Special cable checking and resistance measuring instrument for heavy-load connector

Abstract

The invention relates to the technical field of cable testing, and particularly discloses a special cable checking and resistance measuring instrument for a heavy-load connector, which comprises a CPU (Central Processing Unit), a direct current source, a relay switching board, a voltage conditioning circuit and a CPLD (Complex Programmable Logic Device), the direct current source, the voltage conditioning circuit and the CPLD are electrically connected with the CPU, and the relay switching board is electrically connected with the direct current source and the voltage conditioning circuit respectively; when cable resistance measurement is carried out, the relay switching board is connected with one end of a to-be-measured cable, and the other end of the to-be-measured cable is completely short-circuited by using the special short-circuit board; the relay switching board enables the direct current source to be electrically connected with a to-be-tested cable. When cable calibration is carried out, the CPLD is connected with one end of a to-be-tested cable through the DB37 female seat, and the other end of the to-be-tested cable is connected with the slave. When cable short circuit fault detection is carried out, the CPLD is connected with one end of a to-be-detected cable through the DB37 female seat, and the other end of the to-be-detected cable is suspended. According to the invention, rapid alignment and resistance measurement of the heavy-load connector can be completed.

Description

Technical Field

[0001] The present invention relates to the technical field of cable testing, and more specifically to a cable calibration and resistance measuring instrument dedicated to a heavy-duty connector. Background Art

[0002] Electrical and non-electrical quantities between secondary equipment and primary equipment, and between secondary equipment, are transmitted through secondary cables. The use of heavy-duty connectors at the ends of secondary cables is an important condition for realizing the trend of modular cable installation in secondary maintenance.

[0003] Common heavy-duty connector secondary cables include 4-core, 10-core, 16-core, etc. After the cable core is connected to the heavy-duty connector, the heavy-duty connector cables at both ends of the cable need to be aligned to prevent wiring errors. In addition, in order to ensure the consistency of each cable and prevent false connection and missed connection failures, the resistance of each cable needs to be tested.

[0004] The traditional testing method is to use a multimeter to calibrate the cables one by one and measure the core resistance of each cable. This traditional method takes a long time to calibrate and measure resistance, is prone to errors, and has low testing efficiency, greatly reducing the installation efficiency of secondary cables equipped with heavy-duty connectors in technical renovation and new construction stations.

[0005] Currently, there is no dedicated test instrument that can measure the alignment and resistance value of heavy-duty connectors. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art, and provides a cable alignment and resistance measuring instrument for a heavy-duty connector, which can quickly align the cable and measure the resistance of the heavy-duty connector.

[0007] As a first aspect of the present invention, a heavy-duty connector dedicated cable calibration and resistance measuring instrument is provided, the heavy-duty connector dedicated cable calibration and resistance measuring instrument comprising a CPU, a DC current source, a relay switching board, a voltage conditioning circuit and a CPLD, the DC current source, the voltage conditioning circuit and the CPLD are all electrically connected to the CPU, and the relay switching board is electrically connected to the DC current source and the voltage conditioning circuit respectively;

[0008] When measuring the cable resistance, the relay switching board is connected to one end of the cable to be tested, and the other end of the cable to be tested is short-circuited using a dedicated short-circuit board; wherein the relay switching board can electrically connect the DC current source to the cable to be tested;

[0009] When calibrating the cable, the CPLD is connected to one end of the cable to be tested via a DB37 female connector, and the other end of the cable to be tested is connected to a slave device;

[0010] When performing cable short-circuit fault detection, the CPLD is connected to one end of the cable to be tested via a DB37 female connector, and the other end of the cable to be tested is suspended.

[0011] Furthermore, when measuring cable resistance, the CPU generates a small DC voltage signal through the built-in DAC, and the small DC voltage signal can drive the DC current source to output a high-precision DC current signal. At this time, the high-precision DC current signal generates a voltage signal proportional to the resistance of the cable to be measured at both ends of the cable to be measured through the relay switching board. After the voltage signal is conditioned by the voltage conditioning circuit, it is collected by the built-in ADC of the CPU.

