A cable tester

Abstract

The present invention relates to the technical field of aircraft component testing, and in particular to a cable tester comprising: a test interface for connecting a cable to be tested; a test circuit for connecting the cable to be tested via the test interface to perform a cable connectivity test, the test circuit comprising a first microcontroller unit, a second microcontroller unit, and a dynamic relay matrix; the first microcontroller unit being configured to connect to a first set of pins of the cable to be tested via the test interface, and the second microcontroller unit being configured to connect to a second set of pins of the cable to be tested via the test interface; the dynamic relay matrix comprising at least a first relay and a second relay for controlling the connection between the first microcontroller unit and the second microcontroller unit and the test interface by closing the first relay and the second relay, thereby causing the cable tester to enter a cable connectivity test mode; and a power module. The present invention is specifically designed for flexible cable assemblies in CDSS hinge assemblies and can implement automated cable connectivity testing.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft component testing, in particular to a cable tester. Background Art

[0002] Civil aviation systems place extremely high demands on the stability of aircraft components. Any minor fault can trigger a chain reaction, threatening flight safety. Therefore, regular inspections are crucial to ensuring their continued reliability and safety. The Airbus Cockpit Door Surveillance System (CDSS) is a critical system for cockpit safety, and the connectivity of the flexible cable assembly in its hinge assembly is a key component that requires inspection.

[0003] Existing cable testers mostly use single-core microcontroller units (MCUs), which must sequentially handle tasks such as data acquisition, logical judgment, and display. This results in lengthy test cycles, with each frame typically taking ≥1.5 seconds, making it difficult to meet the requirements for rapid aircraft component testing. Furthermore, most existing cable testers can only test cables with a fixed number of cores. They lack the flexibility to adapt to varying requirements in complex multi-channel testing scenarios, such as 47-core cables. Furthermore, existing cable testers have rigid mode switching, lack flexible relay control logic, and lack self-recovery diode detection, resulting in relatively limited functionality. Summary of the Invention

[0004] In order to solve one of the above-mentioned problems in the prior art, the present invention provides a cable tester.

[0005] To achieve the above object, the present invention provides a cable tester, comprising: a test interface, a test circuit and a power supply module;

[0006] The test interface is used to connect a cable to be tested, wherein the cable to be tested includes: a flexible cable configured for a hinge assembly of an Airbus aircraft cockpit door monitoring system;

[0007] The test circuit is used to connect the cable to be tested through the test interface to perform a cable connectivity test, and the test circuit includes a first micro control unit, a second micro control unit and a dynamic relay matrix;

[0008] The first microcontroller unit and the second microcontroller unit are respectively connected to the test interface through the dynamic relay matrix, the first microcontroller unit is used to connect to a first group of pins of the cable to be tested through the test interface, and the second microcontroller unit is used to connect to a second group of pins of the cable to be tested through the test interface, wherein the first group of pins is a part of the pins of the cable to be tested, and the second group of pins is another part of the pins of the cable to be tested;

[0009] The dynamic relay matrix includes at least a first relay and a second relay, and is configured to control the connection between the first micro control unit and the second micro control unit and the test interface by closing the first relay and the second relay, so that the cable tester enters a cable connectivity test mode;

[0010] The power supply module is used to provide power to the cable tester.

[0011] The present invention provides a cable tester specifically designed for 47-core flexible cable assemblies used in CDSS hinge assemblies. It enables automated testing of cable connectivity and self-healing diode performance. By utilizing dual MCU parallel processing technology, a dynamic relay matrix architecture, and a high-precision impedance voltage divider algorithm, the cable tester improves testing efficiency by 40%, keeps the false detection rate to ≤ 0.05%, and significantly reduces the need for manual intervention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a structural diagram of a cable tester provided in Example 1 of the present invention;

[0013] Figure 2 A schematic diagram showing the connection between the cable tester and the cable to be tested provided in Example 1 of the present invention;

[0014] Figure 3 This is a design example diagram of a connector circuit of a test interface provided in Example 1 of the present invention;

[0015] Figure 4 This is another design example diagram of the connector circuit of the test interface provided in Example 1 of the present invention;

