device of this utility model includes: an analog signal type selection circuit, a signal conditioning circuit, an analog signal channel selection circuit, a conversion circuit, an isolation circuit, a controller, and a display. The output terminal of the analog signal type selection circuit is connected to the input terminal of the signal conditioning circuit. The output terminal of the signal conditioning circuit is connected to the input terminal of the analog signal channel selection circuit. The output terminal of the analog signal channel selection circuit is connected to the input terminal of the isolation circuit through the conversion circuit. The output terminal of the isolation circuit is connected to the controller. The controller is connected to the control terminal of the analog signal type selection circuit and the control terminal of the analog signal channel selection circuit through the isolation circuit to achieve electrical isolation. The controller is connected to the display and is used to perform analog signal type selection and analog signal channel selection control on the display.

[0008] Preferably, the analog signal type selection circuit includes an input terminal, a bidirectional trigger diode, a first capacitor, a first resistor, an optocoupler relay, a first diode, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a second diode, a third diode, a fourth diode, a fifth diode, and an instrumentation amplifier; the input terminal includes a first port and a second port, the first port being connected to one end of the bidirectional trigger diode and one end of the first capacitor, and the second port being connected to the other end of the bidirectional trigger diode and the other end of the first capacitor; the third pin of the optocoupler relay is connected to one end of the first capacitor, the fourth pin of the optocoupler relay is connected to the other end of the first capacitor through the first resistor, the second pin of the optocoupler relay is connected to the positive terminal of the first diode and one end of the second resistor, the first pin of the optocoupler is connected to the negative terminal of the first diode and the other end of the second resistor; one end of the third resistor is connected to the first pin of the optocoupler, and the other end of the third resistor is connected to an AC / DC converter; the instrumentation amplifier... The non-inverting input of the instrumentation amplifier is connected to the third pin of the optocoupler relay through the fourth resistor. The inverting input of the instrumentation amplifier is connected to the other end of the first capacitor through the fifth resistor. The first gain setting terminal of the instrumentation amplifier is connected to the second gain setting terminal of the instrumentation amplifier through the fifth resistor. The positive power supply terminal of the instrumentation amplifier is connected to a positive 12V power supply, the negative power supply terminal of the instrumentation amplifier is connected to a negative 12V power supply, the reference terminal of the instrumentation amplifier is connected to ground, and the output terminal of the instrumentation amplifier is connected to the signal conditioning circuit. The anode of the second diode is connected to a negative 12V power supply, and the cathode of the second diode is connected to the non-inverting input of the instrumentation amplifier. The cathode of the third diode is connected to a positive 12V power supply, and the anode of the third diode is connected to the non-inverting input of the instrumentation amplifier. The cathode of the fourth diode is connected to a positive 12V power supply, and the anode of the fourth diode is connected to the inverting input of the instrumentation amplifier. The anode of the fifth diode is connected to a negative 12V power supply, and the cathode of the fifth diode is connected to the inverting input of the instrumentation amplifier.

[0009] Preferably, the signal conditioning circuit includes a first operational amplifier circuit and a second operational amplifier circuit; the input terminal of the first operational amplifier circuit is connected to the output terminal of the analog signal type selection circuit; the input terminal of the second operational amplifier circuit is connected to the output terminal of the first operational amplifier circuit, and the output terminal of the second operational amplifier circuit is connected to the input terminal of the analog signal channel selection circuit.

[0010] Preferably, the first operational amplifier circuit includes a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a first operational amplifier, a second capacitor, and a third capacitor; one end of the sixth resistor is connected to the output terminal of the instrumentation amplifier, and the other end of the sixth resistor is connected to the output terminal of the first operational amplifier through the second capacitor; one end of the seventh resistor is connected to the other end of the sixth resistor, and the other end of the seventh resistor is connected to the non-inverting input terminal of the first operational amplifier; one end of the third capacitor is connected to the non-inverting input terminal of the first operational amplifier, and the other end of the third capacitor is connected to ground; one end of the eighth resistor is connected to ground, and the other end of the eighth resistor is connected to the inverting input terminal of the first operational amplifier; the output terminal of the first operational amplifier is connected to the inverting input terminal of the first operational amplifier through the ninth resistor; the positive power supply terminal of the first operational amplifier is connected to a positive 12V power supply, and the negative power supply terminal of the first operational amplifier is connected to a negative 12V power supply.

[0011] Preferably, the second operational amplifier circuit includes a tenth resistor, an eleventh resistor, a twelfth resistor, and a second operational amplifier; the non-inverting input terminal of the second operational amplifier is connected to the first operational amplifier circuit through the tenth resistor; one end of the eleventh resistor is connected to ground, and the other end of the eleventh resistor is connected to the inverting input terminal of the second operational amplifier; the output terminal of the second operational amplifier is connected to the inverting input terminal of the second operational amplifier through the twelfth resistor; the positive power supply terminal of the second operational amplifier is connected to a positive 12V power supply, and the negative power supply terminal of the second operational amplifier is connected to a negative 12V power supply; the output terminal of the second operational amplifier is connected to the analog quantity type selection circuit.

[0012] Preferably, the analog channel selection circuit includes a data selector, a fourth capacitor, a thirteenth resistor, a fourteenth resistor, a first optocoupler, a fifteenth resistor, a sixteenth resistor, a second optocoupler, a seventeenth resistor, an eighteenth resistor, and a third optocoupler; the VDD terminal of the data selector is connected to the VSS terminal of the data selector through the fourth capacitor; the VDD terminal, the VEE terminal, and the INH terminal of the data selector are all connected to ground; the VSS terminal of the data selector is connected to 5V; and the COM terminal of the data selector... The OUT / IN terminals are connected to the conversion circuit; the EN terminal of the first optocoupler is connected to the A terminal of the data selector and the output terminal of the first optocoupler through the thirteenth resistor, the C terminal of the first optocoupler is connected to the controller through the fourteenth resistor, the GND terminal of the first optocoupler is connected to ground, the A terminal of the first optocoupler is connected to a 3.3V power supply, and both the EN terminal and the VCC terminal of the first optocoupler are connected to a 5V power supply; the EN terminal of the second optocoupler is connected to the B terminal of the data selector and the output terminal of the second optocoupler through the fifteenth resistor, and the C terminal of the second optocoupler is connected to the controller through the fourteenth resistor. A sixteen-resistor is connected to the controller. The GND terminal of the second optocoupler is connected to ground. The A terminal of the second optocoupler is connected to a 3.3V power supply. The EN terminal and VCC terminal of both the second and second optocouplers are connected to a 5V power supply. The EN terminal of the third optocoupler is connected to the C terminal of the data selector and the output terminal of the third optocoupler through the seventeenth resistor. The C terminal of the third optocoupler is connected to the controller through the eighteenth resistor. The GND terminal of the third optocoupler is connected to ground. The A terminal of the third optocoupler is connected to a 3.3V power supply. The EN terminal and VCC terminal of the third optocoupler are both connected to a 5V power supply.