[0012] Further, when there are 16 cables to be tested, the 16th cable is used as a current return path, and the DC current signal Idc1 output by the DC current source passes through the relay switching board to make the 1st cable and the 16th cable a current loop, and the voltage signal Udc1 at both ends of the 1st cable and the 16th cable is collected through the built-in ADC of the CPU, and the series resistance value Ra1=R1+R16=Udc1 / Idc1 of the 1st cable and the 16th cable is calculated according to Ohm's law; and by analogy, the series resistance values ​​of R2+R16, R3+R16, ..., R15+R16 are calculated respectively; wherein, the series resistance value Ra15=R15+R16 of the 15th cable and the 16th cable;

[0013] Then, the 15th cable is used as a current return path, and the DC current signal Idc2 output by the DC current source is used to make the 1st cable and the 15th cable a current loop through the relay switching board, and the voltage signal Udc2 at both ends of the 1st cable and the 15th cable is collected through the built-in ADC of the CPU, and the series resistance value Rb1=R1+R15=Udc2 / Idc2 of the 1st cable and the 15th cable is calculated according to Ohm's law;

[0014] Since Ra1, Ra15 and Rb1 have been calculated according to Ohm's law, the resistance value R1 of the first cable, the resistance value R15 of the fifteenth cable and the resistance value R16 of the sixteenth cable can be calculated according to the three equations Ra1=R1+R16, Ra15=R15+R16 and Rb1=R1+R15;

[0015] Therefore, since the series resistance values ​​of each cable and the 16th cable have been calculated, and the resistance value R16 of the 16th cable has been calculated, the resistance value R2 of the 2nd cable, the resistance value R3 of the 3rd cable, ..., and the resistance value R14 of the 14th cable can be obtained.

[0016] Furthermore, the CPU calculates the length Ln of each cable to be tested according to the resistance value of each cable to be tested, and the calculation formula is as follows:

[0017] Ln=Rn / (ρ*s)

[0018] Wherein, Rn is the resistance value of each cable to be tested, ρ is the resistivity of each cable to be tested, and s is the wire diameter of each cable to be tested.

[0019] Furthermore, when performing cable calibration, the heavy-duty connector dedicated cable calibration and resistance measuring instrument is set as the host, the GPIO end of the host CPU is connected to the host's CPLD, the host's CPLD is connected to one end of the cable to be tested through a DB37 female connector, and the other end of the cable to be tested is connected to a slave; wherein the slave includes a CPU and a CPLD, and the SEL end and serial port input end of the slave CPU are both connected to the slave's CPLD.

[0020] Further, when there are 16 cables to be tested, the CPU of the host sends the name data of the 16 cables to the CPLD of the host in parallel. After receiving the name data of the 16 cables, the CPLD of the host sends the name data of the 16 cables to the CPLD of the slave in a serial port protocol through the 16 cables, wherein the name data of the 16 cables sent by the host to the slave carries a check code;

[0021] After the CPLD of the slave receives the name data of 16 cables, it controls the CPLD of the slave through the SEL terminal of the slave CPU to send the name data of the corresponding cables to the serial port input terminal of the slave CPU, and then the CPU of the slave parses the received name data of the corresponding cables. If the CPU of the slave verifies that the name data of the corresponding cables is qualified, the slave displays the name data of the corresponding cables.

[0022] Furthermore, when performing cable short-circuit fault detection, it is assumed that there are 16 cables to be tested, and all of the 16 cables to be tested are externally connected with pull-up resistors;

[0023] First, it is detected whether there is a short circuit fault between the first cable and any one of the second to sixteenth cables: the CPU controls the CPLD to set the first cable to a low level. If the CPU reads through the CPLD that any one of the second to sixteenth cables is at a low level, it means that there is a short circuit fault between the first cable and the any one of the cables; if the CPU reads through the CPLD that any one of the second to sixteenth cables is at a high level, it means that there is no short circuit fault between the first cable and the any one of the cables;

[0024] Then, it is detected whether there is a short circuit fault between the second cable and any one of the third to sixteenth cables: the CPU controls the CPLD to set the first cable to a high level, and the CPU controls the CPLD to set the second cable to a low level. If the CPU reads through the CPLD that any one of the third to sixteenth cables is at a low level, it means that there is a short circuit fault between the second cable and the any one of the cables; if the CPU reads through the CPLD that any one of the third to sixteenth cables is at a high level, it means that there is no short circuit fault between the second cable and the any one of the cables;