[0016] Figure 5 This is an example diagram of a dual MCU circuit design provided in Example 1 of the present invention;

[0017] Figure 6 This is a design example diagram of JT1 in the dynamic relay matrix circuit provided in Example 1 of the present invention;

[0018] Figure 7This is a design example diagram of JT2 in the dynamic relay matrix circuit provided in Example 1 of the present invention;

[0019] Figure 8 This is an example diagram of a specific implementation circuit design of the self-recovery test unit and JT3 provided in Example 1 of the present invention;

[0020] Figure 9 This is a flow chart of a specific test example of the self-recovery diode test provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] Example 1

[0023] This embodiment provides a cable tester specifically designed for use with the 47-core flexible cable assembly in CDSS hinge assemblies. It enables automated testing of cable connectivity and self-restoring diode performance. This flexible cable assembly is typically a Parts Manufacturer Approval (PMA) component, which refers to aviation replacement parts approved by airworthiness authorities such as the FAA / EASA and manufactured by non-third-party manufacturers. The flexible cable assembly is installed on the hinge assembly and is a subassembly of the hinge assembly. It can be fixed to the hinge assembly or embedded within it.

[0024] like Figure 1 As shown, the cable tester provided in this embodiment includes: a test interface, a test circuit and a power supply module.

[0025] In an optional embodiment, the specific structure of the cable tester may include: a chassis body, a chassis cover, a front panel, a display screen, an aviation plug-in interface, a test circuit board and a power module. The test interface of this embodiment can be set on the aviation plug-in interface, and the test circuit can be set on the test circuit board.

[0026] The test interface is used to connect the cable to be tested, including the flexible cable used in the hinge assembly of an Airbus cockpit door monitoring system. Specifically, the test interface can be located on the cable tester's housing or externally, with a data cable interface for flexible connection to the cable to be tested. The test interface must be compatible with the flexible cable to be tested. For example, if the flexible cable has 47 pins, the test interface must include at least 47 pins and be able to adapt to the positions of these 47 pins.

[0027] In an optional embodiment, the cable to be tested may have two ports J1 and J2, and the test interface should also have two connectors, which can be used to connect the two ports of the cable to be tested to form a test loop. Figure 2 One possible connection is shown.

[0028] In an optional embodiment, the test interface can be as follows Figure 3 and 4 The connectors shown have 50 pins each.

[0029] The test circuit is used to connect to the cable under test through a test interface to perform a cable connectivity test. The test circuit includes a first microcontroller unit, a second microcontroller unit, and a dynamic relay matrix. Specifically, the test circuit can utilize a dual-MCU collaborative architecture to perform division of labor. The two microcontrollers can achieve real-time data synchronization via an interface (such as a UART serial port with a baud rate of 115200).

[0030] The first microcontroller unit and the second microcontroller unit are each connected to a test interface via a dynamic relay matrix. The first microcontroller unit is configured to connect to a first set of pins of a cable to be tested via the test interface, and the second microcontroller unit is configured to connect to a second set of pins of the cable to be tested via the test interface. The first set of pins comprises a portion of the pins of the cable to be tested, and the second set of pins comprises another portion of the pins of the cable to be tested. Specifically, the first microcontroller unit and the second microcontroller unit each have a corresponding number of pins for connecting to the pins of the cable to be tested via the pins of the test interface. The number of pins provided depends on the model of the microcontroller unit used. For example, the first microcontroller unit and the second microcontroller unit may be configured as the STC15F2K60S2 model. In this embodiment, only the necessary pins need to be connected; the redundant pins may be left blank. The dynamic relay matrix may be connected between the pins of the test interface and the pins of the first microcontroller unit and the second microcontroller unit to control the paths between the test interface and the first microcontroller unit and the second microcontroller unit.

[0031] In an optional embodiment, the cable under test can be a 47-core flexible cable, with the first group of pins representing the first 24 cores of the cable under test, and the second group of pins representing the last 23 cores. The first microcontroller unit should also have at least 24 pins for connecting to the first 24 cores of the cable under test via the test interface, and the second microcontroller unit should have at least 23 pins for connecting to the last 23 cores of the cable under test via the test interface. By grouping the cables under test for connection and testing, not only does it allow for more flexible adaptation to complex cables, such as the CDSS articulated 47-core flexible cable assembly, but it also enables parallel processing to improve testing efficiency.

