Test device and method for identifying reliable connection of test cable

Abstract

A test device for identifying whether a test cable is reliably connected belongs to the field of signal measurement and comprises a test system and the test cable. The system is characterized by further comprising a connection sensing circuit. The connection sensing circuit is arranged on the tested product and is used for providing a detection signal for connecting the tested product and the test cable to the test system; the test system is provided with a special test circuit; the special test circuit comprises a processor, a memory and a test cable connection identification circuit; the test cable is provided with a cable address circuit and a sensing transmission line. The test cable connection identification circuit is used for identifying a cable address. A circuit connection relation is established among the test system, the test cable and the tested product; when the test system is electrified, whether the test cable is connected with one end of the test system and whether the other end of the test cable is connected with the tested product can be identified; testers are prompted to perform corresponding operation according to the identification result, and the reliable connection times of the connectors at the two ends of the test cable are memorized.

Description

Technical Field

[0001] The invention belongs to the field of signal measurement, and in particular relates to a test device and a test method for identifying whether a test cable is reliably connected. Background Art

[0002] When using test equipment to test products, test cables are often used. The test cable is connected to the test system at one end and the product under test at the other end through connectors at both ends. As a component of the test equipment, the test cable plays an important bridge role. Usually, the connectors used for connection at both ends have a pin structure at one end and a hole structure at the other end. The contact resistance between the pinholes is closely related to factors such as the contact area, contact pressure, and material between the pinholes. Therefore, the contact resistance between the pinholes changes significantly when there is a reliable connection and an unreliable connection.

[0003] However, in common test equipment, most test cables only have handwritten or paper label numbers, which cannot be associated with the test equipment through electrical signals and cannot be distinguished by the test system. At the same time, the test cables are not controlled by the test system and can be connected to the tested product at will when disconnected from the test system. Therefore, the test system does not know whether the connectors at both ends of the test cable are connected reliably or whether the number of uses has exceeded the limit. The test results often show that the test system misdetects and misjudges the status of the tested product. Summary of the invention

[0004] The present invention aims to solve the above-mentioned problem and provides a test device and method for identifying whether a test cable is reliably connected.

[0005] The test device for identifying whether a test cable is reliably connected according to the present invention comprises a test system and a test cable; and also comprises a connection sensing circuit; The connection sensing circuit is arranged on the product under test and is used to provide a detection signal of the connection between the product under test and the test cable to the test system; The test system is provided with a dedicated test circuit; The dedicated test circuit includes a processor, a memory and a test cable connection identification circuit; The test cable is provided with a cable address circuit and a sensing transmission line; Both ends of the test cable are provided with connectors, which are respectively a first connector for connecting the test cable to the test system and a second connector for connecting the test cable to the product under test; The aforementioned cable address circuit is arranged inside the first connector; The test cable connection identification circuit is used to identify the cable address. When performing the test, the test system is powered on first, and then the test system sends a control signal. According to the prompt of the test system, the test cable and the tested product are connected in sequence. Whether the connection status is reliable is given in real time by the test system.

[0006] Further, in the test device for identifying whether a test cable is reliably connected according to the present invention, the cable address circuit is implemented as follows: The first connector includes n pins as address identification pins; according to the principle of uniform distribution in physical space and centering the common address return terminal, one pin is selected as the common address return terminal, and the other pins are connected or disconnected with the pin (corresponding to 0 ohm and infinity); the relationship between different pins and the common address return terminal is encoded, and the address number of the corresponding test cable is from 1 to m. The address identification pins can also be randomly distributed. Each address identification pin is equivalent to a sampling point. In this scheme, a uniform distribution and centering of the common address return terminal are adopted. The more uniform the distribution, the more representative the test results are. The common address return terminal (as a common point) is centered, so that all address pins can be at the same physical distance from the test system, so that only one general judgment standard can be used to determine whether all address pins are reliably connected, otherwise each address pin needs to have its own judgment standard.

