A cable connection fault diagnosis method and circuit

Abstract

This invention relates to the field of cable fault diagnosis, and discloses a method and circuit for diagnosing cable connection faults. The method specifically includes the following steps: With the auxiliary channel maintaining zero voltage output, the channel under test is switched to constant current source mode and outputs a constant current. A first voltage and a second voltage are obtained by controlling the first and second switches of the channel under test. A comparison resistor is calculated based on the constant current, the first voltage, and the second voltage. This comparison resistor is compared with a first resistor connected to the outer envelope of the cable and a second resistor connected to the core wire. The comparison result is used to determine the connection fault status of the cable's outer envelope and core wire. This invention can accurately diagnose connection faults in the cable's core wire and outer envelope, while maintaining a simple circuit structure and low cost.

Description

Technical Field

[0001] This invention relates to the field of cable fault diagnosis, and in particular to a method and circuit for diagnosing cable connection faults. Background Technology

[0002] In ATE testing systems, voltage and current source boards (VI source boards) and probe cards are connected by numerous cables. In ATE testing machines for high-density memory, DRAM, ASIC, etc., the test heads and probe cards need to be repeatedly connected and disconnected, which can easily lead to cable connection problems.

[0003] VI source cards typically use coaxial cables to connect to probe cards. To improve current carrying capacity, both the core wire and the outer envelope of the coaxial cable are used as the same power channel. In this structure, a break in either the core wire or the outer envelope will result in insufficient current carrying capacity of the power channel, affecting test reliability, and in severe cases, may cause the faulty cable to overheat and burn out.

[0004] There are two main existing methods for diagnosing cable connections. One method uses a constant current source to output current and calculates the cable resistance by measuring the voltage difference at different test points to determine the cable connection status. However, because the resistance of the core wire and the outer envelope is usually very small (typically less than 0.5Ω), and the resistance of the core wire and outer envelope in parallel (typically about 0.25Ω) is very close to the resistance of a single core wire or outer envelope (typically about 0.5Ω), coupled with testing errors, the test results have low discriminative power and are prone to misdiagnosis. More importantly, this method cannot determine whether the fault occurs in the core wire or the outer envelope, which is not conducive to maintenance personnel locating and repairing the problem.

[0005] Another diagnostic method involves adding a relay switch to both the core wire and the outer envelope. While this can pinpoint the fault location, it significantly increases system costs. Considering that a test head typically has over 200 VI channels, adding a relay switch to each channel would increase costs, and high-current relay switches are bulky and difficult to accommodate on a diagnostic board.

[0006] Therefore, there is a need for a method that can accurately diagnose faults in cable cores and outer envelope connections while maintaining a simple circuit structure and low cost. Summary of the Invention

[0007] The purpose of this invention is to provide a cable connection fault diagnosis method and circuit that can accurately diagnose cable core wire and outer envelope connection faults, while maintaining a simple circuit structure and low cost.

[0008] To address the aforementioned technical problems, this invention provides a method and circuit for diagnosing cable connection faults. The method for diagnosing cable connection faults specifically includes the following:

[0009] With the auxiliary channel maintaining zero voltage output, the channel under test is switched to constant current source mode and outputs a constant current. The first voltage and the second voltage are obtained by controlling the first and second switches of the channel under test.

[0010] The comparison resistance is calculated based on the constant current, the first voltage, and the second voltage;

[0011] The comparison resistor is compared with the first resistor connected to the outer envelope of the cable and the second resistor connected to the core wire, and the connection fault of the outer envelope and core wire of the cable is determined based on the comparison result.

[0012] Furthermore, before switching the channel under test to constant current source mode and outputting a constant current while maintaining zero voltage output in the auxiliary channel, and obtaining the first voltage and the second voltage by controlling the first and second switches of the channel under test, the process includes:

[0013] With multiple test channels, two test channels are selected to work, while the remaining test channels are not working. The two test channels are respectively connected to both sides of the relay. At the same time, one of the working test channels is designated as the channel under test, and the other working test channel is designated as the auxiliary channel.

[0014] Furthermore, the condition of maintaining zero voltage output in the auxiliary channel specifically includes: closing the relay, switching the auxiliary channel to constant voltage source mode, opening the first switch of the auxiliary channel, closing the second switch of the auxiliary channel, and setting the output voltage of the auxiliary channel to 0.