[0013] Preferably, the first optocoupler, the second optocoupler, and the third optocoupler are used to achieve electrical isolation between the input signal and the analog channel selection circuit.

[0014] Preferably, the conversion circuit includes an ADC chip; the AVCC terminal of the ADC chip is connected to a 5V power supply; the AGND terminal, AGND1 terminal, REFGND1 terminal, and REFGND2 terminal of the ADC chip are all connected to ground.

[0015] Preferably, the conversion circuit further includes a fifth capacitor, a sixth capacitor, a seventh capacitor, and an eighth capacitor; the REFCAPB terminal of the ADC chip and the REFCAPB terminal of the ADC chip are both connected to the AGND1 terminal of the ADC chip through the fifth capacitor; the REFCAP2 terminal of the ADC chip is connected to the AGND1 terminal of the ADC chip through the sixth capacitor; the REFIN / REFOUT terminal of the ADC chip is connected to the AGND1 terminal of the ADC chip through the seventh capacitor; the REFCAP1 terminal of the ADC chip is connected to the AGND1 terminal of the ADC chip through the eighth capacitor; the fifth, sixth, seventh, and eighth capacitors are used for filtering and decoupling of the power supply and reference voltage.

[0016] Preferably, the controller is a programmable gate array (PGA) chip.

[0017] Compared with the prior art, the beneficial effects of this utility model are:

[0018] The multi-channel acquisition device provided by this invention effectively solves the problems of poor signal adaptability, weak anti-interference capability, and low channel switching efficiency in existing technologies by optimizing circuit design and control logic. The device uses an analog signal type selection circuit that can automatically adapt to various sensor signals (such as voltage, current, thermocouples, RTDs, etc.) without manual hardware adjustment. Combined with a signal conditioning circuit that can dynamically adjust gain, filtering, and bias, it ensures that various signals accurately match the ADC range, significantly improving measurement accuracy and system flexibility. It innovatively adopts a full-link isolation design, effectively blocking ground loop noise, high-voltage crosstalk, and electromagnetic interference through high-performance isolation circuits, protecting the controller's safe operation. At the same time, the isolated control architecture avoids common ground interference problems. The device uses an analog signal channel selection circuit to achieve fast, low-loss channel switching. Combined with isolation control technology, it effectively suppresses crosstalk between channels, ensuring the independence and accuracy of multi-channel signal sampling. Through a highly integrated signal conditioning circuit, analog signal channel selection circuit, conversion circuit, and isolation circuit architecture, the number of discrete components is significantly reduced, not only shrinking the PCB area but also lowering power consumption and BOM costs. The design employs a universal conversion circuit and signal conditioning circuit, avoiding the need for separate hardware development for different signal types, thus improving both cost-effectiveness and system scalability. The device exhibits excellent adaptability to industrial environments; its modular architecture maintains stable operation even under harsh conditions such as strong electromagnetic interference, high humidity, and high vibration, while also facilitating maintenance and upgrades, effectively extending the equipment's lifespan. Attached Figure Description

[0019] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings, wherein:

[0020] Figure 1This is a schematic diagram of a multi-channel acquisition device according to this utility model.

[0021] Figure 2 This is the analog quantity type selection circuit diagram of this utility model.

[0022] Figure 3 This is the signal conditioning circuit diagram of this utility model.

[0023] Figure 4 This is the analog channel selection circuit diagram of this utility model.

[0024] Figure 5 This is the conversion circuit diagram of this utility model.

[0025] In the diagram: 1-Analog signal type selection circuit, 2-Signal conditioning circuit, 21-First operational amplifier circuit, 22-Second operational amplifier circuit, 3-Analog signal channel selection circuit, 4-Conversion circuit, 5-Isolation circuit, 6-Controller, 7-Display. Detailed Implementation

[0026] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0027] In existing technologies, multi-channel data acquisition systems need to process various analog signal types, but traditional devices typically use fixed conditioning circuits, making it difficult to adapt to different sensor outputs. Industrial environments are plagued by electromagnetic interference and ground loop noise, and existing solutions lack effective isolation measures, affecting acquisition accuracy and system reliability. Some solutions supporting multiple input types rely on complex hardware structures, resulting in high costs and cumbersome control logic, failing to meet flexibility and cost-effectiveness requirements. To address these issues, the first step is to solve the problem of adapting to multiple signal types, considering the use of configurable circuits to automatically match different sensor outputs. To address interference, isolation structures are proposed at key nodes to block noise propagation paths. To reduce system complexity, a centralized control strategy coordinates channel switching and signal conditioning processes. Modular design integrates signal selection, conditioning, and conversion functions, reducing redundant circuits and optimizing hardware resource utilization.

[0028] like Figures 1-5 As shown, this utility model discloses a preferred structure of a multi-channel acquisition device.

[0029] Example 1

[0030] like Figure 1As shown, the multi-channel acquisition device of this utility model includes: an analog signal type selection circuit 1, a signal conditioning circuit 2, an analog signal channel selection circuit 3, a conversion circuit 4, an isolation circuit 5, a controller 6, and a display 7. The output terminal of the analog signal type selection circuit 1 is connected to the input terminal of the signal conditioning circuit 2. The output terminal of the signal conditioning circuit 2 is connected to the input terminal of the analog signal channel selection circuit 3. The output terminal of the analog signal channel selection circuit 3 is connected to the input terminal of the isolation circuit 5 through the conversion circuit 4. The output terminal of the isolation circuit 5 is connected to the controller 6. The controller 6 is connected to the control terminal of the analog signal type selection circuit 1 and the control terminal of the analog signal channel selection circuit 3 through the isolation circuit 5 to achieve electrical isolation. The controller 6 is connected to the display 7 and is used to perform analog signal type selection and analog signal channel selection control on the display 7.