[0007] The number of address pins n on the first connector is determined according to the number of cables m required, and the relationship between the two is m = 2 n-1 – 1; In this formula, 1 can mean that the test cable is not connected or that there is no reliable connection. It is impossible to distinguish between the two during testing, so this situation needs to be removed.

[0008] Further, in the test device for identifying whether the test cable is reliably connected according to the present invention, when the cable address circuit tests the product under test, the number of address pins is n, the number of cables is m, and the number of connector pins required for normal functional performance testing of the product under test is q; when selecting the connector, it is necessary to add special test pins, then the number of pins of the second connector is q+u, and the number of pins of the first connector should be q+u+n; wherein u is not less than 2. The actual selection is based on the product size, and the larger the value of u, the more pins.

[0009] Furthermore, in the test device for identifying whether a test cable is reliably connected according to the present invention, both ends of the test cable are provided with locking mechanisms, which are respectively a first locking mechanism and a second locking mechanism; The first locking mechanism and the second locking mechanism are respectively arranged on the first connector and the second connector; The locking mechanism is provided with a movable block which can be displaced; the locking mechanism is controlled by the test system; The locking mechanism is in a locked state when it is disconnected from the test system; in the locked state, the movable block will extend out of the connector, and the extension length is greater than the mating depth L of the connector, making it impossible for the connector to be reliably connected.

[0010] Furthermore, in the test device for identifying whether a test cable is reliably connected according to the present invention, the locking mechanism comprises an outer shell; an opening is provided at the front end of the outer shell, and an electrical contact is provided at the rear end; The outer shell is provided with a permanent magnet and an armature which are fixedly connected in sequence; A moving block is arranged at the front end of the armature; the moving block passes through the aforementioned opening; The permanent magnet is provided with a spring; the armature is provided with a coil; The two ends of the coil are connected to the electrical contacts arranged at the rear end of the outer shell.

[0011] Furthermore, the testing method of the test device according to the present invention for identifying whether the test cable is reliably connected comprises: Step 1: Power on the test system and read the initial value of the number of connections of the connectors at both ends of the test cable; Step 2: The test system controls the moving block of the locking mechanism to enter a normal working state, so that the test cable is normally connected to the test system and the product under test, and an information prompt is given; Step 3: The test system starts the detection test cable connection identification circuit through a dedicated test circuit to determine whether the end of the test cable connected to the test system is reliably connected; if it does not meet the requirements, the judgment is repeated until the test result meets the reliable connection requirements; if it meets the requirements, the connection times are increased by 1 and stored; Step 4: The test system starts to detect the sensing transmission line of the test cable and the sensing connection line of the product under test through a dedicated test circuit to determine whether the end of the test cable connected to the product under test is reliably connected; if it does not meet the requirements, the test is repeated until the test result meets the reliable connection requirements; if it meets the requirements, the number of connections is increased by 1 and stored; Step 5: Start testing the product under test.

[0012] Furthermore, the test method for identifying whether a test cable is reliably connected and the method for judging whether the test cable is reliably connected to a test system and a product under test include: accurately measuring in advance the contact resistance R1 when the test cable is reliably connected to the test equipment and the contact resistance R2 when the test cable is reliably connected to the product under test, and using these two values ​​as measurement standards; comparing each test result with R1 and R2, and if the error is within the allowable range, it is considered to be a reliable connection, otherwise the connection is unreliable.

[0013] The test device and method for identifying whether a test cable is reliably connected according to the present invention have the following technical effects: 1) Each test cable has a unique hardware address. Different test cables have different addresses, which can be recognized and memorized by the test system. The connector pins are numbered, which can be recognized by the hardware circuit and then memorized by the test equipment; 2) The method of measuring whether the on-resistance value is within the range is used to identify whether the test cable is reliably connected. It does not affect the product under test, nor is it affected by the product under test. 3) The test system has the function of controlling whether the test cable is available; when the test system powers on the test cable and cancels the anti-connection function of the locking mechanism, the test cable can be used normally; when the test cable leaves the test system and the anti-connection function of the locking mechanism takes effect, the test cable cannot be used normally; 4) A circuit connection is established between the test system, the test cable and the product under test. When the test system is powered on, it can identify whether one end of the test cable is connected to the test system and the other end is connected to the product under test. The tester is prompted to perform corresponding operations based on the identification result, and the number of reliable connections of the connectors at both ends of the test cable is memorized. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A schematic block diagram of the structure of a test device for identifying whether a test cable is reliably connected according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the principle of a dedicated test circuit for a test system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the cable address circuit principle according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the position distribution of the address circuit pins according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the locking mechanism structure according to an embodiment of the present invention; Among them, 1-shell, 2-permanent magnet, 3-armature, 4-spring, 5-coil, 6-moving block. DETAILED DESCRIPTION