[0025] Then, it is detected whether there is a short circuit fault between the third cable and any one of the fourth to sixteenth cables: the CPU controls the CPLD to set the first cable and the second cable to a high level, and the CPU controls the CPLD to set the third cable to a low level. If the CPU reads through the CPLD that any one of the fourth to sixteenth cables is at a low level, it means that there is a short circuit fault between the third cable and the any one of the cables; if the CPU reads through the CPLD that any one of the fourth to sixteenth cables is at a high level, it means that there is no short circuit fault between the third cable and the any one of the cables;

[0026] Similarly, it is finally detected whether there is a short circuit fault between the 15th cable and the 16th cable: the CPU controls the CPLD to set the 1st cable to the 14th cable to a high level, and the CPU controls the CPLD to set the 15th cable to a low level. If the CPU reads the 16th cable as a low level through the CPLD, it means that there is a short circuit fault between the 15th cable and the 16th cable; if the CPU reads the 16th cable as a high level through the CPLD, it means that there is no short circuit fault between the 15th cable and the 16th cable.

[0027] Furthermore, the heavy-duty connector dedicated cable calibration and resistance measuring instrument also includes a lithium battery pack, a soft keyboard, an LCD screen, a WIFI chip and a serial FLASH which are electrically connected to the CPU respectively. The lithium battery pack supplies power for the heavy-duty connector dedicated cable calibration and resistance measuring instrument, the soft keyboard is used to set test parameters, the WIFI chip is used to upgrade the test software, and the serial FLASH is used to save resistance test parameters and resistance correction coefficients.

[0028] Furthermore, the lithium battery pack is a large-capacity lithium battery pack.

[0029] Furthermore, the LCD screen is a 480*320 large-screen LCD screen.

[0030] Furthermore, the heavy-duty connector dedicated cable calibration and resistance measuring instrument also includes a battery power detection module electrically connected to the CPU, and the battery power detection module is used to detect the power of the lithium battery pack.

[0031] Furthermore, the heavy-duty connector dedicated cable calibration and resistance measuring instrument is a handheld structure.

[0032] The cable calibration and resistance measuring instrument for heavy-duty connectors provided by the present invention has the following advantages:

[0033] (1) It can support up to 16-core cable pairing, and the pairing time of a single cable is less than 2 seconds;

[0034] (2) It can support resistance testing of up to 16 cables. The measurement time of a single cable is less than 2 seconds. The resistance test can be completed without knowing the impedance value of one of the cables in advance.

[0035] (3) Handheld structure design, small size and light weight;

[0036] (4) With a large LCD screen, human-computer interaction can be achieved through touch screen and soft keyboard;

[0037] (5) Powered by lithium battery, the battery life is more than 12 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0039] Figure 1 The present invention is a block diagram of the principle of a cable calibration and resistance measuring instrument for heavy-duty connectors according to an embodiment of the present invention.

[0040] Figure 2 Schematic diagram of the cable calibration function according to an embodiment of the present invention.

[0041] Figure 3 4 is a schematic diagram of a cable short circuit fault detection according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation method, structure, characteristics and effects of the cable calibration and resistance measuring instrument for heavy-duty connectors proposed by the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0043] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0044] In this embodiment, a cable calibration and resistance measuring instrument for heavy-duty connectors is provided. Figure 1 As shown, the heavy-duty connector dedicated cable calibration and resistance measuring instrument includes a CPU, a DC current source, a relay switching board, a voltage conditioning circuit and a CPLD, wherein the DC current source, the voltage conditioning circuit and the CPLD are all electrically connected to the CPU, and the relay switching board is electrically connected to the DC current source and the voltage conditioning circuit respectively;

[0045] When measuring the cable resistance, the relay switching board is connected to one end of the cable to be tested, and the other end of the cable to be tested is short-circuited using a dedicated short-circuit board; wherein the relay switching board can electrically connect the DC current source to the cable to be tested;

[0046] When calibrating the cable, the CPLD is connected to one end of the cable to be tested via a DB37 female connector, and the other end of the cable to be tested is connected to a slave device;

[0047] When performing cable short-circuit fault detection, the CPLD is connected to one end of the cable to be tested via a DB37 female connector, and the other end of the cable to be tested is suspended.