[0015] Furthermore, the acquisition of the first voltage and the second voltage specifically includes:

[0016] Close the first switch of the channel under test and open the second switch of the channel under test. Measure the output voltage of the channel under test to obtain the first voltage.

[0017] Open the first switch of the channel under test, close the second switch of the channel under test, measure the output voltage of the channel under test, and obtain the second voltage.

[0018] Furthermore, the step of calculating the comparison resistor based on the constant current, the first voltage, and the second voltage specifically includes: the calculation formula for the comparison resistor is R=(V1-V2) / I, where V1 is the first voltage and V2 is the second voltage.

[0019] Furthermore, the step of comparing the comparison resistor with the first resistor connected to the outer envelope of the cable and the second resistor connected to the core wire, and judging the connection fault of the outer envelope and core wire of the cable based on the comparison result, specifically includes: R1≠R2 and is a known value, the resistance values ​​of R1 and R2 are both greater than the normal resistance of the cable, where R1 is the first resistor and R2 is the second resistor.

[0020] When R=R1, the outer envelope of the cable is normal, but the core wire is faulty;

[0021] When R is greater than MAX(R1, R2), both the outer envelope and the core wire of the cable are faulty.

[0022] When R = R1 × R2 / (R1 + R2), then the outer envelope and core wires of the cable are both normal;

[0023] When R=R2, the core wire of the cable is normal, but the outer envelope is faulty.

[0024] In addition, the present invention also proposes a cable connection fault diagnosis circuit for implementing the cable connection fault diagnosis method as described above, including a voltage and current source board, a cable structure and a diagnostic board;

[0025] The voltage and current source board includes multiple test channels; the cable structure includes multiple sets of cables; the diagnostic board includes a relay, a first resistor, and a second resistor; the cables are disposed between the test channels and the relays.

[0026] The test channel is connected to the cable; the outer envelope of the cable is connected to the relay through a first resistor, and the core wire of the cable is connected to the relay through a second resistor; the test channel, the cable, the first resistor, and the second resistor form a detection circuit, and one end of the detection circuit closer to the first resistor is connected to one end of the relay, and the other end of the relay is connected to the end of another detection circuit closer to the first resistor.

[0027] Furthermore, each group of cables in the cable structure includes a first cable and a second cable; the outer envelope of the first cable is connected to the relay through a first resistor, and the core wire of the first cable is connected to the relay through a second resistor; the core wire of the second cable is connected to the relay; the test channel is connected to the outer envelope and core wire of the first cable, and also to the core wire of the second cable; one end of the relay is connected to the first resistor, the second resistor, and the second cable in one of the detection circuits, and the other end of the relay is connected to the first resistor, the second resistor, and the second cable in another detection circuit.

[0028] Furthermore, the test channel includes: a voltage and current switch, a first switch, and a second switch;

[0029] The voltage and current switch and one end of the first switch are both connected to the outer envelope and core wire of the first cable; the other end of the first switch is connected to one end of the second switch, and the other end of the second switch is connected to the core wire of the second cable.

[0030] Furthermore, the test channel also includes: a digital-to-analog converter, a first operational amplifier, a second operational amplifier, a first buffer, and a selection switch; the voltage and current switch includes a voltage switch and a current switch;

[0031] The first input terminal of the first operational amplifier is connected to the digital-to-analog converter, the second input terminal is connected to one end of the voltage switch and one end of the current switch, and the output terminal is connected to one end of the selection switch and the first input terminal of the second operational amplifier; the second input terminal of the second operational amplifier is connected to the other end of the selection switch, and the output terminal of the second operational amplifier is connected to the other end of the current switch and one end of the first buffer.

[0032] Furthermore, the test channel also includes: a first analog-to-digital converter, a second analog-to-digital converter, a third operational amplifier, and a second buffer;

[0033] The other end of the first buffer is connected to the first analog-to-digital converter; the second analog-to-digital converter is connected to one end of the second buffer, and the other end of the second buffer is connected to the other end of the voltage switch and the output terminal of the third operational amplifier; the first input terminal of the third operational amplifier is connected to the first switch and the second switch; the end of the first switch away from the third operational amplifier is connected to the other end of the selection switch; the end of the second switch away from the third operational amplifier is connected to the core wire of the second cable.