[0015] The following describes in detail the test device and method for identifying whether a test cable is reliably connected according to the present invention through the accompanying drawings and embodiments.

[0016] This embodiment discloses a test device for identifying whether a test cable is reliably connected. Figure 1As shown, it includes a test system and a test cable; the test system host needs to have a display interface and an IO expansion interface. The display interface is used to display test information, and the IO expansion interface is used to connect the test cable and the product under test. For example, if you use the IPC-710 industrial computer of EVOC, the VGA interface is connected to the display, and the expansion interface is connected to the test cable and the dedicated test pin of the product under test. It also includes a connection sensing circuit. In the embodiment of the present disclosure, the connection sensing circuit is composed of Figure 3 The pull-up resistors R1, R2, R3, R4 and R5, as well as VCC and GND shown in FIG. 1 are provided; the connection sensing circuit is arranged on the product under test, and is used to provide the test system with a detection signal of the connection between the product under test and the test cable; Figure 2 As shown, the test system is provided with a dedicated test circuit; the dedicated test circuit includes a processor, a memory and a test cable connection identification circuit; wherein the processor and the memory are shared by the test system; the test cable is provided with a cable address circuit and a sensing transmission line; both ends of the test cable are provided with connectors, namely a first connector connecting the test cable to the test system and a second connector connecting the test cable to the product under test; the aforementioned cable address circuit is arranged inside the first connector; the test cable connection identification circuit is used to identify the cable address.

[0017] The cable address circuit is implemented as follows: the first connector includes n pins as address identification pins; according to the principle of uniform distribution in physical space and the centralization of the common address return line, one pin is selected as the common address return line (as a common point), and the other pins are connected or disconnected with the pin (corresponding resistance values ​​are 0 ohms and infinity); the relationship between different pins and the common address return line is encoded, and the corresponding test cable address number is from 1 to m. Figure 4 The pins shown in the figure are evenly distributed, and the pins A1, A2, and An are approximately at the three vertices of an equilateral triangle, surrounding a common point G, which is at the center of the equilateral triangle. The number n of address pins on the first connector is determined according to the number m of cables required, and the relationship between the two is m = 2 n-1 – 1; In this formula, 1 can mean that the test cable is not connected or that there is no reliable connection. It is impossible to distinguish between the two during testing, so this situation needs to be removed.

[0018] In the disclosed embodiment, both ends of the test cable are provided with locking mechanisms, namely a first locking mechanism and a second locking mechanism; the first locking mechanism and the second locking mechanism are respectively arranged on the aforementioned first connector and the second connector; the locking mechanism is provided with a movable block 6 that can be displaced.

[0019] In the embodiment of the present disclosure, the number of test cables is determined based on the test device disclosed above for identifying whether the test cables are reliably connected. If the number of test cables m required is 7, according to the formula m = 2 n-1 – 1, then the address pins n required are 4; the address pins of the product under test are 2.

[0020] Then determine the pins of the connectors at both ends of the test cable; in the disclosed embodiment, the test system requires 30 pins to complete normal functional performance testing, 5 test cables are required, and there are 2 dedicated test pins on the product under test. Based on this calculation, the connector connecting the test cable to the test system requires 30+3 pins, of which 3 pins are dedicated test pins, which are also hardware address pins. The end connected to the product under test requires 30+3+2 pins, of which 2 pins are dedicated test pins, because the dedicated test pins of the product under test are connected from the test system through the test cable, so they need to be added together.

