Multi-type analog input acquisition circuit and device

Abstract

The invention relates to the technical field of signal acquisition, in particular to a multi-type analog quantity input acquisition circuit and device.The multi-type analog quantity input acquisition circuit comprises a processing module and an acquisition module used for achieving voltage acquisition, current acquisition and resistance acquisition, the acquisition module comprises a sampling resistor, and the sampling resistor is used for being connected with the output end of a sensor to be tested; the processing module is used for acquiring the voltage at the two ends of the sampling resistor to obtain the output signal of the to-be-detected sensor, and is also used for directly determining the output voltage of the to-be-detected sensor according to the voltage at the two ends of the sampling resistor when the to-be-detected sensor outputs the voltage; the sampling resistor is used for determining the output current of the to-be-tested sensor according to the voltage at two ends of the sampling resistor and the resistance value of the sampling resistor when the to-be-tested sensor outputs the current. No matter a current signal, a voltage signal or a resistance signal output by the sensor, the output signal of the sensor can be acquired and converted and transmitted to an external port, and the sensor can adapt to various use scenes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of signal acquisition, in particular to a multi-type analog quantity input acquisition circuit and device. BACKGROUND

[0002] With the continuous development of the Internet of Things, sensors for collecting various environmental data are widely used in the prior art. There are many types of existing sensors, and different sensors output different types of signals. Different interfaces need to be used for information acquisition according to different signal types. In the existing use scenario, when monitoring a device or a place, multiple different sensors need to be used to collect multiple different data. However, because different types of sensors output different types of signals, in order to collect the output signals of these sensors, multiple acquisition circuits need to be configured on site to collect different types of sensor output signals and transmit them to the corresponding interface. For example, when monitoring the working state of a diesel generator or an emergency power supply vehicle protection and control device (unit controller), sensors need to be used to collect oil level, oil pressure, water temperature and other analog quantities. The signal types output by these sensors include current signals, voltage signals and resistance signals. Three types of acquisition circuits need to be configured for these output signals, which increases the workload during circuit installation. If the acquisition circuit or interface is incorrectly connected, it may cause damage to the corresponding device or even burn out the circuit.

[0003] In order to solve this technical problem, the acquisition circuit is improved in the prior art, and the voltage signals and current signals output by the sensors are uniformly converted into the same type of signal output, so that one type of acquisition circuit can be used to collect all sensor output signals. For example, a self-detecting signal acquisition circuit based on analog quantity current-voltage mixed input is disclosed in Chinese patent application file with publication number CN119595982A. The circuit controls the switch selection circuit to switch gears through the output voltage size between the differential mode resistors in the follower circuit, so that the signal acquisition circuit switches between receiving voltage signals or current signals to achieve the collection of different types of signals. However, this circuit switches between voltage signals and current signals through gear shifting. This gear shifting method can only be used when the sensor output signal is a voltage signal or a current signal, and cannot convert resistance signals, so the use scenario is limited. SUMMARY

[0004] The purpose of the present application is to provide a multi-type analog quantity input acquisition circuit and device to solve the problem that the existing acquisition circuit that can switch acquisition signals cannot collect resistance signals output by sensors.

[0005] The application provides a multi-type analog input acquisition circuit to solve the above technical problems, comprising a processing module and an acquisition module for realizing voltage acquisition, current acquisition and resistance acquisition, the acquisition module comprises a sampling resistor, the sampling resistor is used to be connected with an output end of a sensor to be measured to acquire an output signal of the sensor to be measured, the processing module is used to acquire a voltage across the sampling resistor to obtain the output signal of the sensor to be measured, the sampling resistor is further connected with a constant current source, the constant current source is used to provide a current when the sensor to be measured outputs resistance, and the processing module obtains the output resistance of the sensor to be measured according to the acquired voltage across the sampling resistor, the resistance of the sampling resistor and the current of the constant current source; the processing module is further used to directly determine the output voltage of the sensor to be measured according to the voltage across the sampling resistor when the sensor to be measured outputs voltage, and is used to determine the output current of the sensor to be measured according to the voltage across the sampling resistor and the resistance of the sampling resistor when the sensor to be measured outputs current.