[0032] like Figure 5 The figure shows an alternative circuit design example for the first microcontroller unit IC1 and the second microcontroller unit IC2. IC1 pins P01-P24 correspond to connectors 1-1 through 1-24, connecting the first 24 cores of the cable under test. IC2 pins P25-P47 correspond to connectors 1-25 through 1-47, with pins 36 / 37 / 43 disabled, connecting the last 23 cores and the resettable diode test channel. IC1 primarily handles continuity testing of the first 24 cores, while IC2 primarily handles testing of the last 23 cores and the resettable diode, described later.

[0033] It should be noted that Figure 3 and Figure 4 Connectors and Figure 5 The pin labels in the microcontroller are merely names for the pins, which can help understand the interconnection relationship between the connector and the microcontroller pins, but are not limitations on the pins. In a specific embodiment, the connections can be made according to the actual circuit relationship. Figure 3 、 Figure 4 and Figure 5 There may be some vacant pins in the connector and microcontroller unit to facilitate subsequent function expansion.

[0034] The dynamic relay matrix includes at least a first relay and a second relay, and is used to control the connection between the first micro control unit and the second micro control unit and the test interface by closing the first relay and the second relay, so that the cable tester enters the cable connectivity test mode. Figure 6 and 7 A specific circuit design example of a dynamic relay matrix is given. Figure 6 and 7 The first relay JT1 and the second relay JT2 are connected to the test interface. Figure 3 、 Figure 4 and Figure 5 .

[0035] In a specific embodiment, when not powered or in standby mode, the contacts of JT1 / JT2 are in a normally open (disconnected) state. The triggering condition for the relay state switching can be controlled by the power mode and / or the control button. For example, a button TEST1 (which can be a physical button, soft key, or virtual button) can be set on the cable tester to control the opening and closing of relays JT1 / JT2. The specific logic is as follows: After the AC power of the entire device is turned on, the TEST1 button is triggered, the JT1 / JT2 relays are energized (closed), and the moving contacts (such as JT1-K1 / JT2-K1) automatically connect the cable test circuit, thereby controlling the cable tester to enter the cable connectivity test mode.

[0036] The power module provides power to the cable tester. Specifically, it operates within the AC voltage range of 100V-240V / 50-60Hz and can output DC power of 12V / 3A or 5V / 2A to power various components of the cable tester. The power module can use the GA46-2DB model. It can integrate a heat dissipation module and temperature compensation function module to improve the reliability of test results in extreme temperature environments.

[0037] The cable tester provided in this embodiment, based on the coordinated control of dual microcontroller units (MCUs) and dynamic relays, is specifically designed for the flexible cable assemblies used in the hinge assembly of the Airbus Cockpit Door Surveillance System (CDSS). It enables automated cable connectivity testing. By utilizing dual-MCU parallel processing technology and a dynamic relay matrix structure, the tester improves testing efficiency by 40%, significantly reducing the need for manual intervention.

[0038] In one optional embodiment, when the cable tester enters cable continuity test mode, the first microcontroller unit is configured to scan the voltage level of each pin in the first group of pins, determine the on / off status of the first group of pins based on the voltage level of each pin in the first group of pins, generate real-time synchronization data based on the on / off status information of the first group of pins, and transmit the real-time synchronization data to the second microcontroller unit via a preset communication protocol format. Specifically, the first microcontroller unit is primarily responsible for continuity testing of the first 24-core cable (pins P01-P24), and then transmits the open / closed status to the second microcontroller unit via the UART serial port. The first microcontroller unit may not directly output external data, but only transmits raw data. Of course, the first microcontroller unit can also directly output data in real time, depending on the specific design scenario requirements. The judgment threshold for the continuity test can be determined based on the actual circuit conditions: a low level is considered an open circuit, and a high level is considered a closed circuit. For example, the judgment threshold for the continuity test can be set to a low level ≤ 0.8V and a high level ≥ 2.0V. By sharing the test process through the first micro control unit, the connectivity (on / off) of the cable conductor can be quickly detected and the cable break can be located, thereby improving the detection efficiency.