[0048] Preferably, if Figure 1As shown, when measuring the cable resistance, the CPU generates a small DC voltage signal through the built-in DAC, and the small DC voltage signal can drive the DC current source to output a high-precision DC current signal. At this time, the high-precision DC current signal generates a voltage signal proportional to the resistance of the cable to be measured at both ends of the cable to be measured through the relay switching board. After the voltage signal is conditioned by the voltage conditioning circuit, it is collected by the built-in ADC of the CPU;

[0049] When there are 16 cables to be tested, the 16th cable is used as a current return path, and the DC current signal Idc1 output by the DC current source passes through the relay switching board to make the 1st cable and the 16th cable a current loop, and the voltage signal Udc1 at both ends of the 1st cable and the 16th cable is collected through the built-in ADC of the CPU, and the series resistance value Ra1=R1+R16=Udc1 / Idc1 of the 1st cable and the 16th cable is calculated according to Ohm's law; and by analogy, the series resistance values ​​of R2+R16, R3+R16, ..., R15+R16 are calculated respectively; wherein, the series resistance value Ra15=R15+R16 of the 15th cable and the 16th cable;

[0050] Then, the 15th cable is used as a current return path, and the DC current signal Idc2 output by the DC current source is used to make the 1st cable and the 15th cable a current loop through the relay switching board, and the voltage signal Udc2 at both ends of the 1st cable and the 15th cable is collected through the built-in ADC of the CPU, and the series resistance value Rb1=R1+R15=Udc2 / Idc2 of the 1st cable and the 15th cable is calculated according to Ohm's law;

[0051] Since Ra1, Ra15 and Rb1 have been calculated according to Ohm's law, the resistance value R1 of the first cable, the resistance value R15 of the fifteenth cable and the resistance value R16 of the sixteenth cable can be calculated according to the three equations Ra1=R1+R16, Ra15=R15+R16 and Rb1=R1+R15;

[0052] Therefore, since the series resistance values ​​of each cable and the 16th cable have been calculated, and the resistance value R16 of the 16th cable has been calculated, the resistance value R2 of the 2nd cable, the resistance value R3 of the 3rd cable, ..., and the resistance value R14 of the 14th cable can be obtained.

[0053] Specifically, the CPU calculates the length Ln of each cable to be tested according to the resistance value of each cable to be tested, and the calculation formula is as follows:

[0054] Ln=Rn / (ρ*s)

[0055] Wherein, Rn is the resistance value of each cable to be tested, ρ is the resistivity of each cable to be tested, and s is the wire diameter of each cable to be tested. Wherein, the measurement error of the length Ln is less than 2%.

[0056] Preferably, if Figure 1-2 As shown, when the cable calibration is performed, the heavy-duty connector dedicated cable calibration and resistance measuring instrument is set as the host, the GPIO end of the host CPU is connected to the CPLD of the host, the CPLD of the host is connected to one end of the cable to be tested through the DB37 female connector, and the other end of the cable to be tested is connected to the slave; wherein the slave includes a CPU and a CPLD, and the SEL end and the serial port input end of the slave CPU are both connected to the CPLD of the slave;

[0057] When there are 16 cables to be tested, the name of each cable to be tested is edited through the touch screen and buttons of the host. After pressing the send button of the host, the CPU of the host sends the name data of the 16 cables to the CPLD (complex programmable logic device) of the host in parallel. After the CPLD of the host receives the name data of the 16 cables, it sends the name data of the 16 cables to the CPLD of the slave through the 16 cables in the serial port protocol mode, wherein the name data of the 16 cables sent by the host to the slave carries a check code;

[0058] After the CPLD of the slave receives the name data of 16 cables, it controls the CPLD of the slave through the SEL terminal of the slave CPU to send the name data of the corresponding cables to the serial port input terminal of the slave CPU, and then the CPU of the slave parses the received name data of the corresponding cables. If the CPU of the slave verifies that the name data of the corresponding cables is qualified, the slave displays the name data of the corresponding cables.