[0006] Further, the sampling resistor comprises a first sampling resistor and a second sampling resistor, the first sampling resistor and the second sampling resistor are connected in parallel and used to be connected with the output end of the sensor to be measured, a second control switch is arranged on a loop in which the second sampling resistor is located, the second control switch is used to be closed when the sensor to be measured outputs a current signal, so that the first sampling resistor and the second sampling resistor are connected in parallel and connected with the sensor to be measured, and is used to be opened when the sensor to be measured outputs voltage or resistance, so that only the first sampling resistor is connected with the output end of the sensor to be measured.

[0007] Further, the constant current source is connected to the loop in which the sampling resistor is located through a first control switch, and is used to be closed when the sensor to be measured outputs resistance, so as to provide constant current for the loop in which the sampling resistor is located.

[0008] Further, the first control switch and the second control switch are both connected with the processing module, and the processing module is used to control the first control switch and the second control switch according to the type of the output signal of the sensor to be measured.

[0009] Further, an output end of the processing module is connected with an external interface, so as to acquire the type of the output signal of the sensor to be measured through the external interface.

[0010] Further, the processing module is further connected with a man-machine interface, and is used to acquire the type of the external interface through the man-machine interface and determine the type of the output signal of the sensor according to the type of the external interface.

[0011] Further, the processing module is connected with the sampling resistor through a voltage follower circuit, and is used to realize isolation between the voltage signal acquired by the sampling resistor and the processing module.

[0012] Further, the first control switch and the second control switch are transistors or relays.

[0013] Furthermore, the constant current source includes a controllable switch and an operational amplifier circuit. One input terminal of the operational amplifier circuit is connected to the power supply VCC, and the other input terminal is connected to the output terminal of the operational amplifier. The controllable switch is connected in series between the power supply VCC and the acquisition module. The control terminal of the controllable switch is connected to the output terminal of the operational amplifier circuit so that it can be turned on when a signal is received from the output terminal of the operational amplifier circuit, so that the power supply VCC provides a stable current to the acquisition module.

[0014] A multi-type analog input acquisition device includes a housing and a circuit board. The circuit board is equipped with multi-type analog input acquisition circuits, each including a processing module and acquisition modules for voltage, current, and resistance acquisition. Each acquisition module includes a sampling resistor connected to the output terminal of a sensor under test (SUT) to acquire its output signal. The processing module obtains the voltage across the sampling resistor to determine the SUT's output signal. The sampling resistor is also connected to a constant current source, which provides current when the SUT outputs resistance. The processing module determines the SUT's output resistance based on the acquired voltage across the sampling resistor, the resistor's resistance, and the constant current source's current. Furthermore, the processing module determines the SUT's output voltage directly from the sampling resistor when the SUT outputs voltage, and determines the SUT's output current based on the voltage across the sampling resistor and its resistance when the SUT outputs current.

[0015] Furthermore, the sampling resistor includes a first sampling resistor and a second sampling resistor. The first sampling resistor and the second sampling resistor are connected in parallel and used to connect to the output terminal of the sensor under test. A second control switch is provided on the circuit where the second sampling resistor is located. The second control switch is used to close when the sensor under test outputs a current signal, so that the first sampling resistor and the second sampling resistor are connected in parallel to the sensor under test. It is also used to open when the sensor under test outputs voltage or resistance, so that only the first sampling resistor is connected to the output terminal of the sensor under test.

[0016] Furthermore, the constant current source is connected to the circuit containing the sampling resistor via a first control switch, which is used to close when the sensor under test outputs resistance, thereby providing a constant current to the circuit containing the sampling resistor.

[0017] Furthermore, both the first control switch and the second control switch are connected to the processing module, which controls the first control switch and the second control switch according to the type of output signal from the sensor under test.

[0018] Furthermore, the output of the processing module is connected to an external interface to obtain the type of output signal from the sensor under test through the external interface.

[0019] Furthermore, the processing module is also connected to a human-machine interface, which is used to obtain the type of external interface through the human-machine interface and determine the type of sensor output signal based on the type of external interface.

[0020] Furthermore, the processing module is connected to the sampling resistor via a voltage follower circuit to isolate the voltage signal acquired by the sampling resistor from the processing module.