[0034] Through the above technical solution, the present invention has the following beneficial effects:

[0035] By connecting a first resistor and a second resistor to the outer envelope and core wire of the cable respectively, and using the measured comparison resistance to determine the relationship between these resistors, the cable connection fault can be accurately identified. This method eliminates the need for expensive components such as relays or switches; it achieves precise diagnosis of cable connection status simply by adding two resistors, improving the discriminative power and reliability of the test results while avoiding misjudgments.

[0036] By grouping multiple test channels and connecting them via relays, this invention enables efficient parallel testing of multiple cable groups, thereby improving testing efficiency. Furthermore, by designing the first and second resistors to have different resistance values, both greater than the normal resistance of the cable, and comparing the measured resistance values ​​with preset values, it is possible to accurately distinguish between outer envelope faults, core wire faults, or both simultaneously. This provides maintenance personnel with clear fault location information, reducing maintenance complexity and time. Attached Figure Description

[0037] Figure 1 This is a flowchart of a cable connection fault diagnosis method according to an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the overall structure of a cable connection fault diagnosis circuit in one embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of a voltage and current source board with a single test channel in a cable connection fault diagnosis circuit according to an embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of a voltage and current source board with multiple test channels in a cable connection fault diagnosis circuit according to an embodiment of the present invention;

[0041] Figure 5 This is a schematic diagram of a voltage and current source board with eight test channels in a cable connection fault diagnosis circuit according to one embodiment of the present invention.

[0042] In the diagram: 1. Voltage and current source board; 2. Cable structure; 3. Diagnostic board; 4. Selector switch. Detailed Implementation

[0043] Based on the teachings of this specification, those skilled in the art can form new technical solutions through cross-combination of different implementation methods without creating technical contradictions. Such variations should all be considered to fall within the protection scope of this invention.

[0044] The following description, in conjunction with the accompanying drawings, provides a more detailed account of a cable connection fault diagnosis method and circuit according to the present invention, which illustrates preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0045] The invention is described more specifically by way of example in the following paragraphs with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0046] like Figures 1-2 As shown in the figure, this embodiment of the invention proposes a method for diagnosing cable connection faults, which specifically includes the following steps:

[0047] S1. Under the condition that the auxiliary channel m maintains zero voltage output, the channel under test n is switched to constant current source mode and outputs constant current I. The first voltage V1 and the second voltage V2 are obtained by controlling the first switch Sn and the second switch SWn of the channel under test n.

[0048] S2. Calculate the comparison resistor based on the constant current I, the first voltage V1, and the second voltage V2;

[0049] S3. Compare the comparison resistor with the first resistor R1 connected to the outer envelope of the cable and the second resistor R2 connected to the core wire, and determine the connection fault of the outer envelope and core wire of the cable based on the comparison result.

[0050] Before step S1, i.e., before switching the channel under test n to constant current source mode and outputting a constant current I under the condition that the auxiliary channel m maintains zero voltage output, and before obtaining the first voltage V1 and the second voltage V2 by controlling the first switch Sn and the second switch SWn of the channel under test n, the process includes: selecting two test channels to operate while the remaining test channels are not operating, wherein the two test channels are respectively connected to both sides of the relay K0; simultaneously, one of the operating test channels is designated as the channel under test n, and the other operating test channel is designated as the auxiliary channel m. This method of selectively activating test channels can reduce interference during the testing process and improve the accuracy of the test results.

[0051] In a specific example, such as 8 test channels, these test channels can be divided into two groups of 4 test channels each, and for ease of installation, they are placed on both sides of the diagnostic board 3 and connected via relay K0, as shown below. Figure 5 As shown. This group testing method enhances the parallel capabilities of testing and improves testing efficiency. When diagnosing the first group of test channels, two test channels can be selected to work: one as the channel under test (n) and the other as the auxiliary channel (m), while the remaining test channels remain inactive.

[0052] In step S1, i.e., under the condition that the auxiliary channel m maintains zero voltage output, the specific steps include: closing relay K0, switching the auxiliary channel m to constant voltage source mode, opening the first switch Sm of the auxiliary channel m, closing the second switch SWm of the auxiliary channel m, and setting the output voltage of the auxiliary channel m to 0. The purpose of this operation is to establish a reference voltage for the test circuit, providing a stable reference condition for subsequent measurements.