[0031] The analog signal type selection circuit 1 is a circuit that automatically switches the matching path based on the characteristics of the input signal (voltage / current / thermocouple / RTD, etc.). Specifically, it can be implemented using a combination structure including an optocoupler relay and an instrumentation amplifier. The relay switches between different input impedance networks, and the amplifier adjusts the signal amplitude range. The signal conditioning circuit 2 amplifies and filters the selected signal. Specifically, it can be implemented using an active filter circuit composed of two operational amplifier stages; the first stage performs impedance matching, and the second stage performs gain adjustment. The analog signal channel selection circuit 3 enables time-division multiplexing of multiple signals. Specifically, it can be implemented using a data selector in conjunction with an optocoupler, switching physical channels while maintaining electrical isolation via digital control signals. The isolation circuit 5 blocks the direct connection between the signal ground and the control ground. Specifically, it can be implemented using opto-isolation devices or magnetic isolation modules to eliminate the impact of common-mode interference on the controller 6.

[0032] Specifically, the input signal first enters the analog signal type selection circuit 1, where the input impedance and measurement range are automatically matched according to the sensor type. After preliminary processing, the signal enters the signal conditioning circuit 2 for amplification and noise suppression, forming a standardized signal that meets the requirements of analog-to-digital conversion. The conditioned signal is then transmitted to the analog signal channel selection circuit 3, where the controller 6 sends a channel selection command through the isolation circuit 5, controlling the data selector to switch the target channel. The analog signal of the selected channel is converted into a digital signal by the conversion circuit 4 and then transmitted to the controller 6 through the isolation circuit 5 for data processing. Finally, the acquisition results are displayed in real time on the display 7. Throughout the process, the isolation circuit 5 forms a double isolation barrier on both the signal and control paths, ensuring electrical safety between the high-voltage and low-voltage sides.

[0033] Preferably, such as Figure 2As shown, the analog signal type selection circuit 1 includes an input terminal, a bidirectional trigger diode, a first capacitor, a first resistor, an optocoupler relay, a first diode, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a second diode, a third diode, a fourth diode, a fifth diode, and an instrumentation amplifier. The input terminal includes a first port and a second port. The first port is connected to one end of the bidirectional trigger diode and one end of the first capacitor, respectively. The second port is connected to the other end of the bidirectional trigger diode and the other end of the first capacitor, respectively. The third pin of the optocoupler relay is connected to one end of the first capacitor. The fourth pin of the optocoupler relay is connected to the other end of the first capacitor through the first resistor. The second pin of the optocoupler relay is connected to the positive terminal of the first diode and one end of the second resistor, respectively. The first pin of the optocoupler is connected to the negative terminal of the first diode and the other end of the second resistor, respectively. One end of the third resistor is connected to the first pin of the optocoupler, and the other end of the third resistor is connected to an AC / DC converter. The instrumentation amplifier... The non-inverting input of the instrumentation amplifier is connected to the third pin of the optocoupler relay through the fourth resistor. The inverting input of the instrumentation amplifier is connected to the other end of the first capacitor through the fifth resistor. The first gain setting terminal of the instrumentation amplifier is connected to the second gain setting terminal of the instrumentation amplifier through the fifth resistor. The positive power supply terminal of the instrumentation amplifier is connected to a positive 12V power supply, and the negative power supply terminal of the instrumentation amplifier is connected to a negative 12V power supply. The reference terminal of the instrumentation amplifier is connected to ground. The output terminal of the instrumentation amplifier is connected to the signal conditioning circuit 2. The anode of the second diode is connected to a negative 12V power supply, and the cathode of the second diode is connected to the non-inverting input of the instrumentation amplifier. The cathode of the third diode is connected to a positive 12V power supply, and the anode of the third diode is connected to the non-inverting input of the instrumentation amplifier. The cathode of the fourth diode is connected to a positive 12V power supply, and the anode of the fourth diode is connected to the inverting input of the instrumentation amplifier. The anode of the fifth diode is connected to a negative 12V power supply, and the cathode of the fifth diode is connected to the inverting input of the instrumentation amplifier.

[0034] The input terminals receive external analog signals, such as voltage or current signals. A bidirectional trigger diode limits the input voltage amplitude to prevent overvoltage damage to subsequent circuits. The first capacitor filters out high-frequency noise, such as electromagnetic interference signals. The optocoupler relay controls the signal path through optical isolation, achieving electrical isolation between the input and output sides. The instrumentation amplifier amplifies differential signals, suppresses common-mode interference, and improves signal quality. Diodes two through five form an input protection network to limit the voltage range at the instrumentation amplifier's input, preventing damage from exceeding the power rail. The AC / DC converter provides isolated power to the optocoupler relay, isolating the control signal from the main power system.

[0035] Specifically, when an external analog signal is input to the input terminal, the bidirectional trigger diode automatically conducts according to the polarity of the input signal, limiting transient overvoltage. The first capacitor and the first resistor form a low-pass filter to filter out high-frequency noise. The controller 6 controls the signal path selection through the optocoupler relay, and the conduction state of the optocoupler relay is determined by the isolated control signal. The instrumentation amplifier differentially amplifies the selected signal, and its gain is set by the ratio of the fourth and fifth resistors. The second to fifth diodes clamp the voltage at the non-inverting and inverting input terminals respectively to prevent exceeding the ±12V power supply range. The AC / DC converter provides an independent power supply for the optocoupler relay, ensuring electrical isolation between the control side and the signal side. This application can adapt to various analog signal input types, such as 0-10V voltage or 4-20mA current signals, avoiding device damage caused by overvoltage or polarity reversal. The input protection network effectively suppresses transient interference, and the optocoupler relay and AC / DC converter work together to achieve complete electrical isolation between the signal path and the control system, reducing the impact of ground loop noise on the acquisition accuracy. The differential input structure of the instrumentation amplifier can eliminate common-mode interference and improve the stability of weak signal acquisition.