[0021] Furthermore, the first control switch and the second control switch are transistors or relays.

[0022] Furthermore, the constant current source includes a controllable switch and an operational amplifier circuit. One input terminal of the operational amplifier circuit is connected to the power supply VCC, and the other input terminal is connected to the output terminal of the operational amplifier. The controllable switch is connected in series between the power supply VCC and the acquisition module. The control terminal of the controllable switch is connected to the output terminal of the operational amplifier circuit so that it can be turned on when a signal is received from the output terminal of the operational amplifier circuit, so that the power supply VCC provides a stable current to the acquisition module.

[0023] The beneficial effects of this invention are as follows: As an improved invention, the acquisition module of this invention is equipped with a sampling resistor for acquiring the sensor output signal. When acquiring the resistance signal output by the sensor, the sampling resistor is connected to a constant current source. The processing module can calculate the magnitude of the resistance signal output by the sensor based on the voltage across the sampling resistor, the resistance value of the sampling resistor, and the current of the constant current source, thereby realizing the acquisition of the resistance signal output by the sensor. At the same time, the processor can also directly determine the output voltage of the sensor under test based on the voltage across the sampling resistor when the sensor under test outputs voltage, and determine the output current of the sensor under test based on the voltage across the sampling resistor and the resistance value of the sampling resistor when the sensor under test outputs current. Therefore, regardless of whether the sensor outputs a current signal, voltage signal, or resistance signal, this invention can acquire and convert the sensor output signal and transmit it to an external port, adapting to various application scenarios. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a multi-type analog input acquisition circuit. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0026] This invention sets up a sampling resistor to collect the output signal of the sensor. When collecting the resistance signal output by the sensor, the sampling resistor is connected to a constant current source. The processing module can calculate the magnitude of the resistance signal output by the sensor based on the voltage across the sampling resistor, the resistance value of the sampling resistor, and the current of the constant current source.

[0027] Implementation methods of multi-type analog input acquisition circuits In the prior art, the types of output signals of sensors include voltage signals, current signals and resistance signals (that is, the physical quantity currently detected by the sensor can be reflected by the resistance value of the sensor itself; for example, a thermistor is used as a sensor to measure the ambient temperature, and the current temperature can be determined by measuring the resistance value of the thermistor). Therefore, the acquisition circuit of the present invention can adapt to a variety of sensor types.

[0028] like Figure 1 As shown, this invention proposes a multi-type analog input acquisition circuit, positioned between a sensor and an external interface, used to convert various types of output signals from the sensor into a unified signal and transmit this signal to the external interface. The input terminal of this acquisition circuit is connected to the output terminal of the sensor to be acquired, and the output terminal of the acquisition circuit is connected to the external interface. The circuit includes a processing module and an acquisition module. The acquisition module is mainly used to acquire various types of output signals from the sensor under test. To achieve this, a sampling resistor is included in the sampling module, which is connected to the output terminal of the sensor under test. The processing module is mainly used to acquire the voltage across the sampling resistor and, based on this voltage signal and the type of sensor output signal, select the corresponding method to calculate the signal output by the sensor under test. Simultaneously, the processing module is also used to control the acquisition module to switch the corresponding acquisition mode according to the type of sensor output signal.

[0029] In the data acquisition module, such as Figure 1 As shown, the sampling resistor includes a first sampling resistor. R 2. Second sampling resistor R 1. A constant current source, which is connected to a first sampling resistor via a first control switch (i.e., control switch 1 in the figure). R 2. Connection, first sampling resistor R 2 and second sampling resistor R 1. Parallel connection, with the first sampling resistor R A second control switch (i.e., control switch 2 in the figure) is provided in the circuit of 2. Both the first and second control switches are controlled by the processing module. As an example, the first and second control switches can be transistors or relays.