[0053] In this embodiment, obtaining the first voltage V1 and the second voltage V2 specifically includes: closing the first switch Sn of the channel under test n and opening the second switch SWn of the channel under test n, measuring the output voltage of the channel under test n to obtain the first voltage V1; opening the first switch Sn of the channel under test n and closing the second switch SWn of the channel under test n, measuring the output voltage of the channel under test n to obtain the second voltage V2. By controlling the opening and closing states of these two switches, voltage values ​​can be obtained at different test points, making the resistance calculation more accurate.

[0054] In step S2, specifically, calculating the comparison resistor based on the constant current I, the first voltage V1, and the second voltage V2 includes the following formula: the comparison resistor is calculated as R = (V1 - V2) / I. Those skilled in the art will know that the magnitude of the current I can be set according to actual needs. Considering cable characteristics and testing accuracy requirements, a typical value can be selected from an appropriate value within the range of 1mA to 100mA.

[0055] In step S3, the comparison resistor is compared with the first resistor R1 connected to the outer envelope of the cable and the second resistor R2 connected to the core wire, and the connection fault of the outer envelope and core wire of the cable is determined according to the comparison result. Specifically, R1 ≠ R2 and is a known value, and the resistance values ​​of R1 and R2 are both greater than the normal resistance of the cable.

[0056] When R=R1, the outer envelope of the cable is normal, but the core wire is faulty;

[0057] When R is greater than MAX(R1, R2), both the outer envelope and the core wire of the cable are faulty.

[0058] When R = R1 × R2 / (R1 + R2), then the outer envelope and core wires of the cable are both normal;

[0059] When R=R2, the core wire of the cable is normal, but the outer envelope is faulty.

[0060] This embodiment can clearly distinguish various fault conditions by comparing the relationship between the measured value and the preset resistance value, providing precise guidance for maintenance.

[0061] In a specific example, R1 can be set to 10Ω, and R2 can be set to 20Ω, while the normal resistance of the cable is typically around 0.5Ω. This design ensures that R1 and R2 are much larger than the cable's own resistance, making the measurement results primarily reflect the characteristics of R1 and R2, thereby improving the test's discriminative power. Those skilled in the art will understand that the specific values ​​of R1 and R2 can be adjusted according to the actual application scenario and test accuracy requirements, and R1 and R2 can also include other combinations of values ​​besides those in this embodiment, as long as R1 ≠ R2 and both are greater than the cable's normal resistance.

[0062] In an ATE (Automatic Test Equipment) testing system, the voltage and current source board 1 (VI source board) and the probe card are connected by numerous cables. Due to the repeated docking and disengagement of the VI source board and the probe card during testing, cable connection failures are prone to occur. This embodiment addresses this by using resistors of different resistance values ​​connected in series on the cable's outer envelope and core wires. By measuring the differences in resistance values, the location of the fault can be diagnosed, effectively distinguishing between faults in the cable's outer envelope and core wires.

[0063] In addition, combined Figures 2-5 As shown, this embodiment also proposes a cable connection fault diagnosis circuit to implement the cable connection fault diagnosis method described above, including a voltage and current source board 1, a cable structure 2, and a diagnostic board 3.

[0064] Specifically, the voltage and current source board 1 includes multiple test channels; the cable structure 2 includes multiple sets of cables; the diagnostic board 3 includes a relay K0, a first resistor R1, and a second resistor R2; and the cables are arranged between the test channels and the relay K0.

[0065] More specifically, the test channel is connected to the cable; the outer envelope of the cable is connected to the relay K0 via a first resistor R1, and the core wire of the cable is connected to the relay K0 via a second resistor R2; the test channel, cable, first resistor R1, and second resistor R2 form a detection circuit, and one end of the detection circuit near the first resistor R1 is connected to one end of the relay K0, while the other end of the relay K0 is connected to another end of the detection circuit near the first resistor R1. This embodiment requires only a few additional components to achieve accurate diagnosis of cable connection faults.

[0066] In one embodiment, each group of cables in the cable structure 2 includes a first cable and a second cable. Specifically, the outer envelope of the first cable is connected to the relay K0 through a first resistor R1, and the core wire of the first cable is connected to the relay K0 through a second resistor R2; the core wire of the second cable is connected to the relay K0; the test channel connects the outer envelope and core wire of the first cable, and also connects to the core wire of the second cable; one end of the relay K0 is connected to the first resistor R1, the second resistor R2, and the second cable in one of the detection circuits, and the other end of the relay K0 is connected to the first resistor R1, the second resistor R2, and the second cable in another detection circuit.