[0021] Table 1 After determining the number of pins on the connectors at both ends of the test cable, as shown in Table 1, select the connector specifications based on this, and also determine the corresponding connector specifications installed on the test system and the product under test.

[0022] According to the number of address pins, in accordance with the principle of uniform distribution and common location in the center, in the embodiment of the present disclosure, pins 1, 15 and 30 are located at both ends and in the middle, respectively, and are therefore selected as address pins, and the corresponding test cable hardware address numbers are from 1 to 5. On the tested product, for example, if the dedicated test pin numbers are 1 and 30, the pins corresponding to one end of the test system may be 2 and 28. In this embodiment, according to the common arrangement habits of connectors, 1 and 2, 28 and 30 are arranged together and located at both ends of the connector. This selection of test pins complies with the principle of uniform distribution and is not crowded.

[0023] Both locking mechanisms are controlled by the test system and use the same +5V power supply. In the disclosed embodiment, the locking mechanism adopts the electromagnetic working principle; Figure 5As shown, it includes an outer shell 1; an opening is provided at the front end of the outer shell 1, and an electric contact is provided at the rear end; a permanent magnet 2 and an armature 3 are provided in the outer shell 1, which are fixedly connected in sequence; a movable block 6 is provided at the front end of the armature 3; the movable block 6 passes through the aforementioned opening; a spring 4 is sleeved on the permanent magnet 2; a coil 5 is sleeved on the armature 3; both ends of the coil 5 are connected to the electric contact provided at the rear end of the aforementioned outer shell 1. The locking mechanism is controlled by the test system; the locking mechanism is in a locked state when it is disconnected from the test system; in the locked state, the aforementioned movable block 6 will extend out of the connector, and the extension length is greater than the mating depth L of the connector, so that the connector cannot be reliably connected.

[0024] The locking mechanism is located on the connector at one end of the test system. The mating depth of the connector is Lp. The length of the extended part of the locking mechanism is La=Lp+2, and the margin is 2mm. The test system provides a +5V working power supply for control. When the test system energizes the coil 5 with +5V, the coil 5 generates a magnetic field, which generates a magnetic force to squeeze the spring 4, and the piston drives the movable block 6 to retract into the locking mechanism. At this time, the test cable socket and plug can be connected normally; when the test cable is not connected to the test system, the coil 5 is powered off, the magnetic field disappears, the spring 4 is no longer squeezed, and returns to a free state, and the piston drives the movable block 6 to extend out of the locking mechanism. At this time, the test cable socket and plug are blocked by the movable block 6 and cannot be connected.

[0025] After the connection is completed, start the test system to test the contact resistance R.

[0026] In the disclosed embodiment, the standard contact resistance value R corresponding to the reliable connection calibrated in advance is 7mΩ, the error is 10%, and the corresponding resistance value is ±0.7mΩ, which is stored in the test system. The test value is compared with the standard value. If the error is within the range, the prompt message "the test cable and the tested product have been reliably connected" is output. Otherwise, the prompt "the test cable and the tested product are not reliably connected" is output, and the judgment is repeated until a reliable connection is achieved.

[0027] If the connection is reliable, then the total number of connections S and the number of reliable connections S of the test cable are m Add 1 respectively (S=S+1, S m =S m +1), and information is memorized and outputted. Otherwise, only the total number of connections is increased by 1 (S=S+1). If the number of reliable connections has reached the life of the connector, which is 500 times, a prompt is given that the number of connections has reached the maximum allowed number.

[0028] The test equipment and method for identifying whether a test cable is reliably connected described in this embodiment can accurately identify whether the connectors at both ends of the test cable are reliably connected to the test system and the product under test, prevent the test cable from being connected out of the control of the test system and memorize the number of reliably connected times of the connectors at both ends of the test cable to the test system and the product under test.