[0059] Preferably, if Figure 3 As shown, when performing cable short-circuit fault detection, it is assumed that there are 16 cables to be tested, and all 16 cables to be tested are connected with external pull-up resistors;

[0060] First, it is detected whether there is a short circuit fault between the first cable and any one of the second to sixteenth cables: the CPU controls the CPLD to set the first cable to a low level. If the CPU reads through the CPLD that any one of the second to sixteenth cables is at a low level, it means that there is a short circuit fault between the first cable and the any one of the cables; if the CPU reads through the CPLD that any one of the second to sixteenth cables is at a high level, it means that there is no short circuit fault between the first cable and the any one of the cables;

[0061] For example, firstly, whether there is a short circuit fault between the first cable and the second cable is detected: the CPU controls the CPLD to set the first cable to a low level. If the CPU reads the second cable as a low level through the CPLD, it means that there is a short circuit fault between the first cable and the second cable; if the CPU reads the second cable as a high level through the CPLD, it means that there is no short circuit fault between the first cable and the second cable;

[0062] Then, it is detected whether there is a short circuit fault between the second cable and any one of the third to sixteenth cables: the CPU controls the CPLD to set the first cable to a high level, and the CPU controls the CPLD to set the second cable to a low level. If the CPU reads through the CPLD that any one of the third to sixteenth cables is at a low level, it means that there is a short circuit fault between the second cable and the any one of the cables; if the CPU reads through the CPLD that any one of the third to sixteenth cables is at a high level, it means that there is no short circuit fault between the second cable and the any one of the cables;

[0063] Then, it is detected whether there is a short circuit fault between the third cable and any one of the fourth to sixteenth cables: the CPU controls the CPLD to set the first cable and the second cable to a high level, and the CPU controls the CPLD to set the third cable to a low level. If the CPU reads through the CPLD that any one of the fourth to sixteenth cables is at a low level, it means that there is a short circuit fault between the third cable and the any one of the cables; if the CPU reads through the CPLD that any one of the fourth to sixteenth cables is at a high level, it means that there is no short circuit fault between the third cable and the any one of the cables;

[0064] Similarly, finally, whether there is a short circuit fault between the 15th cable and the 16th cable is detected: the CPU controls the CPLD to set the 1st cable to the 14th cable to a high level, and the CPU controls the CPLD to set the 15th cable to a low level. If the CPU reads the 16th cable as a low level through the CPLD, it means that there is a short circuit fault between the 15th cable and the 16th cable; if the CPU reads the 16th cable as a high level through the CPLD, it means that there is no short circuit fault between the 15th cable and the 16th cable. Theoretically, a total of 16*15 / 2=120 detections are required to detect all short circuit faults between the 16 cables.

[0065] The cable calibration and resistance measuring instrument for heavy-duty connectors provided by the present invention can quickly detect whether short-circuit faults exist between cables and display the number of the cable with the short-circuit fault.

[0066] Preferably, the heavy-duty connector dedicated cable calibration and resistance measuring instrument also includes a large-capacity lithium battery pack, a soft keyboard, a 480*320 large-screen LCD screen, a WIFI chip and a serial FLASH, which are electrically connected to the CPU respectively. The large-capacity lithium battery pack supplies power for the heavy-duty connector dedicated cable calibration and resistance measuring instrument, the soft keyboard is used to set test parameters, the WIFI chip is used to upgrade the test software, and the serial FLASH is used to save resistance test parameters and resistance correction factors.

[0067] Preferably, the heavy-duty connector dedicated cable calibration and resistance measuring instrument further comprises a battery power detection module electrically connected to the CPU, and the battery power detection module is used to detect the power of the lithium battery pack.

[0068] Preferably, the heavy-duty connector dedicated cable calibration and resistance measuring instrument is a handheld structure.

[0069] The cable calibration and resistance measuring instrument for heavy-duty connectors provided by the present invention (1) can support the alignment of up to 16-core cables, and the alignment time of a single cable is less than 2 seconds; (2) can support the resistance test of up to 16 cables, and the measurement time of a single cable is less than 2 seconds, and the resistance test can be completed without knowing the impedance value of one of the cables in advance; (3) has a handheld structure design, small size and light weight; (4) has a large-screen LCD, and can complete human-computer interaction through a touch screen and a soft keyboard; (5) is powered by a lithium battery, and has a battery life of more than 12 hours.

