A dual mode resistance switchable input detection circuit

Abstract

The utility model discloses a kind of switchable input detection circuit of dual-mode resistance, it is related to input detection circuit technical field, and the circuit includes: including: power control circuit, according to the power control signal received and access different size direct current power supply, and enter corresponding input detection mode;GND control circuit, according to the ground control signal received and access corresponding ground mode with input detection mode;Detection control circuit, detection control circuit is connected power control circuit and GND control circuit respectively, and it is used to switch between the conduction state and the cut-off state between direct current power supply and detection pin;Detection circuit, detection circuit connects detection control circuit, for connecting corresponding two to be measured pins respectively under different input detection mode, and the detection signal of output detection result;The circuit can be widely used in automobile wiring harness plug, contact impedance detection, industrial connector, micro short circuit troubleshooting, consumer electronics, PCB wiring on-off and other test scenes.

Description

Technical Field

[0001] This utility model relates to the field of input detection circuit technology, and more specifically, it relates to a switchable input detection circuit with dual-mode resistance. Background Technology

[0002] In the automotive electronic switch manufacturing field, reliable testing of electrical connections between port pins is a core process for ensuring the safe operation of the entire vehicle's electronic system. Traditional testing methods mainly use continuity testing to identify direct short-circuit faults (resistance < 1Ω) between pins. However, with the increasing integration of automotive electronic systems, the industry has found that when there are abnormal medium-resistance connections (typically 0.1-5kΩ) between pins that are not completely short-circuited, the current testing system cannot effectively identify sub-healthy connection states with contact impedance. Such abnormal resistance can lead to signal transmission distortion, parasitic current consumption, and logic level deviation. In actual vehicles, the proportion of electronic switch failures caused by such defects in after-sales claims is also increasing. The range of existing multi-channel switch testing technologies cannot meet the relevant standards for detecting micro-impedance faults. Therefore, developing intelligent testing solutions with dynamic impedance analysis capabilities has become a key technical requirement for improving the reliability of automotive electronic switches. Utility Model Content

[0003] The purpose of this invention is to provide a switchable input detection circuit with dual-mode resistance to solve the problems existing in the background art.

[0004] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0005] This application provides a switchable input detection circuit with dual-mode resistance values, including:

[0006] The power control circuit connects to DC power supplies of different sizes according to the received power control signals and enters the corresponding input detection mode.

[0007] The GND control circuit connects to the grounding mode corresponding to the input detection mode based on the received grounding control signal.

[0008] The detection control circuit is connected to the power control circuit and the GND control circuit respectively, and is used to switch between the on and off states between the DC power supply and the detection pin.

[0009] The detection circuit is connected to the detection control circuit. It is used to connect the corresponding two pins to be tested under different input detection modes and output the detection signal of the detection result.

[0010] Based on the above technical solution, the present invention can be further improved as follows.

[0011] Furthermore, the aforementioned power control circuit includes diode D1, resistors R1, R2, R3, and R4, transistor Q1, transistor Q2, and relay K1, which are connected together.

[0012] Furthermore, the input terminal of the aforementioned diode D1 forms an input port for receiving power control signals, and the output terminal of diode D1 is connected to one end of resistor R3; the base of transistor Q2 is connected to the other end of resistor R3 and one end of resistor R4 respectively, and the other end of resistor R4 is connected to one end of relay K1 coil and the emitter of transistor Q2 respectively; the collector of transistor Q2 is connected to one end of resistor R2.

[0013] The base of transistor Q1 is connected to the other end of resistor R2 and one end of resistor R1, the other end of resistor R1 is connected to the collector of transistor Q1, and the emitter of transistor Q1 is connected to the other end of the coil of relay K1.

[0014] The contacts of relay K1 are connected to a 5V power supply and a 24V power supply respectively. When relay K1 is energized, it is connected to a 24V power supply, and when relay K1 is de-energized, it is connected to a 5V power supply. When connected to a 5V power supply, a voltage divider resistor R5 is also connected.

[0015] Furthermore, the aforementioned GND control circuit includes diode D2, resistors R6, R7, R8, and R9, transistors Q3 and Q4, and relay K2, which are connected in a relationship.