[0036] More specifically, when the input signal is a voltage signal (-10V to +10V), the voltage signal is connected to the input terminal, and resistor R1 is disconnected; when the input signal is a current signal (0 to 20mA) or (4 to 20mA), the analog selector needs to be controlled by controller 6 to select it as a current input. When it is an NTC resistor, it is directly connected to the input terminal, and resistor R1 is connected to one end of the bidirectional trigger diode.

[0037] Preferably, such as Figure 3 As shown, the signal conditioning circuit 2 includes a first operational amplifier circuit 21 and a second operational amplifier circuit 22; the input terminal of the first operational amplifier circuit 21 is connected to the output terminal of the analog signal type selection circuit 1; the input terminal of the second operational amplifier circuit 22 is connected to the output terminal of the first operational amplifier circuit 21, and the output terminal of the second operational amplifier circuit 22 is connected to the input terminal of the analog signal channel selection circuit 3.

[0038] The first operational amplifier circuit 21 is a pre-stage signal processing unit constructed from operational amplifiers, which can be implemented using an inverting or non-inverting amplifier structure. It is used for preliminary amplification and impedance matching of the input signal. The second operational amplifier circuit 22 is a post-stage signal processing unit constructed from operational amplifiers, which can be implemented using a voltage follower or a filter circuit. It is used to further adjust the signal amplitude and suppress high-frequency noise. The signal conditioning circuit 2 achieves step-by-step signal processing through a two-stage operational amplifier structure. The pre-stage is responsible for gain adjustment, and the post-stage is responsible for signal buffering and filtering, thereby avoiding the problem of single-stage amplifier circuits being susceptible to interference.

[0039] Specifically, the signal output from analog signal type selection circuit 1 first enters the first operational amplifier circuit 21 for baseline adjustment and primary amplification. The first operational amplifier circuit 21 sets the amplification factor through a resistor network; for example, when using an inverting amplification structure, the input signal is output after the ratio of the input resistor to the feedback resistor is adjusted. The signal after primary amplification is transmitted to the second operational amplifier circuit 22, which eliminates the load effect between the preceding and following stages by configuring it as a voltage follower, while simultaneously using built-in filter capacitors to filter out high-frequency interference signals. The signal after two stages of processing is finally output to analog signal channel selection circuit 3, ensuring that the signal before channel switching has sufficient amplitude stability and anti-interference capability. Analog signal type selection circuit 1 effectively solves the conditioning compatibility problem caused by the amplitude differences of signals from multiple types of sensors, improving signal linearity through staged processing. The cascaded filtering characteristics formed by the two-stage operational amplifier structure can suppress high-frequency interference in industrial environments and reduce the risk of signal crosstalk during channel switching. After two conditioning stages, the signal reaches the optimal input range of analog-to-digital converter circuit 4, thereby improving the overall acquisition accuracy.

[0040] Preferably, the first operational amplifier circuit 21 includes a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a first operational amplifier, a second capacitor, and a third capacitor; one end of the sixth resistor is connected to the output terminal of the instrumentation amplifier, and the other end of the sixth resistor is connected to the output terminal of the first operational amplifier through the second capacitor; one end of the seventh resistor is connected to the other end of the sixth resistor, and the other end of the seventh resistor is connected to the non-inverting input terminal of the first operational amplifier; one end of the third capacitor is connected to the non-inverting input terminal of the first operational amplifier, and the other end of the third capacitor is connected to ground; one end of the eighth resistor is connected to ground, and the other end of the eighth resistor is connected to the inverting input terminal of the first operational amplifier; the output terminal of the first operational amplifier is connected to the inverting input terminal of the first operational amplifier through the ninth resistor; the positive power supply terminal of the first operational amplifier is connected to a positive 12V power supply, and the negative power supply terminal of the first operational amplifier is connected to a negative 12V power supply.

[0041] The sixth resistor is an impedance matching component, its function being to match the impedance between the instrumentation amplifier output signal and the input terminal of the first operational amplifier, reducing signal reflection. The seventh resistor and the third capacitor form a low-pass filter network, used to filter out high-frequency noise. The eighth and ninth resistors form a feedback network that sets the amplification factor of the first operational amplifier; the amplification factor is controlled by adjusting the resistance ratio. The second capacitor is a filtering component in the feedback path, used to suppress high-frequency interference and stabilize the output signal.

[0042] Specifically, the signal output from the instrumentation amplifier is impedance matched by the sixth resistor, then filtered by a low-pass filter composed of the seventh resistor and the third capacitor to remove high-frequency noise, before being input to the non-inverting input of the first operational amplifier. The inverting input of the first operational amplifier is grounded through the eighth resistor and forms a negative feedback loop with the output through the ninth resistor, thereby determining the amplification factor. The second capacitor is connected between the sixth resistor and the output of the first operational amplifier to further suppress high-frequency interference. By using a dual power supply of ±12V, the first operational amplifier can process analog signals covering a range of positive and negative voltages, such as input signals from -10V to +10V. Traditional signal conditioning circuits 2 typically employ a single operational amplifier structure or a complex filter network, resulting in limited signal bandwidth or excessive circuit size. This signal conditioning circuit 2 achieves low-pass filtering through a simple combination of the seventh resistor and the third capacitor, while precisely controlling the gain using the feedback network of the eighth and ninth resistors, simplifying the circuit structure while ensuring signal quality. Furthermore, the parallel design of the second capacitor and the sixth resistor effectively absorbs high-frequency noise, avoiding the need for additional filter modules in traditional solutions. This circuit structure reduces hardware complexity while maintaining anti-interference capabilities and signal fidelity, making it suitable for industrial environments with electromagnetic interference.

[0043] Preferably, the second operational amplifier circuit 22 includes a tenth resistor, an eleventh resistor, a twelfth resistor, and a second operational amplifier; the non-inverting input terminal of the second operational amplifier is connected to the first operational amplifier circuit 21 through the tenth resistor; one end of the eleventh resistor is connected to ground, and the other end of the eleventh resistor is connected to the inverting input terminal of the second operational amplifier; the output terminal of the second operational amplifier is connected to the inverting input terminal of the second operational amplifier through the twelfth resistor; the positive power supply terminal of the second operational amplifier is connected to a positive 12V power supply, and the negative power supply terminal of the second operational amplifier is connected to a negative 12V power supply; the output terminal of the second operational amplifier is connected to the analog quantity type selection circuit 1.