[0067] In one embodiment, reference continues Figure 3 As shown, the test channel includes: a voltage and current switch, a first switch W1, and a second switch W2.

[0068] Specifically, one end of both the voltage / current switch and the first switch W1 is connected to the outer envelope and core wire of the first cable; the other end of the first switch W1 is connected to one end of the second switch W2, and the other end of the second switch W2 is connected to the core wire of the second cable. This switch configuration allows the test channel to flexibly switch test modes and measurement points, improving testing flexibility.

[0069] In this embodiment, the test channel further includes: a digital-to-analog converter (DAC), a first analog-to-digital converter (ADC1), a second analog-to-digital converter (ADC2), a first operational amplifier (A1), a second operational amplifier (A2), a third operational amplifier (A3), a first buffer (Q1), a second buffer (Q2), and a selection switch (4); the voltage and current switches include a voltage switch (K_V) and a current switch (K_I).

[0070] Specifically, the first input terminal of the first operational amplifier A1 is connected to the digital-to-analog converter (DAC), the second input terminal is connected to one end of the voltage switch K_V and one end of the current switch K_I, and the output terminal is connected to one end of the selection switch 4 and the first input terminal of the second operational amplifier A2; the second input terminal of the second operational amplifier A2 is connected to the other end of the selection switch 4, the output terminal of the second operational amplifier A2 is connected to the other end of the current switch K_I and one end of the first buffer Q1, and the other end of the first buffer Q1 is connected to the first analog-to-digital converter (ADC1); the second analog-to-digital converter (ADC2) is connected to one end of the second buffer Q2, the other end of the second buffer Q2 is connected to the other end of the voltage switch K_V and the output terminal of the third operational amplifier A3; the first input terminal of the third operational amplifier A3 is connected to the first switch W1 and the second switch W2; the end of the first switch W1 away from the third operational amplifier A3 is connected to the other end of the selection switch 4; the end of the second switch W2 away from the third operational amplifier A3 is connected to the core wire of the second cable.

[0071] In this embodiment, the working principle of the VI source board (voltage and current source board 1) is as follows: When the voltage switch K_V is closed and the current switch K_I is open, the operational amplifier A3 measures the voltage at the two input terminals and feeds it back to the operational amplifier A1. At this time, the operational amplifier A1 operates in constant voltage source mode and outputs voltage to the device under test through the voltage and current source lines.

[0072] When voltage switch K_V is open and current switch K_I is closed, operational amplifier A2 measures the voltage at its two input terminals, corresponding to the current on the voltage and current source lines, and feeds this data back to the input of operational amplifier A1. At this time, operational amplifier A1 operates in constant current source mode, outputting current to the device under test through the voltage and current source lines. The channel ADC resource can measure either channel current or channel voltage. When the channel operates in constant current source mode, the first switch W1 and the second switch W2 can select the voltage measurement point.

[0073] In this embodiment, combined with Figures 2-5 As shown, the first step is the preparation stage. Connect the VI source board to the diagnostic board 3. The diagnostic board 3 is equipped with relay K0, first resistor R1, and second resistor R2. Assume that the VI source board has 8 test channels, divided into two groups of 4 channels each, labeled as channel 1 to channel 8.

[0074] Step 2: Testing process for the first group of channels (Channel 1 to Channel 4).

[0075] 1. Select channel 1 as the channel to be tested n, and channel 5 (or channel 6, channel 7, or channel 8) as the auxiliary channel m.

[0076] 2. Close relay K0 to connect channel 1 and channel 5 through relay K0 to form a test circuit.

[0077] 3. Set auxiliary channel 5 to constant voltage source mode, disconnect S5, close SW5, and set the output voltage to 0.

[0078] 4. Set the channel under test 1 to constant current source mode and output a constant current I (e.g., 10mA).

[0079] 5. Close S1 and open SW1, measure the output voltage of channel 1, and obtain the first voltage V1.

[0080] 6. Disconnect S1 and close SW1, measure the output voltage of channel 1, and obtain the second voltage V2.

[0081] 7. Calculate the comparison resistance R = (V1 - V2) / I.