[0016] Furthermore, the input terminal of the aforementioned diode D2 forms an input port for receiving the grounding control signal, and the output terminal of the diode D2 is connected to one end of the resistor R8; the base of the transistor Q4 is connected to the other end of the resistor R8 and one end of the resistor R9, and the other end of the resistor R9 is connected to one end of the relay K2 coil and the emitter of the transistor Q4; the collector of the transistor Q4 is connected to one end of the resistor R7.

[0017] The base of transistor Q3 is connected to the other end of resistor R7 and one end of resistor R6, the other end of resistor R6 is connected to the collector of transistor Q3, and the emitter of transistor Q3 is connected to the other end of the coil of relay K2.

[0018] When relay K2 is energized, it is grounded through voltage divider resistor R10; when relay K2 is de-energized, it is directly grounded. The grounding modes include grounding through voltage divider resistor R10 and direct grounding.

[0019] Furthermore, the above-mentioned input detection modes include resistance input detection mode and AD input detection mode, and it is resistance input detection mode when connected to a 24V power supply and resistance input detection mode when connected to a 5V power supply.

[0020] Furthermore, the aforementioned detection and control circuit includes a control power supply circuit and a control GND circuit.

[0021] Furthermore, the aforementioned control power supply circuit includes diode D3, diode D4, resistors R11, R12, R13, and R14, transistor Q5, and transistor Q6, wherein:

[0022] The base of transistor Q5 is connected to one end of resistor R11 and one end of resistor R12, respectively. The other end of resistor R11 is connected to the emitter of transistor Q5. The base of transistor Q6 is connected to one end of resistor R13 and one end of resistor R14, respectively. The other end of resistor R13 is connected to the emitter of transistor Q5. The emitters of transistors Q5 and Q6 are also connected to the corresponding contacts of relay K1 that are connected to different DC power supplies.

[0023] The collectors of transistors Q5 and Q6 are connected to the input terminals of diodes D3 and D4, respectively. The output terminals of diodes D3 and D4 are both connected to the control GND circuit and the detection circuit.

[0024] Furthermore, the aforementioned control GND circuit includes resistors R15, R16, R17, and R18, transistor Q7, and transistor Q8, wherein:

[0025] The base of transistor Q7 is connected to one end of resistor R15 and one end of resistor R16 respectively. The other end of resistor R16 is grounded. The base of transistor Q7 is connected to the output terminal of diode D3.

[0026] The base of transistor Q8 is connected to one end of resistor R17 and one end of resistor R18 respectively. The other end of resistor R18 is grounded. The base of transistor Q8 is connected to the output terminal of diode D4.

[0027] The emitters of transistors Q7 and Q8 are also connected to the corresponding contacts of relay K2 with different grounding modes.

[0028] Furthermore, the aforementioned detection circuit includes resistor R19, resistor R20, capacitor C1, and capacitor C2, wherein:

[0029] One end of resistor R19 is connected to the output of diode D3, and the other end of resistor R19 outputs the first signal and is connected to one end of capacitor C1. The other end of capacitor C1 is grounded.

[0030] One end of resistor R20 is connected to the output of diode D4, and the other end of resistor R20 outputs a second signal and is connected to one end of capacitor C2. The other end of capacitor C2 is grounded.

[0031] Compared with the prior art, the present invention has at least the following beneficial effects:

[0032] 1. This switchable input detection circuit is comprehensive, supporting resistance measurement and covering fault modes such as short circuit, poor contact, open circuit, and abnormal resistance connection. It also features fast response and high reliability, high-speed switching control, and a transistor switching time of <100ns, ensuring accurate detection timing. Furthermore, the flexible and adjustable detection logic allows for custom impedance judgment thresholds by adjusting the voltage divider resistance or VCC voltage.

[0033] 2. It can switch between resistance measurement and AD acquisition modes to detect abnormal resistance connections and AD anomalies between multiple channels. The circuit structure is simple, consisting of a small number of components, and is inexpensive. Only four transistors and one sampling resistor are needed to build the core detection circuit. It supports multiplexing, increases the number of circuits, and performs matrix scanning of multi-pin products. At the same time, this circuit has a wide range of applications, with typical application scenarios including automotive wiring harness plugs, contact impedance detection, industrial connectors, micro short circuit troubleshooting, consumer electronics, and PCB trace continuity testing. Attached Figure Description

[0034] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0035] Figure 1 This is a schematic diagram of the connection of the power control circuit in an embodiment of this utility model;