[0070] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A cable calibration and resistance measuring instrument for heavy-duty connectors, characterized in that: The heavy-duty connector dedicated cable calibration and resistance measuring instrument comprises a CPU, a DC current source, a relay switching board, a voltage conditioning circuit and a CPLD, wherein the DC current source, the voltage conditioning circuit and the CPLD are all electrically connected to the CPU, and the relay switching board is electrically connected to the DC current source and the voltage conditioning circuit respectively; When measuring the cable resistance, the relay switching board is connected to one end of the cable to be tested, and the other end of the cable to be tested is short-circuited using a dedicated short-circuit board; wherein the relay switching board can electrically connect the DC current source to the cable to be tested; When calibrating the cable, the CPLD is connected to one end of the cable to be tested via a DB37 female connector, and the other end of the cable to be tested is connected to a slave device; When performing cable short-circuit fault detection, the CPLD is connected to one end of the cable to be tested via a DB37 female connector, and the other end of the cable to be tested is suspended.

2. A cable calibration and resistance measuring instrument for heavy-duty connectors according to claim 1, characterized in that: When measuring the cable resistance, the CPU generates a small DC voltage signal through the built-in DAC, and the small DC voltage signal can drive the DC current source to output a high-precision DC current signal. At this time, the high-precision DC current signal generates a voltage signal proportional to the resistance of the cable to be measured at both ends of the cable to be measured through the relay switching board. After the voltage signal is conditioned by the voltage conditioning circuit, it is collected by the built-in ADC of the CPU; When there are 16 cables to be tested, the 16th cable is used as a current return path, and the DC current signal Idc1 output by the DC current source passes through the relay switching board to make the 1st cable and the 16th cable a current loop, and the voltage signal Udc1 at both ends of the 1st cable and the 16th cable is collected through the built-in ADC of the CPU, and the series resistance value Ra1=R1+R16=Udc1 / Idc1 of the 1st cable and the 16th cable is calculated according to Ohm's law; and by analogy, the series resistance values ​​of R2+R16, R3+R16, ..., R15+R16 are calculated respectively; wherein, the series resistance value Ra15=R15+R16 of the 15th cable and the 16th cable; Then, the 15th cable is used as a current return path, and the DC current signal Idc2 output by the DC current source is used to make the 1st cable and the 15th cable a current loop through the relay switching board, and the voltage signal Udc2 at both ends of the 1st cable and the 15th cable is collected through the built-in ADC of the CPU, and the series resistance value Rb1=R1+R15=Udc2 / Idc2 of the 1st cable and the 15th cable is calculated according to Ohm's law; Since Ra1, Ra15 and Rb1 have been calculated according to Ohm's law, the resistance value R1 of the first cable, the resistance value R15 of the fifteenth cable and the resistance value R16 of the sixteenth cable can be calculated according to the three equations Ra1=R1+R16, Ra15=R15+R16 and Rb1=R1+R15; Therefore, since the series resistance values ​​of each cable and the 16th cable have been calculated, and the resistance value R16 of the 16th cable has been calculated, the resistance value R2 of the 2nd cable, the resistance value R3 of the 3rd cable, ..., and the resistance value R14 of the 14th cable can be obtained.

3. A heavy-duty connector dedicated cable calibration and resistance measuring instrument according to claim 2, characterized in that: The CPU calculates the length Ln of each cable to be tested according to the resistance value of each cable to be tested, and the calculation formula is as follows: Ln=Rn / (ρ*s) Wherein, Rn is the resistance value of each cable to be tested, ρ is the resistivity of each cable to be tested, and s is the wire diameter of each cable to be tested.

4. A heavy-duty connector dedicated cable calibration and resistance measuring instrument according to claim 1, characterized in that: When performing cable calibration, the heavy-duty connector dedicated cable calibration and resistance measuring instrument is set as the host, the GPIO end of the host CPU is connected to the CPLD of the host, the CPLD of the host is connected to one end of the cable to be tested through the DB37 female socket, and the other end of the cable to be tested is connected to the slave; wherein the slave includes a CPU and a CPLD, and the SEL end and the serial port input end of the slave CPU are both connected to the CPLD of the slave; When there are 16 cables to be tested, the CPU of the host sends the name data of the 16 cables to the CPLD of the host in parallel. After receiving the name data of the 16 cables, the CPLD of the host sends the name data of the 16 cables to the CPLD of the slave in serial port protocol through the 16 cables, wherein the name data of the 16 cables sent by the host to the slave carries a check code; After the CPLD of the slave receives the name data of 16 cables, it controls the CPLD of the slave through the SEL terminal of the slave CPU to send the name data of the corresponding cables to the serial port input terminal of the slave CPU, and then the CPU of the slave parses the received name data of the corresponding cables. If the CPU of the slave verifies that the name data of the corresponding cables is qualified, the slave displays the name data of the corresponding cables.