[0044] The tenth resistor is used to achieve impedance matching between the first operational amplifier circuit 21 and the second operational amplifier, suppressing high-frequency noise during signal transmission. The eleventh and twelfth resistors are used to set the closed-loop gain of the second operational amplifier; the gain is adjustable by adjusting the resistor ratio. The second operational amplifier uses a dual-power supply mode, with its positive and negative power supply terminals connected to a positive 12V and a negative 12V power supply, respectively, supporting bidirectional signal conditioning, such as processing AC signals or DC signals containing negative voltage components. The twelfth resistor forms a negative feedback loop between the output terminal and the inverting input terminal of the second operational amplifier to stabilize the amplified signal amplitude.

[0045] Specifically, the second operational amplifier circuit 22 receives the pre-processed analog signal from the first operational amplifier circuit 21 and inputs the signal to the non-inverting input terminal of the second operational amplifier through the tenth resistor. The feedback network formed by the eleventh and twelfth resistors enables the second operational amplifier to operate in inverting amplification mode, and its closed-loop gain is determined by the ratio of the twelfth to the eleventh resistor. Dual power supply enables the second operational amplifier to process signals containing negative voltage components, such as in thermocouple signal or AC current signal conditioning scenarios, avoiding signal clipping distortion. The amplified signal is transmitted to the analog channel selection circuit 3 through the output terminal, where the resistance value of the twelfth resistor can be adjusted according to the sensor output range. For example, when a 4-20mA current signal is converted to a 0-5V voltage, the gain can be set to 0.25 times to adapt to the range of the subsequent ADC. This application achieves high-precision secondary amplification and level adaptation of analog signals, solving the range adaptation problem caused by the non-adjustable gain or limited signal range of traditional acquisition devices. The closed-loop negative feedback structure effectively suppresses gain drift caused by changes in ambient temperature. The dual-power supply design enables the system to be compatible with both positive and negative polarity signal inputs. For example, when acquiring ±10V AC signals from industrial vibration sensors, the signals can be directly amplified without the need for a signal isolation module. The configurable parameters of the resistor network support rapid adaptation to different sensor output characteristics. For instance, when switching between a pressure sensor and a temperature sensor, only the ratio of the eleventh and twelfth resistors needs to be adjusted to achieve range matching. After selection, the analog signal is converted into a ±10V voltage signal, which is then sampled with high precision by a three-op-amp topology instrumentation amplifier. This three-op-amp topology instrumentation amplifier achieves high input impedance, low output offset, and high-precision sampling; however, it uses unity gain, thus requiring a subsequent signal conditioning circuit. A two-stage filter circuit removes noise from the analog signal and is particularly suitable for small-signal filtering. After passing through the two-stage filter circuit, the signal is amplified to match the full-scale sampling of the ADC, further meeting the high-precision measurement requirements.

[0046] Preferably, such as Figure 4As shown, the analog channel selection circuit 3 includes a data selector, a fourth capacitor, a thirteenth resistor, a fourteenth resistor, a first optocoupler, a fifteenth resistor, a sixteenth resistor, a second optocoupler, a seventeenth resistor, an eighteenth resistor, and a third optocoupler. The VDD terminal of the data selector is connected to the VSS terminal of the data selector through the fourth capacitor. The VDD terminal, the VEE terminal, and the INH terminal of the data selector are all connected to ground. The VSS terminal of the data selector is connected to 5V. The COM terminal of the data selector... The OUT / IN terminals are connected to the conversion circuit 4; the EN terminal of the first optocoupler is connected to the A terminal of the data selector and the output terminal of the first optocoupler through the thirteenth resistor, the C terminal of the first optocoupler is connected to the controller 6 through the fourteenth resistor, the GND terminal of the first optocoupler is connected to ground, the A terminal of the first optocoupler is connected to a 3.3V power supply, and both the EN terminal and the VCC terminal of the first optocoupler are connected to a 5V power supply; the EN terminal of the second optocoupler is connected to the B terminal of the data selector and the output terminal of the second optocoupler through the fifteenth resistor, and the C terminal of the second optocoupler is connected to the controller 6 through the fourteenth resistor. A sixteen-resistor is connected to the controller 6. The GND terminal of the second optocoupler is connected to ground, the A terminal of the second optocoupler is connected to a 3.3V power supply, and the EN terminal and VCC terminal of both the second and second optocouplers are connected to a 5V power supply. The EN terminal of the third optocoupler is connected to the C terminal of the data selector and the output terminal of the third optocoupler through the seventeenth resistor. The C terminal of the third optocoupler is connected to the controller 6 through the eighteenth resistor. The GND terminal of the third optocoupler is connected to ground, the A terminal of the third optocoupler is connected to a 3.3V power supply, and the EN terminal and VCC terminal of the third optocoupler are both connected to a 5V power supply.

[0047] The data selector is an integrated circuit used for switching multiple signals, specifically implemented using a multiplexer, which selects a specific input channel via an address signal. The fourth capacitor is a filter capacitor connected between the power supply and ground, specifically implemented using a ceramic capacitor or electrolytic capacitor, used to suppress high-frequency noise. The optocoupler is a device that achieves isolated transmission of electrical signals, specifically using a combination of a phototransistor and a light-emitting diode, transmitting control signals via optical signals to avoid direct electrical connection. The resistor is a component that limits current or divides voltage, specifically implemented using a metal film resistor or carbon film resistor, used to set the operating current and signal level matching of the optocoupler.