[0036] Figure 2 This is a schematic diagram of the connection of the GND control circuit in an embodiment of this utility model;

[0037] Figure 3 This is a schematic diagram of the connection of the detection control circuit in an embodiment of this utility model;

[0038] Figure 4 This is a schematic diagram of the connection of the detection circuit in an embodiment of this utility model;

[0039] Figure 5 This is a structural block diagram of the switchable input detection circuit in an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0042] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0043] In the description of the embodiments of this utility model, it should be noted that if terms such as "upper", "lower", "left", "right", "vertical", "horizontal", "inner", and "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the utility model product is usually placed in during use, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0044] Furthermore, the use of terms such as "horizontal," "vertical," and "sag" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0045] In the description of the embodiments of this utility model, "a plurality of" means at least two.

[0046] In the description of the embodiments of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0047] Example 1: Current detection systems cannot effectively identify sub-healthy connection states with contact impedance. Such abnormal resistance leads to signal transmission distortion, parasitic current consumption, and logic level shifts. Furthermore, in actual vehicles, electronic switch failures caused by this defect account for an increasing percentage of after-sales claims. Existing multi-channel switch detection technologies do not meet the relevant standards for detecting micro-impedance faults. Therefore, this example provides a switchable input detection circuit with dual-mode resistance values, such as… Figure 5 As shown, it includes:

[0048] The power control circuit connects to DC power supplies of different sizes according to the received power control signals and enters the corresponding input detection mode.

[0049] The aforementioned power control circuit includes diodes D1, R1, R2, R3, and R4, transistors Q1 and Q2, and relay K1, all connected together. Figure 1 As shown.

[0050] Specifically, see Figure 1 The input terminal of diode D1 forms an input port for receiving power control signals, and the output terminal of diode D1 is connected to one end of resistor R3; the base of transistor Q2 is connected to the other end of resistor R3 and one end of resistor R4, and the other end of resistor R4 is connected to one end of relay K1 coil and the emitter of transistor Q2; the collector of transistor Q2 is connected to one end of resistor R2.

[0051] See Figure 1 The base of transistor Q1 is connected to the other end of resistor R2 and one end of resistor R1, the other end of resistor R1 is connected to the collector of transistor Q1, and the emitter of transistor Q1 is connected to the other end of the coil of relay K1.

[0052] See Figure 1 The contacts of relay K1 are connected to a 5V power supply and a 24V power supply respectively. When relay K1 is energized, it is connected to a 24V power supply, and when relay K1 is de-energized, it is connected to a 5V power supply. When connected to a 5V power supply, a voltage divider resistor R5 is also connected.

[0053] Furthermore, the aforementioned switchable input detection circuit also includes a GND control circuit, which connects to the grounding mode corresponding to the input detection mode based on the received grounding control signal.

[0054] Optionally, the above-mentioned GND control circuit includes diode D2, resistors R6, R7, R8, and R9, transistors Q3 and Q4, and relay K2, which are connected in a specific relationship. Figure 2 As shown.

[0055] SeeFigure 2 The input terminal of diode D2 forms an input port for receiving ground control signals, and the output terminal of diode D2 is connected to one end of resistor R8; the base of transistor Q4 is connected to the other end of resistor R8 and one end of resistor R9, and the other end of resistor R9 is connected to one end of relay K2 coil and the emitter of transistor Q4; the collector of transistor Q4 is connected to one end of resistor R7.

[0056] See Figure 2 The base of transistor Q3 is connected to the other end of resistor R7 and one end of resistor R6, the other end of resistor R6 is connected to the collector of transistor Q3, and the emitter of transistor Q3 is connected to the other end of the coil of relay K2.

[0057] See Figure 2 When relay K2 is energized, it is grounded through voltage divider resistor R10; when relay K2 is de-energized, it is directly grounded. The grounding modes include grounding through voltage divider resistor R10 and direct grounding.

[0058] Optionally, the above input detection modes include resistance input detection mode and AD input detection mode, and the input detection mode is resistance input detection mode when connected to a 24V power supply and resistance input detection mode when connected to a 5V power supply.

[0059] Furthermore, the aforementioned switchable input detection circuit also includes a detection control circuit, which is connected to the power control circuit and the GND control circuit respectively, and is used to switch between the on and off states between the DC power supply and the detection pin.