[0039] In one optional embodiment, a second microcontroller unit is configured to scan the level of each pin in the second pin group, determine the on / off status of the second pin group based on the level of each pin in the second pin group, receive real-time synchronous data, obtain the on / off status information of the first pin group from the real-time synchronous data, and integrate and output the on / off status information of the first and second pin groups. Specifically, the second microcontroller unit is required to scan pins P25-P47 (including P25-P28), rather than relying solely on data from the first microcontroller unit. P25-P28 are test channels of the second microcontroller unit, directly connected to the last 23 pins of the cable, and their level status must be independently scanned. Therefore, the second microcontroller unit's task is to receive real-time synchronous data from the first microcontroller unit, simultaneously scan the level of the last 23 pins for continuity determination, and integrate the test results of all 47 pins (the first 24 pins are scanned by the first microcontroller unit, and the last 23 pins are scanned by the second microcontroller unit itself). Based on this integrated data, the second microcontroller unit controls the output of the test results. Test results can be displayed in a variety of ways, including text, images, and voice. For example, if the cable tester is equipped with a display, the cable's shape and pins can be simulated on the screen, with green / red markings indicating whether the pins are on or off, allowing the user to intuitively read the test results. Centralized control through a second microcontroller (MCU) prevents signal conflicts or asynchronous refresh cycles caused by simultaneous operation of the display by two MCUs. As the control core, the second MCU ensures that all test results are rendered simultaneously, maintaining data integrity and improving the user experience.

[0040] In one optional embodiment, the real-time synchronization data includes at least a frame header, a data segment, and a check code, with the on / off status information of the first group of pins stored in the data segment. Specifically, the format of the real-time synchronization data can be determined as needed, with key information stored in the data segment. Table 1 shows a specific example of a real-time synchronization data format. In addition to the frame header, data segment, and check code, it may also include functional fields such as a function code for defining the operation type and a field for defining the data length.

[0041] Table 1 Example of real-time synchronization data format

[0042]

[0043] In an optional embodiment, the first micro control unit and the second micro control unit are connected to the test interface via an impedance voltage divider circuit. Figure 3 and Figure 4 As can be seen, each pin of the connector circuit is connected to a resistor. The pins of the first and second microcontroller units can be connected to the connector pins via the series resistors. Using the series resistor network to collect the cable loop voltage in real time improves detection accuracy, reaching ±0.1%.

[0044] In an optional embodiment, the test circuit further includes: a self-recovery test unit; the dynamic relay matrix further includes a third relay, which remains closed when the cable tester is in cable connectivity test mode; the self-recovery test unit is connected to the second microcontroller unit via the third relay; the second microcontroller unit is further configured to connect to a self-recovery diode in the cable to be tested via a test interface; the dynamic relay matrix is further configured to disconnect the first and second relays and switch the third relay from a closed state to an open state to control the connection between the self-recovery test unit and the second microcontroller unit, thereby causing the cable tester to enter self-recovery test mode. Specifically, the self-recovery diode is located on the flexible cable assembly and is configured to provide overcurrent protection and self-recovery for the flexible cable to ensure the performance stability of the flexible cable. The cable tester of the present invention can also detect the self-recovery diode. To ensure the normal operation of both detection modes, the cable connectivity test and self-recovery test modes can be switched separately using the dynamic relay matrix. By regularly detecting the performance of the self-recovery diode in the flexible cable, the holding current, trip current, and self-recovery performance of the self-recovery diode can be verified in a timely manner, diode failure issues can be detected, and maintenance efficiency can be improved.