[0030] To further improve the accuracy of the acquisition results, in the first sampling resistor R A filter capacitor is connected in parallel on the 2nd. C 1, and at the first sampling resistor R A voltage follower U2A is installed between the sensor and the processing module to isolate the sensor from the processing module. This prevents the voltage across the sampling resistor from being pulled down by the high-impedance load (i.e., the processing module) in the circuit. The positive feedback input of the voltage follower is connected to a current-limiting resistor. R 4. With the acquisition resistor ROne end of 2 is connected, and the output of the voltage follower is connected through a current-limiting resistor. R 6. Connect to the analog-to-digital converter module. Resistor R2 is a real resistor on the board. Due to the requirement that the op-amp input cannot be left floating, when the external input terminal is floating, the op-amp input terminal is also floating, and the voltage at the input terminal has no definite reference point. This will lead to instability in the op-amp's operating point and unpredictable output. In addition, the op-amp's input resistance is very high. If the input terminal is floating, surrounding electromagnetic interference and electrostatic charges will also cause the input terminal voltage to drift, thus affecting the op-amp's operation. Grounding resistor R2 ensures that the voltage is 0 when no external input is connected, which is logically correct. When no sensor is connected (i.e., the external input is floating), the first sampling resistor... R 2. A bias current loop is provided for the operational amplifier that forms the voltage follower. When the sensor's output signal is a voltage signal, the acquisition module switches to voltage acquisition mode, and the processing module controls the first and second control switches to open. Only the first sampling resistor R2 is connected to the sensor output port. Therefore, the voltage value across the first sampling resistor R2 at this time is the voltage signal value output by the sensor. Ux 2 represents the voltage signal value output by the sensor.

[0031] When the sensor output signal is a current signal, the acquisition module switches to current acquisition mode, and the processing module controls the first control switch to open and the second control switch to close, thus activating the second sampling resistor. R 1 and the first sampling resistor R 2 in parallel, at this time, the first sampling resistor R 2 and second sampling resistor R When connected in parallel, the current output by the sensor flows into the parallel resistors R1 and R2 at the sensor output port. The processor then samples the first sampling resistor. R The voltage across 2 is the first sampling resistor. R 2 and second sampling resistor R 1 parallel voltage Ux 3, and according to I x = Ux 3 / ( R1 ∥ R 2) It can calculate the current information output by the sensor, where I x This is the current signal output by the sensor.

[0032] If only the first sampling resistor is used R 2. Measuring the current signal may be affected by the first sampling resistor. R If the voltage is too high (e.g., R2), the measured voltage may exceed the measurement range, potentially burning out the acquisition circuit if no protection device is available. Therefore, multiple resistors can be connected in parallel; for example, it is necessary to connect a resistor R1, which is smaller than R2, in parallel with R2.

[0033] To obtain an accurate current signal from the sensor, the first sampling resistor needs to be... R The resistance value of the first sampling resistor is limited by 2. R The resistance value of 2 should not be too large, if the first sampling resistor R 2. An excessively large current will cause a significant voltage drop in the operational amplifier's bias current, affecting the operational amplifier's input. Simultaneously, the first sampling resistor... R 2 should not be too small either, if the first sampling resistor R 2. If the current is too small, it will cause current shunting during current acquisition, resulting in the voltage signal acquired by the processing module being too small, without a suitable range, and causing errors.

[0034] When the sensor output signal is a resistance signal, the acquisition module switches to resistance acquisition mode, and the processing module controls the first control switch to close and the second control switch to open, so that the constant current source is connected to the first sampling resistor. R 2. Connection, at this time the first sampling resistor R 2. Set at the sensor output port. If the sensor output resistance is... Rx Then the resistor Rx A parallel circuit is formed with the first sampling resistor R2, and the constant current source is the first sampling resistor R2 and the resistor connected in parallel. Rx Provide constant current I m The voltage signal across the first sampling resistor R2 Ux 1 (that is, the voltage across the parallel circuit of the sensor and the first sampling resistor R2) is processed by the analog-to-digital converter module and then transmitted to the processing module. The processing module then... Ux =( Rx ∥ R 2)×I m The sensor resistance signal value can be calculated. Rx Size.