[0048] Specifically, the data selector receives the address signal from controller 6 and selects the corresponding input channel through the state combination of the three address terminals A, B, and C. A fourth capacitor is connected in parallel between the power supply terminal and ground of the data selector to filter out power supply interference and ensure stable operation of the data selector. The first, second, and third optocouplers correspond to the three address terminals of the data selector, respectively. They drive LEDs via isolation control signals sent by controller 6. The phototransistor conducts after receiving the light signal, transmitting the logic level to the address input terminal of the data selector. Resistors thirteen, fifteen, and seventeen limit the current on the input side of the optocoupler to prevent overcurrent damage. Resistors fourteen, sixteen, and eighteen are connected between the output side of the optocoupler and controller 6 to convert the output current of the phototransistor into a voltage signal and match it with the input level of controller 6. Through the isolation effect of the optocouplers, electrical isolation is achieved between controller 6 and the data selector, avoiding ground loop interference from affecting signal selection accuracy. This solution transmits control signals via optocouplers, simultaneously achieving channel switching while severing the electrical connection path between controller 6 and the analog front-end, effectively suppressing the impact of common-mode noise and ground potential difference on signal selection. The combined design of the data selector and optocoupler simplifies the multi-channel switching logic, requiring only a few address lines to achieve multi-channel selection, thus reducing hardware complexity. To reduce cost, decrease the number of ADCs, and enable multi-analog signal acquisition, the analog channel selection circuit 3 uses an 8-to-1 analog switch for analog channel selection. The selection signal for channel selection is provided by controller 6, and this signal is first isolated by a high-speed optocoupler before being sent to the analog selection switch, achieving signal isolation and improving anti-interference capabilities.

[0049] Preferably, the first optocoupler, the second optocoupler, and the third optocoupler are used to achieve electrical isolation between the input signal and the analog channel selection circuit 3.

[0050] Among them, an optocoupler is a device that achieves electrical isolation between the input and output sides through optical signals. It can be implemented using an integrated device containing a light-emitting diode and a phototransistor, and its function is to block the direct electrical connection between the input signal and the downstream circuitry. A data selector is an integrated circuit used to switch multiple analog signal channels. It can be implemented using a multiplexer chip, and its function is to select the input signal for a specific channel based on a control signal. Resistors and capacitors are passive components used for current limiting, voltage division, and filtering. They can be implemented using surface-mount resistors and ceramic capacitors, and their function is to adjust the impedance characteristics of the signal transmission path and suppress high-frequency interference.

[0051] Specifically, when controller 6 sends a channel selection command to the data selector via the optocoupler, the internal LED of the optocoupler converts the electrical signal into an optical signal. The phototransistor receives the optical signal and regenerates the electrical signal, thereby achieving electrical isolation between the control signal and the analog channel. The data selector switches the corresponding input channel according to the received control signal, allowing the analog signal of the selected channel to be transmitted to the conversion circuit 4. During this process, the optocoupler blocks the common ground connection between the input signal path and the control signal path, preventing ground loop noise or voltage surges from being conducted to controller 6 through the control lines. For example, when common-mode interference exists in the input signal, the optocoupler can effectively isolate the direct impact of the interference signal on controller 6 while ensuring the accurate transmission of the channel switching command.

[0052] Preferably, such as Figure 5 As shown, the conversion circuit 4 includes an ADC chip; the AVCC terminal of the ADC chip is connected to a 5V power supply; the AGND terminal, AGND1 terminal, REFGND1 terminal, and REFGND2 terminal of the ADC chip are all connected to ground.

[0053] The ADC chip is an integrated circuit that converts analog signals into digital signals. Its AVCC pin receives a 5V operating voltage to ensure conversion accuracy. The AGND pin is the analog ground pin, connected to the system ground plane through multiple grounding points to effectively suppress common-mode interference. The REFCAPB and REFCAP2 pins are reference voltage decoupling pins, forming a low-impedance loop through the fifth and sixth capacitors in parallel, which can absorb high-frequency noise. The REFIN / REFOUT pins serve as reference voltage input and output terminals, using the seventh capacitor for bypass filtering to stabilize the reference voltage. The REGCAP1 pin is the internal regulator decoupling pin, filtering out power supply ripple through the eighth capacitor.

[0054] Specifically, the AVCC terminal of the ADC chip is connected to a regulated 5V power supply, and the AGND terminal is directly connected to the system analog ground plane to form a stable potential reference. A fifth capacitor is connected between the REFCAPB and AGND1 terminals to eliminate high-frequency noise from the reference voltage circuit; a sixth capacitor is placed between the REFCAP2 and AGND1 terminals to suppress transient fluctuations in the reference voltage. The seventh capacitor configured at the REFIN / REFOUT terminals forms a π-type filter network for the reference voltage, reducing the impact of external interference on conversion accuracy. The eighth capacitor connected to the REGCAP1 terminal acts as an energy storage element, smoothing voltage fluctuations at the output of the internal regulator. All capacitors are surface-mount ceramic capacitors arranged in parallel to form a distributed filtering structure. This scheme sets dedicated filter capacitors at the reference voltage terminal, regulator terminal, and power supply terminal of the ADC chip to form a multi-stage noise suppression network. Through the collaborative filtering design of the REFCAPB and REFCAP2 terminals, quantization noise is significantly reduced. The distributed capacitor layout eliminates the propagation path of high-frequency interference in PCB traces, and the multi-point grounding design reduces the common-mode error introduced by ground loops, thereby improving the signal conversion accuracy and anti-interference capability of the multi-channel acquisition system.

[0055] Preferably, the conversion circuit 4 further includes a fifth capacitor, a sixth capacitor, a seventh capacitor, and an eighth capacitor; the REFCAPB terminal of the ADC chip and the REFCAPB terminal of the ADC chip are both connected to the AGND1 terminal of the ADC chip through the fifth capacitor; the REFCAP2 terminal of the ADC chip is connected to the AGND1 terminal of the ADC chip through the sixth capacitor; the REFIN / REFOUT terminal of the ADC chip is connected to the AGND1 terminal of the ADC chip through the seventh capacitor; the REFCAP1 terminal of the ADC chip is connected to the AGND1 terminal of the ADC chip through the eighth capacitor; the fifth, sixth, seventh, and eighth capacitors are used for filtering and decoupling of the power supply and reference voltage.

[0056] The ADC chip is an integrated circuit that converts analog signals into digital signals. It can be implemented using an analog-to-digital converter chip with multi-channel input capability. Its AVCC terminal is the analog power input terminal, AGND terminal is the analog ground pin, and REFGND terminal is the reference voltage ground pin. The fifth capacitor is a filter element connected between the REFCAPB and AGND1 terminals of the ADC chip, used to suppress high-frequency noise on the reference voltage pin. The sixth capacitor is a decoupling element connected between the REFCAP2 and AGND1 terminals of the ADC chip, specifically implemented using a surface-mount capacitor with low equivalent series resistance, used to eliminate instantaneous voltage fluctuations in the power supply line. The seventh capacitor is an energy storage element connected between the REFIN / REFOUT terminals of the ADC chip and AGND1 terminal, specifically implemented using a tantalum capacitor or polymer capacitor, used to stabilize the level of the reference voltage output terminal. The eighth capacitor is a voltage regulator element connected between the REGCAP1 and AGND1 terminals of the ADC chip, specifically implemented using a multilayer ceramic capacitor, used to reduce ripple interference from the internal voltage regulation circuit.