5. The heavy-duty connector dedicated cable calibration and resistance measuring instrument according to claim 1, characterized in that: When performing cable short-circuit fault detection, assume that there are 16 cables to be tested, and all 16 cables to be tested are connected with external pull-up resistors; First, it is detected whether there is a short circuit fault between the first cable and any one of the second to sixteenth cables: the CPU controls the CPLD to set the first cable to a low level. If the CPU reads through the CPLD that any one of the second to sixteenth cables is at a low level, it means that there is a short circuit fault between the first cable and the any one of the cables; if the CPU reads through the CPLD that any one of the second to sixteenth cables is at a high level, it means that there is no short circuit fault between the first cable and the any one of the cables; Then, it is detected whether there is a short circuit fault between the second cable and any one of the third to sixteenth cables: the CPU controls the CPLD to set the first cable to a high level, and the CPU controls the CPLD to set the second cable to a low level. If the CPU reads through the CPLD that any one of the third to sixteenth cables is at a low level, it means that there is a short circuit fault between the second cable and the any one of the cables; if the CPU reads through the CPLD that any one of the third to sixteenth cables is at a high level, it means that there is no short circuit fault between the second cable and the any one of the cables; Then, it is detected whether there is a short circuit fault between the third cable and any one of the fourth to sixteenth cables: the CPU controls the CPLD to set the first cable and the second cable to a high level, and the CPU controls the CPLD to set the third cable to a low level. If the CPU reads through the CPLD that any one of the fourth to sixteenth cables is at a low level, it means that there is a short circuit fault between the third cable and the any one of the cables; if the CPU reads through the CPLD that any one of the fourth to sixteenth cables is at a high level, it means that there is no short circuit fault between the third cable and the any one of the cables; Similarly, it is finally detected whether there is a short circuit fault between the 15th cable and the 16th cable: the CPU controls the CPLD to set the 1st cable to the 14th cable to a high level, and the CPU controls the CPLD to set the 15th cable to a low level. If the CPU reads the 16th cable as a low level through the CPLD, it means that there is a short circuit fault between the 15th cable and the 16th cable; if the CPU reads the 16th cable as a high level through the CPLD, it means that there is no short circuit fault between the 15th cable and the 16th cable.

6. A cable calibration and resistance measuring instrument for heavy-duty connectors according to claim 1, characterized in that: The heavy-duty connector dedicated cable calibration and resistance measuring instrument also includes a lithium battery pack, a soft keyboard, an LCD screen, a WIFI chip and a serial FLASH which are electrically connected to the CPU respectively. The lithium battery pack supplies power to the heavy-duty connector dedicated cable calibration and resistance measuring instrument, the soft keyboard is used to set test parameters, the WIFI chip is used to upgrade the test software, and the serial FLASH is used to save resistance test parameters and resistance correction coefficients.

7. A cable calibration and resistance measuring instrument for heavy-duty connectors according to claim 6, characterized in that: The lithium battery pack is a large-capacity lithium battery pack.

8. The heavy-duty connector dedicated cable calibration and resistance measuring instrument according to claim 6, characterized in that: The LCD screen is a large-screen LCD screen with a resolution of 480*320.

9. A cable calibration and resistance measuring instrument for heavy-duty connectors according to claim 6, characterized in that: The heavy-duty connector dedicated cable calibration and resistance measuring instrument further comprises a battery power detection module electrically connected to the CPU, and the battery power detection module is used to detect the power of the lithium battery pack.

10. The heavy-duty connector dedicated cable calibration and resistance measuring instrument according to claim 1, characterized in that: The heavy-duty connector dedicated cable calibration and resistance measuring instrument is a handheld structure.

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