[0035] The constant current source can be an existing constant current source, or a common power supply can be selected and a matching circuit designed to form a constant current source. As one embodiment, this invention proposes a constant current source including a controllable switch and an operational amplifier circuit. The positive feedback terminal of the operational amplifier circuit is connected to the power supply VCC through a first voltage divider resistor R5, which is grounded through a second voltage divider resistor R8. The negative feedback terminal of the operational amplifier circuit is connected to the output terminal of the operational amplifier through a capacitor C1, so that a signal is sent through the output terminal when the output voltage of the power supply VCC is equal to the previous output voltage. The controllable switch is connected in series with the power supply VCC and the first controllable switch. The control terminal of the controllable switch is connected to the output terminal of the operational amplifier circuit through a current-limiting resistor R7, so that it conducts when it receives a signal sent from the output terminal of the operational amplifier circuit, allowing the power supply VCC to supply power to the sampling resistor. The output current of this constant current source is I. m =( VCC_REF - VCC_REF× R 8 / ( R 5+ R 8)) / R 3.

[0036] When the sensor outputs a signal, the processing module selects the corresponding processing method based on the type of signal transmitted by the sensor. When acquiring the type of the sensor output signal, since the processing module cannot directly read the type of the external interface, it needs to read the type of the external interface through the human-machine interface and then send the type to the processing module. Because the type of the sensor output signal must correspond to the type of the signal received by the external interface during connection, the type of the sensor output signal can be obtained based on the type of the external interface. After determining the type, the processing module controls the first and second control switches to open or close to switch modes, processing the voltage across the sampling resistor according to the corresponding model. Since the data processed by the processing module is digital, while the voltage across the sampling resistor is analog, it needs to be converted from analog to digital first. If the processing module integrates an analog-to-digital converter, it can directly process the voltage data. If the processing module cannot perform analog-to-digital conversion, an ADC module needs to be added before the processing module.

[0037] Implementation methods for multi-type analog input acquisition devices This invention proposes a multi-type analog input acquisition device, including a housing and a circuit board. The circuit board is positioned between the sensor and an external interface to convert various types of output signals from the sensor into a unified signal and transmit this signal to the external interface. The input terminal of the acquisition circuit is connected to the output terminal of the sensor to be acquired, and the output terminal of the acquisition circuit is connected to the external interface. The circuit includes a processing module and an acquisition module. The acquisition module is mainly used to acquire various types of output signals from the sensor under test. To achieve this, a sampling resistor is included in the sampling module and connected to the output terminal of the sensor under test. The processing module is mainly used to acquire the voltage across the sampling resistor and, based on this voltage signal and the type of sensor output signal, select the appropriate method to calculate the signal output by the sensor under test. Simultaneously, the processing module is also used to control the acquisition module to switch the corresponding acquisition mode according to the type of sensor output signal.

[0038] In the data acquisition module, such as Figure 1 As shown, the sampling resistor includes a first sampling resistor. R 2. Second sampling resistor R 1. A constant current source, which is connected to a first sampling resistor via a first control switch (i.e., control switch 1 in the figure). R 2. Connection, first sampling resistor R 2 and second sampling resistor R 1. Parallel connection, with the first sampling resistor RA second control switch (i.e., control switch 2 in the figure) is provided in the circuit of 2. Both the first and second control switches are controlled by the processing module. As an example, the first and second control switches can be optocouplers or relays.

[0039] To further improve the accuracy of the acquisition results, in the first sampling resistor R A filter capacitor is connected in parallel on the 2nd. C 1, and at the first sampling resistor R A voltage follower U2A is installed between the sensor and the processing module to isolate the sensor from the processing module. This prevents the voltage across the sampling resistor from being pulled down by the high-impedance load (i.e., the processing module) in the circuit. The positive feedback input of the voltage follower is connected to a current-limiting resistor. R 4. With the acquisition resistor R One end of 2 is connected, and the output of the voltage follower is connected through a current-limiting resistor. R 6. Connected to the analog-to-digital converter module. When no sensor is connected (i.e., the external input is floating), the first sampling resistor... R 2. Provides a bias current loop for the operational amplifier that forms a voltage follower.

[0040] When the sensor's output signal is a voltage signal, the acquisition module switches to voltage acquisition mode. The processing module controls the first and second control switches to open, leaving only the first sampling resistor R2 connected to the sensor's output port. Therefore, the voltage value across the first sampling resistor R2 at this time is the voltage signal value output by the sensor. Ux 2 represents the voltage signal value output by the sensor.