[0057] Specifically, after the AVCC terminal of the ADC chip is connected to a 5V power supply, its internal analog circuit begins to operate. The input analog signal is transmitted to the input terminal of the ADC chip through a multi-stage conditioning circuit. The fifth capacitor is connected between the REFCAPB terminal and the AGND1 terminal of the ADC chip to filter out high-frequency noise in the reference voltage loop; the sixth capacitor is connected between the REFCAP2 terminal and the AGND1 terminal to absorb transient current changes on the power supply line; the seventh capacitor is connected in parallel between the REFIN / REFOUT terminal and the AGND1 terminal to maintain the stability of the reference voltage through charging and discharging; the eighth capacitor is placed between the REFCAP1 terminal and the AGND1 terminal to suppress low-frequency ripple generated by the internal voltage regulator module. The four sets of capacitors filter and decouple different nodes of the power supply, reference voltage, and internal circuitry, forming a multi-stage noise suppression structure.

[0058] In some specific implementations, the capacitance of the fifth capacitor can be selected as 10μF, the capacitance of the sixth capacitor can be 10μF, the capacitance of the seventh capacitor can be 10μF, and the capacitance of the eighth capacitor can be 10μF. The withstand voltage of the above capacitors must be higher than the operating voltage of the corresponding node. The AGND1 terminal of the ADC chip is connected to the system analog ground plane through an independent trace to reduce the influence of ground impedance on the signal. This solution achieves partitioned processing of power supply noise, reference voltage fluctuations, and internal circuit ripple by setting dedicated filter capacitors at the REFCAPB, REFCAP2, REFIN / REFOUT, and REGCAP1 terminals of the ADC chip, which significantly improves the stability of signal conversion. This application can reduce power supply interference and reference voltage drift during analog-to-digital conversion, improve signal acquisition accuracy, and simplify circuit layout complexity through multi-node collaborative filtering design, thereby enhancing the long-term operational reliability of the system in industrial electromagnetic interference environments.

[0059] Preferably, the controller 6 is a programmable gate array chip.

[0060] Programmable gate array (PGA) chips are integrated circuits that can be programmed to perform customized digital logic functions. They contain configurable logic units, memory modules, and input / output units. This chip generates control logic through a hardware description language, directly driving the control signals of analog signal type selection circuit 1 and analog signal channel selection circuit 3, while simultaneously processing signal data from isolation circuit 5. In this solution, this feature enables parallel processing of multi-channel switching control, signal acquisition timing synchronization, and display interaction logic, thereby avoiding the latency issues caused by the sequential execution of traditional microcontrollers.

[0061] Specifically, the programmable gate array (PGA) chip generates multiple independent control signals through a preset logic configuration, which are sent to isolation circuit 5 to drive the optocoupler relay in analog signal type selection circuit 1 and the data selector in analog signal channel selection circuit 3. For example, when a signal type needs to be switched, the chip sends a pulse signal to the optocoupler relay through isolation circuit 5, triggering the path switching between the input terminal and the instrumentation amplifier. Simultaneously, the chip dynamically adjusts the channel address signal of the data selector according to the user command received by display 7, realizing the polling acquisition of multiple analog signals. During the acquisition process, the chip synchronously controls the ADC chip of conversion circuit 4 to complete the analog-to-digital conversion, caches the conversion result in internal memory, and finally outputs it to display 7 through the display interface.

[0062] Other structures of the multi-channel acquisition device described in this embodiment are described in the prior art.

[0063] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the technical solution of the present utility model shall still fall within the scope of the technical solution of the present utility model.

Claims

1. A multi-channel data acquisition device, characterized in that, include: Analog signal type selection circuit, signal conditioning circuit, analog signal channel selection circuit, conversion circuit, isolation circuit, controller and display; The output of the analog signal type selection circuit is connected to the input of the signal conditioning circuit. The output of the signal conditioning circuit is connected to the input of the analog channel selection circuit; The output of the analog channel selection circuit is connected to the input of the isolation circuit through the conversion circuit; The output of the isolation circuit is connected to the controller; The controller is connected to the control terminal of the analog quantity type selection circuit and the control terminal of the analog quantity channel selection circuit through the isolation circuit to achieve electrical isolation; The controller is connected to the display and is used to perform analog signal type selection and analog signal channel selection control on the display.

2. The multi-channel acquisition device according to claim 1, characterized in that, The analog quantity type selection circuit includes an input terminal, a bidirectional trigger diode, a first capacitor, a first resistor, an optocoupler relay, a first diode, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a second diode, a third diode, a fourth diode, a fifth diode, and an instrumentation amplifier; The input terminals include a first port and a second port. The first port is connected to one end of the bidirectional trigger diode and one end of the first capacitor, and the second port is connected to the other end of the bidirectional trigger diode and the other end of the first capacitor. The third pin of the optocoupler relay is connected to one end of the first capacitor, the fourth pin of the optocoupler relay is connected to the other end of the first capacitor through the first resistor, the second pin of the optocoupler relay is connected to the positive terminal of the first diode and one end of the second resistor respectively, and the first pin of the optocoupler is connected to the negative terminal of the first diode and the other end of the second resistor respectively. One end of the third resistor is connected to the first pin of the optocoupler, and the other end of the third resistor is connected to the AC / DC converter; The non-inverting input terminal of the instrumentation amplifier is connected to the third pin of the optocoupler relay through the fourth resistor; the inverting input terminal of the instrumentation amplifier is connected to the other end of the first capacitor through the fifth resistor; the first gain setting terminal of the instrumentation amplifier is connected to the second gain setting terminal of the instrumentation amplifier through the fifth resistor; the positive power supply terminal of the instrumentation amplifier is connected to a positive 12V power supply; the negative power supply terminal of the instrumentation amplifier is connected to a negative 12V power supply; the reference terminal of the instrumentation amplifier is connected to ground; and the output terminal of the instrumentation amplifier is connected to the signal conditioning circuit. The positive terminal of the second diode is connected to a negative 12V power supply, and the negative terminal of the second diode is connected to the non-inverting input terminal of the instrumentation amplifier. The negative terminal of the third diode is connected to a positive 12V power supply, and the positive terminal of the third diode is connected to the non-inverting input terminal of the instrumentation amplifier. The negative terminal of the fourth diode is connected to a positive 12V power supply, and the positive terminal of the fourth diode is connected to the inverting input terminal of the instrumentation amplifier. The positive terminal of the fifth diode is connected to a negative 12V power supply, and the negative terminal of the fifth diode is connected to the inverting input terminal of the instrumentation amplifier.