[0060] The aforementioned detection and control circuit includes a control power supply circuit and a control GND circuit, such as... Figure 3 As shown.

[0061] Optionally, the above control power supply circuit includes diode D3, diode D4, resistors R11, R12, R13, and R14, transistor Q5, and transistor Q6. (See [link to relevant documentation]). Figure 3 ,in:

[0062] The base of transistor Q5 is connected to one end of resistor R11 and one end of resistor R12, respectively. The other end of resistor R11 is connected to the emitter of transistor Q5. The base of transistor Q6 is connected to one end of resistor R13 and one end of resistor R14, respectively. The other end of resistor R13 is connected to the emitter of transistor Q5. The emitters of transistors Q5 and Q6 are also connected to the corresponding contacts of relay K1, which are connected to different DC power supplies. The collectors of transistors Q5 and Q6 are connected to the input terminals of diodes D3 and D4, respectively. The output terminals of diodes D3 and D4 are both connected to the control GND circuit and the detection circuit.

[0063] Optionally, the above-mentioned control GND circuit includes resistors R15, R16, R17, and R18, transistor Q7, and transistor Q8, such as... Figure 3 As shown, where:

[0064] The base of transistor Q7 is connected to one end of resistor R15 and one end of resistor R16, respectively. The other end of resistor R16 is grounded. The base of transistor Q7 is connected to the output terminal of diode D3. The base of transistor Q8 is connected to one end of resistor R17 and one end of resistor R18, respectively. The other end of resistor R18 is grounded. The base of transistor Q8 is connected to the output terminal of diode D4. The emitters of transistors Q7 and Q8 are also connected to the corresponding contacts of relay K2 with different grounding modes.

[0065] Furthermore, the aforementioned switchable input detection circuit also includes a detection circuit connected to the detection control circuit, which is used to connect the corresponding two pins to be tested in different input detection modes and output a detection signal of the detection result.

[0066] Specifically, the detection circuit mentioned above includes resistor R19, resistor R20, capacitor C1, and capacitor C2, as follows: Figure 4 As shown, where:

[0067] One end of resistor R19 is connected to the output terminal of diode D3, and the other end of resistor R19 outputs the first signal and is connected to one end of capacitor C1, and the other end of capacitor C1 is grounded; one end of resistor R20 is connected to the output terminal of diode D4, and the other end of resistor R20 outputs the second signal and is connected to one end of capacitor C2, and the other end of capacitor C2 is grounded.

[0068] Example 2: This application provides a switchable input detection circuit with dual-mode resistance, such as... Figure 5 As shown, it includes a power control circuit, a GND control circuit, a detection control circuit, and a detection circuit. For specific connection relationships, please refer to [link / reference needed]. Figures 1-4 .

[0069] Specifically, the circuit function is further explained below; see [link to relevant documentation]. Figures 1-4 When the power input is 5V, it provides voltage for the AD input detection mode; when the power input is 24V, it provides power for the resistance input detection mode. The voltage divider resistors R5 and R10 mentioned above are used to generate a measurable voltage signal with the test resistor. The resistance threshold can be tested by adjusting the voltage divider resistors. The power control circuit selects the power input mode (5V or 24V). The GND control circuit selects the GND input mode (the difference being that one of them has a voltage divider resistor R10). The detection control circuit controls the state of the power supply to the pin, whether it is on or off. Figure 3 or Figure 4Pins A and B are the ports that connect to the product that needs to be tested.

[0070] The working principle of the switchable input detection circuit provided in this embodiment is as follows:

[0071] When in resistance input detection mode, see [link / reference] Figures 1-4 Power selection: Control signal 1 is high level → Q2 is turned on → Q1 base is pulled low → Q1 is turned on → relay K1 is energized → XVCC is connected to +24V power supply.

[0072] Furthermore, when control signal 2 is high, Q4 is turned on, the base of Q3 is pulled low, Q3 is turned on, relay K2 is energized, and XGND is connected to the R10 detection branch; that is, when relays K1 and K2 are closed simultaneously, the detection circuit switches to the resistance input detection mode.