[0045] In a specific embodiment, the self-recovery test unit can be connected to the power module and the second micro control unit, obtain power through the power module, and implement the self-recovery test through the second micro control unit. The dynamic relay matrix can also include a third relay JT3. The specific implementation of the self-recovery test unit and JT3 can be as follows Figure 8 As shown in the circuit. When not powered or in standby state, the contacts of JT3 are in the normally closed / closed state. The triggering condition for the state switching of the JT3 relay can be controlled by a button. For example, a control button TEST2 (which can be a physical button, soft key or virtual button) can be set on the cable tester to control the opening and closing of the relay JT3. The specific logic is as follows: When the external test power supply is connected, the TEST2 button is triggered, the JT3 relay is energized (the normally closed contact is disconnected), and the power supply to the MCU and the cable continuity test circuit is cut off. The JT1 / JT2 relay is released (maintains the normally open state), and the static contact connects the self-recovery diode test circuit. In addition, there can be multiple channels for the self-recovery test, such as Figure 8 The F1-F4 ports represent four self-recovery test channels, which can complete the self-recovery test separately or simultaneously.

[0046] In an optional embodiment, when the cable tester enters the self-recovery test mode, the power module is used to connect the working current to the self-recovery diode through the self-recovery test unit; the self-recovery test unit is used to detect the on or off state of the self-recovery diode under the working current. If the self-recovery diode is in the on state, the power module is controlled to connect the step current to the self-recovery diode to detect the on or off state of the self-recovery diode under the step current, wherein the step current is greater than the working current. Specifically, the working current can allow the external power supply to be adjusted within the range of 0-3.2A. In a specific test example, the working current can be set to 0.25A and the step current can be set to 0.4A. By verifying the performance of the diode through the current step, it can be tested whether the diode has an overcurrent protection function.

[0047] In one optional embodiment, upon detecting that the recovery diode has entered the disconnected state, the power module is further configured to re-apply operating current to the recovery diode via the recovery test unit. The recovery test unit is further configured to detect whether the recovery diode has returned to the on state. After the diode has tripped due to overcurrent protection, the diode's performance can be verified by applying normal operating current to test its self-recovery function.

[0048] Figure 9 The flowchart of a specific test example of the self-recovery diode test can intuitively show the specific process of the self-recovery diode test.

[0049] Example 2

[0050] This embodiment provides an example of using the cable tester of the present invention to perform connectivity testing on a 47-core cable and data verification, as follows:

[0051] 1. Test conditions

[0052] Cable type: 47-core cable dedicated to CDSS hinge assembly.

[0053] Ambient temperature: 25°C.

[0054] 2. Testing process

[0055] (1) Connect the 47-core cable for the CDSS hinge assembly to the J1 and J2 interfaces and start the cable connectivity test mode;

[0056] (2) The cable tester completes the scan of all core wires within 1 second and marks two red break points on the display screen;

[0057] (3) The test report was exported and the false positive rate was calculated to be 0.03%.

[0058] 3. Comparison of test results

[0059]

[0060] Example 3

[0061] This embodiment provides an example and data verification of using the cable tester of the present invention to test the performance of the self-recovery diode of a 47-core cable, as follows:

[0062] 1. Test conditions

[0063] Cable type: 47-core cable dedicated to CDSS hinge assembly.

[0064] Ambient temperature: -20°C.

[0065] External power supply: 0-32V adjustable DC power supply.

[0066] 2. Testing process

[0067] (1) Connect a 47-core cable at -20°C.

[0068] (2) Inject 0.40A current from the external power supply, observe the ammeter, and record the trip time as 1.8 seconds.

[0069] (3) Restart the device after power failure, adjust the current to 0.25A, verify that the diode is restored to conduction, and record the recovery time as 4.5 seconds.

[0070] 3. Comparison of test results

[0071]

[0072] In the description of the embodiments of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "center", "top", "bottom", "top", "bottom", "inside", "outside", "inner side", "outer side" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. Among them, "inside" refers to an internal or enclosed area or space. "Periphery" refers to the area surrounding a specific component or specific area.

[0073] In the description of the embodiments of the present invention, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Therefore, a feature specified as "first," "second," "third," or "fourth" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0074] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," and "assembled" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0075] In the description of the embodiments of the present invention, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0076] In describing the embodiments of the present invention, it should be understood that "-" and "~" represent a range between two values, and the range includes the endpoints. For example, "AB" represents a range greater than or equal to A and less than or equal to B. "A~B" represents a range greater than or equal to A and less than or equal to B.