3. The multi-channel acquisition device according to claim 1, characterized in that, The signal conditioning circuit includes a first operational amplifier circuit and a second operational amplifier circuit; The input terminal of the first operational amplifier circuit is connected to the output terminal of the analog quantity type selection circuit; The input terminal of the second operational amplifier circuit is connected to the output terminal of the first operational amplifier circuit, and the output terminal of the second operational amplifier circuit is connected to the input terminal of the analog channel selection circuit.

4. The multi-channel acquisition device according to claim 1, characterized in that, The first operational amplifier circuit includes a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a first operational amplifier, a second capacitor, and a third capacitor; One end of the sixth resistor is connected to the output terminal of the instrumentation amplifier, and the other end of the sixth resistor is connected to the output terminal of the first operational amplifier through the second capacitor; One end of the seventh resistor is connected to the other end of the sixth resistor, and the other end of the seventh resistor is connected to the non-inverting input terminal of the first operational amplifier; One end of the third capacitor is connected to the non-inverting input terminal of the first operational amplifier, and the other end of the third capacitor is connected to ground; One end of the eighth resistor is connected to ground, and the other end of the eighth resistor is connected to the inverting input terminal of the first operational amplifier; The output terminal of the first operational amplifier is connected to the inverting input terminal of the first operational amplifier through the ninth resistor. The positive power supply terminal of the first operational amplifier is connected to a positive 12V power supply, and the negative power supply terminal of the first operational amplifier is connected to a negative 12V power supply.

5. A multi-channel acquisition device according to claim 3, characterized in that, The second operational amplifier circuit includes a tenth resistor, an eleventh resistor, a twelfth resistor, and a second operational amplifier; The non-inverting input of the second operational amplifier is connected to the first operational amplifier circuit through the tenth resistor; One end of the eleventh resistor is connected to ground, and the other end of the eleventh resistor is connected to the inverting input terminal of the second operational amplifier; The output terminal of the second operational amplifier is connected to the inverting input terminal of the second operational amplifier through the twelfth resistor. The positive power supply terminal of the second operational amplifier is connected to a positive 12V power supply, and the negative power supply terminal of the second operational amplifier is connected to a negative 12V power supply. The output of the second operational amplifier is connected to the analog signal type selection circuit.

6. The multi-channel acquisition device according to claim 1, characterized in that, The analog channel selection circuit includes a data selector, a fourth capacitor, a thirteenth resistor, a fourteenth resistor, a first optocoupler, a fifteenth resistor, a sixteenth resistor, a second optocoupler, a seventeenth resistor, an eighteenth resistor, and a third optocoupler; The VDD terminal of the data selector is connected to the VSS terminal of the data selector through a fourth capacitor. The VDD terminal, VEE terminal, and INH terminal of the data selector are all connected to ground. The VSS terminal of the data selector is connected to 5V. The COM OUT / IN terminal of the data selector is connected to the conversion circuit. The EN terminal of the first optocoupler is connected to the A terminal of the data selector and the output terminal of the first optocoupler through the thirteenth resistor. The C terminal of the first optocoupler is connected to the controller through the fourteenth resistor. The GND terminal of the first optocoupler is connected to ground. The A terminal of the first optocoupler is connected to a 3.3V power supply. The EN terminal and VCC terminal of the first optocoupler are both connected to a 5V power supply. The EN terminal of the second optocoupler is connected to the B terminal of the data selector and the output terminal of the second optocoupler through the fifteenth resistor. The C terminal of the second optocoupler is connected to the controller through the sixteenth resistor. The GND terminal of the second optocoupler is connected to ground. The A terminal of the second optocoupler is connected to a 3.3V power supply. The EN terminal and the VCC terminal of the second optocoupler are both connected to a 5V power supply. The EN terminal of the third optocoupler is connected to the C terminal of the data selector and the output terminal of the third optocoupler through the seventeenth resistor. The C terminal of the third optocoupler is connected to the controller through the eighteenth resistor. The GND terminal of the third optocoupler is connected to ground. The A terminal of the third optocoupler is connected to a 3.3V power supply. The EN terminal and VCC terminal of the third optocoupler are both connected to a 5V power supply.

7. A multi-channel acquisition device according to claim 6, characterized in that, The first optocoupler, the second optocoupler, and the third optocoupler are used to achieve electrical isolation between the input signal and the analog channel selection circuit.

8. A multi-channel acquisition device according to claim 1, characterized in that, The conversion circuit includes an ADC chip; The AVCC terminal of the ADC chip is connected to a 5V power supply. The AGND terminal, AGND1 terminal, REFGND1 terminal, and REFGND2 terminal of the ADC chip are all connected to ground.

9. A multi-channel acquisition device according to claim 8, characterized in that, The conversion circuit also includes a fifth capacitor, a sixth capacitor, a seventh capacitor, and an eighth capacitor; The REFCAPB terminal of the ADC chip and the REFCAPB terminal of the ADC chip are both connected to the AGND1 terminal of the ADC chip through the fifth capacitor. The REFCAP2 terminal of the ADC chip is connected to the AGND1 terminal of the ADC chip through the sixth capacitor; The REFIN / REFOUT terminals of the ADC chip are connected to the AGND1 terminal of the ADC chip through the seventh capacitor; The REGCAP1 terminal of the ADC chip is connected to the AGND1 terminal of the ADC chip through the eighth capacitor; The fifth, sixth, seventh, and eighth capacitors are used for filtering and decoupling of the power supply and reference voltage.

10. A multi-channel acquisition device according to claim 1, characterized in that, The controller uses a programmable gate array (PGA) chip.

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