[0082] 8. Determine the cable connection status based on the relationship between the value of R and R1 and R2: If R = R1 (e.g., 10Ω), the outer envelope of the cable in channel 1 is normal, but the core wire is faulty. If R is greater than MAX(R1, R2) (e.g., greater than 20Ω), both the outer envelope and the core wire of the cable in channel 1 are faulty. If R = R1 × R2 / (R1 + R2) (e.g., 6.67Ω), both the outer envelope and the core wire of the cable in channel 1 are normal. If R = R2 (e.g., 20Ω), the core wire of the cable in channel 1 is normal, but the outer envelope is faulty. Record the test results for channel 1.

[0083] Step 3: Continue testing the remaining channels of the first group.

[0084] 1. Switch the channel under test n to channel 2, and keep the auxiliary channel m as channel 5.

[0085] 2. Repeat steps 3 to 8 in step 2 to complete the test of channel 2 and record the results.

[0086] 3. Switch the channel n to be tested to channel 3 and channel 4 in sequence, and repeat the same test process to complete the test of all channels in the first group.

[0087] Step 4: Testing procedures for the second group of channels (channels 5 to 8).

[0088] 1. Select channel 5 as the channel to be tested (n) and channel 1 as the auxiliary channel (m).

[0089] 2. Close relay K0 to connect channel 5 and channel 1 through relay K0 to form a test circuit.

[0090] 3. Set auxiliary channel 1 to constant voltage source mode, disconnect S1, close SW1, and set the output voltage to 0.

[0091] 4. Set the channel under test 5 to constant current source mode and output a constant current I (e.g., 10mA).

[0092] 5. Close S5 and open SW5, measure the output voltage of channel 5, and obtain the first voltage V1.

[0093] 6. Open S5 and close SW5, measure the output voltage of channel 5, and obtain the second voltage V2.

[0094] 7. Calculate the comparison resistance R = (V1 - V2) / I.

[0095] 8. Determine the cable connection status based on the relationship between the value of R and R1 and R2, using the same method as in step two. Record the test results for channel 5.

[0096] Step 5: Continue testing the remaining channels in the second group.

[0097] 1. Switch the channel n to be tested to channel 6, and keep the auxiliary channel m as channel 1.

[0098] 2. Repeat steps 3 to 8 in step 4 to complete the test of channel 6 and record the results.

[0099] 3. Switch the channel n to be tested to channel 7 and channel 8 in sequence, and repeat the same test process to complete the test of all channels in the second group.

[0100] Step 6: After all tests are completed, summarize the cable connection status of each channel based on the test results, and determine which cables need to be repaired or replaced.

[0101] Step 7: If all cable connections are normal, remove diagnostic board 3, connect the VI source board to the probe card, and begin normal chip testing. If a faulty cable is found, repair or replace it, and then perform diagnostic testing again until all cable connections are normal.

[0102] This cyclic testing method in this embodiment fully utilizes the resources of the ATE equipment. Through simple hardware setup and software control, it can achieve accurate diagnosis of the cable connection status of all test channels. The diagnostic process is efficient and orderly, not only detecting the existence of faults but also accurately locating whether the fault occurs in the core wire or the outer envelope, providing clear maintenance guidance for maintenance personnel, thereby improving maintenance efficiency and the reliability of the testing system.

[0103] In summary, the cable connection fault diagnosis method and circuit proposed in this invention have the following advantages:

[0104] By connecting a first resistor and a second resistor to the outer envelope and core wire of the cable respectively, and using the measured comparison resistance to determine the relationship between these resistors, the cable connection fault can be accurately identified. This method eliminates the need for expensive components such as relays or switches; it achieves precise diagnosis of cable connection status simply by adding two resistors, improving the discriminative power and reliability of the test results while avoiding misjudgments.

[0105] By grouping multiple test channels and connecting them via relays, this invention enables efficient parallel testing of multiple cable groups, thereby improving testing efficiency. Furthermore, by designing the first and second resistors to have different resistance values, both greater than the normal resistance of the cable, and comparing the measured resistance values ​​with preset values, it is possible to accurately distinguish between outer envelope faults, core wire faults, or both simultaneously. This provides maintenance personnel with clear fault location information, reducing maintenance complexity and time.