[0041] When the sensor output signal is a current signal, the acquisition module switches to current acquisition mode, and the processing module controls the first control switch to open and the second control switch to close, thus activating the second sampling resistor. R 1 and the first sampling resistor R 2 in parallel, at this time, the first sampling resistor R 2 and second sampling resistor R When connected in parallel, the current output by the sensor flows into the parallel resistors R1 and R2 at the sensor output port. The processor then samples the first sampling resistor. R The voltage across 2 is the first sampling resistor. R 2 and second sampling resistor R 1 parallel voltage Ux 3, and according to I x = Ux 3 / ( R1 ∥ R 2) It can calculate the current information output by the sensor, where I x This is the current signal output by the sensor.

[0042] To avoid current shunting when measuring the sensor current signal, the first sampling resistor R The resistance value of resistor 2 should not be set too small. If only the first sampling resistor is used... R 2. Measuring the current signal may be affected by the first sampling resistor. R If the voltage is too large, the measured voltage will be too high and exceed the measurement range. If there is no protection device, the acquisition circuit may be burned out. Therefore, multiple resistors can be connected in parallel. For example, a smaller resistor R1 can be connected in parallel with R2 to increase the measured voltage and ensure the safety and reliability of the acquisition circuit.

[0043] To obtain an accurate current signal from the sensor, the first sampling resistor needs to be... R The resistance value of the first sampling resistor is limited by 2. R The resistance value of 2 should not be too large, if the first sampling resistor R 2. An excessively large current will cause a significant voltage drop in the operational amplifier's bias current, affecting the operational amplifier's input. Simultaneously, the first sampling resistor... R 2 should not be too small either, if the first sampling resistor R 2. If the current is too small, it will cause current shunting during current acquisition, resulting in the voltage signal acquired by the processing module being too small, without a suitable range, and causing errors.

[0044] When the sensor output signal is a resistance signal, the acquisition module switches to resistance acquisition mode, and the processing module controls the first control switch to close and the second control switch to open, so that the constant current source is connected to the first sampling resistor. R 2. Connection, at this time the first sampling resistor R 2. Set at the sensor output port. If the sensor output resistance is... Rx Then the resistor Rx A parallel circuit is formed with the first sampling resistor R2, and the constant current source is the first sampling resistor R2 and the resistor connected in parallel. Rx Provide constant current I m The voltage signal across the first sampling resistor R2 Ux 1 (that is, the voltage across the parallel circuit of the sensor and the first sampling resistor R2) is processed by the analog-to-digital converter module and then transmitted to the processing module. The processing module then... Ux =( Rx ∥ R 2)×I m The sensor resistance signal value can be calculated. Rx Size.

[0045] The constant current source can be an existing constant current source, or a common power supply can be selected and a matching circuit designed to form a constant current source. As one embodiment, this invention proposes a constant current source including a controllable switch and an operational amplifier circuit. The positive feedback terminal of the operational amplifier circuit is connected to the power supply VCC through a first voltage divider resistor R5, which is grounded through a second voltage divider resistor R8. The negative feedback terminal of the operational amplifier circuit is connected to the output terminal of the operational amplifier through a capacitor C1, so that a signal is sent through the output terminal when the output voltage of the power supply VCC is equal to the previous output voltage. The controllable switch is connected in series with the power supply VCC and the first controllable switch. The control terminal of the controllable switch is connected to the output terminal of the operational amplifier circuit through a current-limiting resistor R7, so that it conducts when it receives a signal sent from the output terminal of the operational amplifier circuit, allowing the power supply VCC to supply power to the sampling resistor. The output current of this constant current source is I. m =( VCC_REF - VCC_REF × R 8 / ( R 5+ R 8)) / R 3.