[0073] For short-circuit detection between pins A and B, during the initialization phase: control signal P1U is set low → Q5 is turned on → pin A outputs a high level (V_A≈XVCC). Control signal P2D is set high → Q8 is turned on → pin B is forcibly pulled low (V_B≈0V). In normal state (pins A and B are not connected): pin B remains low due to the pull-down resistor → the detection circuit outputs signal 2 as low. In short-circuit fault state (pins A and B are directly connected): the high level of pin A is transmitted to pin B through the short-circuit point → the voltage of pin B rises to V_B≈VCC, and the detection circuit outputs signal 2 as high (logic "1") after comparison. R20 limits the short-circuit current (VCC / R20). The states between ports A and B are: logic "1", abnormal connection resistance value; logic "2", stage state; logic "3", short circuit.

[0074] For detecting abnormal resistance between pins A and B, if an abnormal resistance Rs exists between pins A and B, Rs and the detection resistor R10 form a series voltage divider circuit, and the detected voltage V at pin B... B The calculation formula is: V B = (R10 / (R10+Rs))×XVCC, By adjusting the resistance value of R10, the voltage division ratio can be changed, thus achieving precise adjustment of the Rs detection threshold. The upper limit threshold of Rs is R. th The calculation formula is: R th = R10×(VCC / V th -1), where V th This is a high-level trigger voltage.

[0075] It should be noted that the accuracy class and temperature coefficient of the voltage divider resistor R10 need to be considered in the specific implementation.

[0076] Furthermore, when in AD input detection mode, such as Figures 1-4As shown, the power selection is as follows: control signal 1 is low level → Q2 is cut off → Q1 base is pulled high → Q1 is cut off → relay K1 is released → the system is connected to +5V power.

[0077] When control signal 2 is low, Q4 is cut off, the base of Q3 is pulled high, Q3 is cut off, relay K2 is released, and XGND is connected to GND; that is, relays K1 and K2 are released simultaneously, and the detection circuit switches to AD input detection mode.

[0078] Specifically, setting control signal P1U low turns on Q5, resulting in a high-level output at pin A (V_A≈5V). Setting control signal P2D high turns on Q8, forcing pin B low (V_B≈0V). R5 and the measuring resistor Rs between pins A and B form a series voltage divider circuit. Through the detection circuit at pin A, the output signal 1 voltage V_A is generated. A =(R5 / (R5+Rs))×XVCC, Signal 1 connects to the MUC to identify the AD value and determine the resistance value between pins A and B; the accuracy of the resistance value between pins A and B can be ensured by changing the resistance value of R5.

[0079] In this embodiment, the provided switchable input detection circuit has the following advantages:

[0080] 1. This circuit is comprehensive and can support resistance measurement, covering fault modes such as short circuit, poor contact, open circuit, and abnormal resistance connection;

[0081] 2. Fast response and high reliability, high-speed switching control: transistor switching time <100ns, ensuring accurate detection timing;

[0082] 3. Flexible and adjustable detection logic: The impedance judgment threshold can be customized by adjusting the voltage divider resistance or VCC voltage.

[0083] 4. Low cost and easy scalability: The core detection circuit can be built with only 4 transistors and 1 sampling resistor. It supports multiplexing, increases the number of circuits, and provides matrix scanning multi-pin products.

[0084] 5. Wide range of applications, typical application scenarios: automotive wiring harness plugs, contact impedance testing, industrial connectors, micro short circuit troubleshooting, consumer electronics, PCB trace continuity testing, etc.

[0085] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A switchable input detection circuit with dual-mode resistance, characterized in that, include: The power control circuit connects to DC power supplies of different sizes according to the received power control signals and enters the corresponding input detection mode. The GND control circuit connects to the grounding mode corresponding to the input detection mode based on the received grounding control signal. A detection control circuit is connected to the power control circuit and the GND control circuit respectively, and is used to switch between the on and off states between the DC power supply and the detection pin. The detection circuit is connected to the detection control circuit and is used to connect the corresponding two pins to be tested under different input detection modes and output the detection signal of the detection result.

2. The switchable input detection circuit with dual-mode resistance according to claim 1, characterized in that, The power control circuit includes diode D1, resistors R1, R2, R3, and R4, transistors Q1 and Q2, and relay K1, which are connected to each other.