[0106] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A cable connection fault diagnosis circuit, characterized in that, This includes voltage and current source boards, cable structures, and diagnostic boards; The voltage and current source board includes multiple test channels; the cable structure includes multiple sets of cables; the diagnostic board includes a relay, a first resistor, and a second resistor; the cables are disposed between the test channels and the relays. The test channel is connected to the cable; the outer envelope of the cable is connected to the relay through a first resistor, and the core wire of the cable is connected to the relay through a second resistor; the test channel, the cable, the first resistor, and the second resistor form a detection circuit, and one end of the detection circuit closer to the first resistor is connected to one end of the relay, and the other end of the relay is connected to the end of another detection circuit closer to the first resistor; Each cable group in the cable structure includes a first cable and a second cable; the outer envelope of the first cable is connected to the relay through a first resistor, and the core wire of the first cable is connected to the relay through a second resistor; the core wire of the second cable is connected to the relay; the test channel is connected to the outer envelope and core wire of the first cable, and also to the core wire of the second cable; one end of the relay is connected to the first resistor, the second resistor, and the second cable in one of the detection circuits, and the other end of the relay is connected to the first resistor, the second resistor, and the second cable in another detection circuit; The test channel includes: a voltage and current switch, a first switch, and a second switch; one end of the voltage and current switch and one end of the first switch are both connected to the outer envelope and core wire of the first cable; the other end of the first switch is connected to one end of the second switch, and the other end of the second switch is connected to the core wire of the second cable; With multiple test channels, two test channels are selected to work, while the remaining test channels are not working. The two test channels are respectively connected to both sides of the relay. At the same time, one of the working test channels is designated as the channel under test, and the other working test channel is designated as the auxiliary channel. With the auxiliary channel maintaining zero voltage output, the channel under test is switched to constant current source mode and outputs a constant current. A first voltage and a second voltage are obtained by controlling the first and second switches of the channel under test. Specifically, obtaining the first and second voltages includes: closing the first switch of the channel under test, opening the second switch of the channel under test, and measuring the output voltage of the channel under test to obtain the first voltage; opening the first switch of the channel under test, closing the second switch of the channel under test, and measuring the output voltage of the channel under test to obtain the second voltage. The comparison resistor is calculated based on the constant current, the first voltage, and the second voltage. The formula for calculating the comparison resistor is R = (V1 - V2) / I, where V1 is the first voltage and V2 is the second voltage. The comparison resistor is compared with the first resistor connected to the outer envelope of the cable and the second resistor connected to the core wire, and the connection fault of the outer envelope and core wire of the cable is determined according to the comparison result. Specifically, the following conditions are included: R1 ≠ R2 and is a known value; the resistance values ​​of R1 and R2 are both greater than the normal resistance of the cable, where R1 is the first resistance and R2 is the second resistance; when R = R1, the outer envelope of the cable is normal, but the core wire is faulty; when R is greater than MAX(R1, R2), both the outer envelope and the core wire of the cable are faulty; when R = R1 × R2 / (R1 + R2), both the outer envelope and the core wire of the cable are normal; when R = R2, the core wire of the cable is normal, but the outer envelope is faulty.

2. The cable connection fault diagnosis circuit as described in claim 1, characterized in that, The test channel further includes: a digital-to-analog converter, a first operational amplifier, a second operational amplifier, a first buffer, and a selection switch; the voltage and current switch includes a voltage switch and a current switch; The first input terminal of the first operational amplifier is connected to the digital-to-analog converter, the second input terminal is connected to one end of the voltage switch and one end of the current switch, and the output terminal is connected to one end of the selection switch and the first input terminal of the second operational amplifier; the second input terminal of the second operational amplifier is connected to the other end of the selection switch, and the output terminal of the second operational amplifier is connected to the other end of the current switch and one end of the first buffer.

3. The cable connection fault diagnosis circuit as described in claim 2, characterized in that, The test channel also includes: a first analog-to-digital converter, a second analog-to-digital converter, a third operational amplifier, and a second buffer; The other end of the first buffer is connected to the first analog-to-digital converter; the second analog-to-digital converter is connected to one end of the second buffer, and the other end of the second buffer is connected to the other end of the voltage switch and the output terminal of the third operational amplifier; the first input terminal of the third operational amplifier is connected to the first switch and the second switch; the end of the first switch away from the third operational amplifier is connected to the other end of the selection switch; the end of the second switch away from the third operational amplifier is connected to the core wire of the second cable.

4. The cable connection fault diagnosis circuit as described in claim 1, characterized in that, The condition of maintaining zero voltage output in the auxiliary channel specifically includes: closing the relay to switch the auxiliary channel to constant voltage source mode, opening the first switch of the auxiliary channel, closing the second switch of the auxiliary channel, and setting the output voltage of the auxiliary channel to 0.

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