[0046] When the sensor outputs a signal, the processing module selects the corresponding processing method based on the type of signal transmitted by the sensor. When acquiring the type of the sensor output signal, since the processing module cannot directly read the type of the external interface, it needs to read the type of the external interface through the human-machine interface and then send the type to the processing module. Because the type of the sensor output signal must correspond to the type of the signal received by the external interface during connection, the type of the sensor output signal can be obtained based on the type of the external interface. After determining the type, the processing module controls the first and second control switches to open or close to switch modes, processing the voltage across the sampling resistor according to the corresponding model. Since the data processed by the processing module is digital, while the voltage across the sampling resistor is analog, it needs to be converted from analog to digital first. If the processing module integrates an analog-to-digital converter, it can directly process the voltage data. If the processing module cannot perform analog-to-digital conversion, an ADC module needs to be added before the processing module.

Claims

1. A multi-type analog input acquisition circuit, characterized by, The processing module and the acquisition module for realizing voltage acquisition, current acquisition and resistance acquisition, the acquisition module comprising a sampling resistor, the sampling resistor being used to connect with the output terminal of the sensor to be tested to acquire the output signal of the sensor to be tested, the processing module being used to acquire the voltage across the sampling resistor to obtain the output signal of the sensor to be tested, the sampling resistor further being connected with a constant current source, the constant current source being used to provide current when the sensor to be tested outputs resistance, the processing module obtaining the resistance output by the sensor to be tested according to the acquired voltage across the sampling resistor, the resistance value of the sampling resistor and the current of the constant current source; The processing module is further used to directly determine the output voltage of the sensor to be tested according to the voltage across the sampling resistor when the sensor to be tested outputs voltage, and to determine the output current of the sensor to be tested according to the voltage across the sampling resistor and the resistance value of the sampling resistor when the sensor to be tested outputs current.

2. The multi-type analog input acquisition circuit according to claim 1, characterized in that, The sampling resistor comprises a first sampling resistor and a second sampling resistor, the first sampling resistor and the second sampling resistor being connected in parallel and used to connect with the output terminal of the sensor to be tested, a second control switch being arranged on the loop in which the second sampling resistor is located, the second control switch being used to be closed when the sensor to be tested outputs current signal, so that the first sampling resistor and the second sampling resistor are connected in parallel and connected with the sensor to be tested, and the second control switch being used to be opened when the sensor to be tested outputs voltage or resistance, so that only the first sampling resistor is connected with the output terminal of the sensor to be tested.

3. The multi-type analog input acquisition circuit according to claim 2, characterized in that, The constant current source is connected to the loop in which the sampling resistor is located through a first control switch, and is used to be closed when the sensor to be tested outputs resistance, so as to provide constant current for the loop in which the sampling resistor is located.

4. The multi-type analog input acquisition circuit according to claim 3, characterized in that, The first control switch and the second control switch are both connected with the processing module, and the processing module is used to control the first control switch and the second control switch according to the type of the output signal of the sensor to be tested.

5. The multi-type analog input acquisition circuit according to claim 1, wherein, The output terminal of the processing module is connected with an external interface, so that the type of the output signal of the sensor to be tested is acquired through the external interface.

6. The multi-type analog input acquisition circuit of claim 1, wherein, The processing module is further connected with a man-machine interface, and is used to acquire the type of the external interface through the man-machine interface, and to determine the type of the output signal of the sensor according to the type of the external interface.

7. The multi-type analog input acquisition circuit according to claim 1, wherein, The processing module is connected with the sampling resistor through a voltage follower circuit, and is used to isolate the voltage signal acquired by the sampling resistor from the processing module.

8. The multi-type analog input acquisition circuit according to claim 3, wherein, The first control switch and the second control switch are transistors or relays.

9. The multi-type analog input acquisition circuit according to claim 1, wherein, The constant current source comprises a controllable switch tube and an operational amplifier circuit, one input terminal of the operational amplifier circuit being connected with a power supply VCC, another input terminal of the operational amplifier circuit being connected with an operational amplifier output terminal, the controllable switch tube being connected in series between the power supply VCC and the acquisition module, a control terminal of the controllable switch tube being connected with the operational amplifier circuit output terminal, so that the controllable switch tube is turned on when receiving the signal sent by the operational amplifier circuit output terminal, and the power supply VCC provides stable current to the acquisition module.

10. A multi-type analog input acquisition device, characterized in that, The circuit board is arranged in the shell, and the multi-type analog quantity input acquisition circuit is arranged on the circuit board.

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