Claims

1. A test device for identifying whether a test cable is reliably connected, comprising a test system and a test cable; characterized in that: Also included is a connection sensing circuit; The connection sensing circuit is arranged on the product under test and is used to provide a detection signal of the connection between the product under test and the test cable to the test system; The test system is provided with a dedicated test circuit; The dedicated test circuit includes a processor, a memory and a test cable connection identification circuit; The test cable is provided with a cable address circuit and a sensing transmission line; Both ends of the test cable are provided with connectors, which are respectively a first connector for connecting the test cable to the test system and a second connector for connecting the test cable to the product under test; The aforementioned cable address circuit is arranged inside the first connector; The test cable connection identification circuit is used to identify the cable address.

2. The test device for identifying whether a test cable is reliably connected according to claim 1, characterized in that: The cable address circuit is implemented as follows: The first connector includes n number of pins as address identification pins; one pin is selected from the pins as a common address return line end, and the other pins are connected or disconnected with the pin; the relationship between different pins and the common address return line end is encoded, and the address number of the corresponding test cable is from 1 to m; The number of address pins n on the first connector is determined according to the number of cables m required, and the relationship between the two is m = 2 n-1 – 1.

3. The test device for identifying whether a test cable is reliably connected according to claim 2, characterized in that: When the cable address circuit tests the product under test, the number of address pins is n, the number of cables is m, and the number of connector pins required for normal functional performance testing of the product under test is q; when selecting the connector, it is necessary to add special test pins, then the number of pins of the second connector is q+u, and the number of pins of the first connector should be q+u+n; Where u is not less than 2.

4. The test device for identifying whether a test cable is reliably connected according to claim 1, 2 or 3, characterized in that: Both ends of the test cable are provided with locking mechanisms, which are a first locking mechanism and a second locking mechanism respectively; The first locking mechanism and the second locking mechanism are respectively arranged on the first connector and the second connector; The locking mechanism is provided with a movable block which can be displaced; the locking mechanism is controlled by the test system; The locking mechanism is in a locked state when it is disconnected from the test system; In the locked state, the movable block will extend out of the connector, and the extension length is greater than the mating depth L of the connector, so that the connector cannot be reliably connected.

5. The test device for identifying whether a test cable is reliably connected according to claim 4, characterized in that: The locking mechanism comprises an outer shell; an opening is arranged at the front end of the outer shell, and an electrical contact is arranged at the rear end; The outer shell is provided with a permanent magnet and an armature which are fixedly connected in sequence; A moving block is arranged at the front end of the armature; the moving block passes through the aforementioned opening; The permanent magnet is provided with a spring; the armature is provided with a coil; The two ends of the coil are connected to the electrical contacts arranged at the rear end of the outer shell.

6. A method for testing a test device for identifying whether a test cable is reliably connected according to claim 5, characterized in that include: Step 1: Power on the test system and read the initial value of the number of connections of the connectors at both ends of the test cable; Step 2: The test system controls the moving block of the locking mechanism to enter a normal working state, so that the test cable is normally connected to the test system and the product under test, and an information prompt is given; Step 3: The test system starts the detection test cable connection identification circuit through a dedicated test circuit to determine whether the end of the test cable connected to the test system is reliably connected; If it does not meet the requirements, the test is repeated until the test result meets the reliable connection requirements; if it meets the requirements, the connection times are increased by 1 and stored; Step 4: The test system starts to detect the sensing transmission line of the test cable and the sensing connection line of the product under test through a dedicated test circuit to determine whether the end of the test cable connected to the product under test is reliably connected; If it does not meet the requirements, the test is repeated until the test result meets the reliable connection requirements; if it meets the requirements, the connection times are increased by 1 and stored; Step 5: Start testing the product under test.

7. The test method for identifying whether a test cable is reliably connected according to claim 6, characterized in that: The method for judging whether the connection between the test cable, the test system and the product under test is reliable includes: accurately measuring in advance the contact resistance R1 when the test cable is reliably connected to the test equipment, and the contact resistance R2 when the test cable is reliably connected to the product under test, and using these two values ​​as measurement standards; comparing each test result with R1 and R2, and if the error is within the allowable range, it is considered to be a reliable connection, otherwise the connection is unreliable.

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