[0077] In describing the embodiments of the present invention, the term "and / or" is used herein to describe a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. Furthermore, the character " / " is generally used herein to indicate that the associated objects are in an "or" relationship.

[0078] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A cable tester, characterized in that: include: Test interface, test circuit and power supply module; The test interface is used to connect a cable to be tested, wherein the cable to be tested includes: a flexible cable configured for a hinge assembly of an Airbus aircraft cockpit door monitoring system; The test circuit is used to connect the cable to be tested through the test interface to perform a cable connectivity test, and the test circuit includes a first micro control unit, a second micro control unit and a dynamic relay matrix; The first microcontroller unit and the second microcontroller unit are respectively connected to the test interface through the dynamic relay matrix, the first microcontroller unit is used to connect to a first group of pins of the cable to be tested through the test interface, and the second microcontroller unit is used to connect to a second group of pins of the cable to be tested through the test interface, wherein the first group of pins is a part of the pins of the cable to be tested, and the second group of pins is another part of the pins of the cable to be tested; The dynamic relay matrix includes at least a first relay and a second relay, and is configured to control the connection between the first micro control unit and the second micro control unit and the test interface by closing the first relay and the second relay, so that the cable tester enters a cable connectivity test mode; The power supply module is used to provide power to the cable tester; Among them, when the cable tester enters the cable connectivity test mode, the first microcontroller unit is used to scan the level value of each pin in the first group of pins, judge the on-off status information of the first group of pins according to the level value of each pin in the first group of pins, and generate real-time synchronization data according to the on-off status information of the first group of pins, and send the real-time synchronization data to the second microcontroller unit through a preset communication protocol format; the second microcontroller unit is used to scan the level value of each pin in the second group of pins, judge the on-off status information of the second group of pins according to the level value of each pin in the second group of pins, and receive the real-time synchronization data, obtain the on-off status information of the first group of pins in the real-time synchronization data, and integrate and output the on-off status information of the first group of pins and the second group of pins.

2. The cable tester according to claim 1, characterized in that: The cable to be tested is a 47-core flexible cable, the first group of pins are the first 24-core pins of the cable to be tested, and the second group of pins are the last 23-core pins of the cable to be tested.

3. The cable tester according to claim 2, characterized in that: The first micro control unit has at least 24 pins, which are used to connect to the first 24 pins of the cable to be tested through the test interface; The second micro control unit has at least 23 pins, which are used to be connected to the last 23 pins of the cable to be tested via the test interface.

4. The cable tester according to claim 1, characterized in that: The real-time synchronization data at least includes: a frame header, a data segment and a check code, and the on-off status information of the first group of pins is stored in the data segment.

5. The cable tester according to claim 1, characterized in that: The first micro control unit and the second micro control unit are respectively connected to each pin of the test interface through an impedance voltage divider circuit.

6. The cable tester according to any one of claims 1 to 5, characterized in that: The test circuit further includes: a self-recovery test unit; The dynamic relay matrix further includes a third relay, wherein the third relay remains in a closed state when the cable tester is in the cable continuity test mode; The self-recovery test unit is connected to the second micro control unit via the third relay; The second micro control unit is further configured to connect to the self-recovery diode in the cable to be tested through the test interface; The dynamic relay matrix is also used to disconnect the first relay and the second relay, and switch the third relay from a closed state to an open state to control the connection between the self-recovery test unit and the second micro control unit, so that the cable tester enters the self-recovery test mode.

7. The cable tester according to claim 6, characterized in that: When the cable tester enters the self-recovery test mode, the power supply module is used to connect the working current to the self-recovery diode through the self-recovery test unit; The recovery test unit is used to detect the on or off state of the recovery diode under the working current. If the recovery diode is in the on state, the power supply module is controlled to connect a step current to the recovery diode to detect the on or off state of the recovery diode under the step current, wherein the step current is greater than the working current.

8. The cable tester according to claim 7, characterized in that: When it is detected that the self-recovery diode enters the disconnected state, the power supply module is further used to reconnect the working current to the self-recovery diode through the self-recovery test unit; The self-recovery test unit is further used to detect whether the self-recovery diode has recovered to a conducting state.

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