3. The switchable input detection circuit with dual-mode resistance according to claim 2, characterized in that, The input terminal of diode D1 forms an input port for receiving power control signals, and the output terminal of diode D1 is connected to one end of resistor R3; the base of transistor Q2 is connected to the other end of resistor R3 and one end of resistor R4, the other end of resistor R4 is connected to one end of relay K1 coil and the emitter of transistor Q2; the collector of transistor Q2 is connected to one end of resistor R2. The base of transistor Q1 is connected to the other end of resistor R2 and one end of resistor R1, the other end of resistor R1 is connected to the collector of transistor Q1, and the emitter of transistor Q1 is connected to the other end of the coil of relay K1. The contacts of the relay K1 are connected to a 5V power supply and a 24V power supply respectively. When the relay K1 is energized, it is connected to a 24V power supply, and when the relay K1 is de-energized, it is connected to a 5V power supply. When the 5V power supply is connected, a voltage divider resistor R5 is also connected.

4. The switchable input detection circuit with dual-mode resistance according to claim 1, characterized in that, The GND control circuit includes diode D2, resistors R6, R7, R8, and R9, transistors Q3 and Q4, and relay K2, which are connected to each other.

5. The switchable input detection circuit with dual-mode resistance according to claim 4, characterized in that, The input terminal of diode D2 forms an input port for receiving ground control signals, and the output terminal of diode D2 is connected to one end of resistor R8; the base of transistor Q4 is connected to the other end of resistor R8 and one end of resistor R9, and the other end of resistor R9 is connected to one end of relay K2 coil and the emitter of transistor Q4; the collector of transistor Q4 is connected to one end of resistor R7. The base of transistor Q3 is connected to the other end of resistor R7 and one end of resistor R6, the other end of resistor R6 is connected to the collector of transistor Q3, and the emitter of transistor Q3 is connected to the other end of the coil of relay K2. When the relay K2 is energized, it is grounded through the voltage divider resistor R10; when the relay K2 is de-energized, it is directly grounded. The grounding modes include grounding through the voltage divider resistor R10 and direct grounding.

6. The switchable input detection circuit with dual-mode resistance according to claim 3, characterized in that, The input detection modes include resistance input detection mode and AD input detection mode. When connected to a 24V power supply, it is in resistance input detection mode, and when connected to a 5V power supply, it is in resistance input detection mode.

7. The switchable input detection circuit with dual-mode resistance according to claim 3, characterized in that, The detection and control circuit includes a control power supply circuit and a control GND circuit.

8. The switchable input detection circuit with dual-mode resistance according to claim 7, characterized in that, The control power supply circuit includes diode D3, diode D4, resistors R11, R12, R13, and R14, transistor Q5, and transistor Q6, wherein: The base of transistor Q5 is connected to one end of resistor R11 and one end of resistor R12, respectively. The other end of resistor R11 is connected to the emitter of transistor Q5. The base of transistor Q6 is connected to one end of resistor R13 and one end of resistor R14, respectively. The other end of resistor R13 is connected to the emitter of transistor Q5. The emitters of transistors Q5 and Q6 are also connected to the corresponding contacts of relay K1 that are connected to different DC power supplies. The collectors of transistor Q5 and Q6 are respectively connected to the input terminals of diode D3 and D4. The output terminals of diode D3 and D4 are both connected to the control GND circuit and the detection circuit.

9. The switchable input detection circuit with dual-mode resistance according to claim 8, characterized in that, The control GND circuit includes resistors R15, R16, R17, and R18, transistor Q7, and transistor Q8, wherein: The base of transistor Q7 is connected to one end of resistor R15 and one end of resistor R16, the other end of resistor R16 is grounded, and the base of transistor Q7 is connected to the output terminal of diode D3. The base of the transistor Q8 is connected to one end of resistor R17 and one end of resistor R18, the other end of resistor R18 is grounded, and the base of the transistor Q8 is connected to the output terminal of diode D4. The emitters of transistors Q7 and Q8 are also connected to corresponding contacts of relay K2 with different grounding modes.

10. A switchable input detection circuit with dual-mode resistance according to claim 8, characterized in that, The detection circuit includes resistor R19, resistor R20, capacitor C1, and capacitor C2, wherein: One end of the resistor R19 is connected to the output terminal of the diode D3, and the other end of the resistor R19 outputs a first signal and is connected to one end of the capacitor C1. The other end of the capacitor C1 is grounded. One end of the resistor R20 is connected to the output terminal of the diode D4, and the other end of the resistor R20 outputs a second signal and is connected to one end of the capacitor C2. The other end of the capacitor C2 is grounded.

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