A cascade automatic tester

Abstract

The invention relates to a cascade automatic tester, wherein a test host and slave test units and the slave test units are cascaded through bus cables to form a main test system network; the slave test unit and the tested point of the tested object are connected through a transfer cable; the insulation withstand voltage test unit is connected to the test host through a serial port line and is connected to the slave test unit through an analog signal line; the relay drive unit is connected to the test host through the bus cable; the test host converts an external input network table into a corresponding test instruction and forwards it to the slave test unit, and when the test instruction is a relay test, it is forwarded to the relay drive unit at the same time; the slave test unit receives the test instruction and parses it, and connects the corresponding tested point on the tested object to the test host or the insulation withstand voltage test unit according to the parsed content; the relay drive unit parses the received test instruction and applies excitation to the coil of the tested relay according to the parsed content.

Description

Technical Field

[0001] The invention relates to the field of automatic testing, in particular to a cascade type automatic testing instrument. Background Art

[0002] With the development of modern measurement and control technology, various electrical and electronic networks and various bus technologies are increasing, and the scale and complexity of the system are also expanding, which makes the testing of electronic equipment and cable networks more difficult. Traditional manual testing is inefficient and unreliable, while the existing automatic testers on the market have problems such as limited test scale and incomplete functional coverage. Summary of the invention

[0003] The technical problem solved by the present invention is: in order to overcome the shortcomings of the prior art, the present invention provides a cascade automatic tester, which has good versatility and scalability, a large test scale, and test functions covering insulation withstand voltage test, path test, open circuit test, component test (resistance, relay, etc.) and other contents, and can meet the testing needs of most electronic equipment and cable networks.

[0004] The technical solution of the present invention is: a cascade automatic tester, comprising a test host, a slave test unit, an insulation withstand voltage test unit, and a relay drive unit;

[0005] The test host and the slave test units and the slave test units are cascaded through bus cables to form a main test system network; the slave test unit and the test point of the object under test are connected through a transfer cable; the insulation withstand voltage test unit is connected to the test host through a serial port line and connected to the slave test unit through an analog signal line; the relay drive unit is connected to the test host through a bus cable;

[0006] The test host converts the external input network table into corresponding test instructions and forwards it to the slave test unit. When the above test instructions are for relay tests, they are also forwarded to the relay drive unit; the slave test unit receives the above test instructions and parses them, and connects the corresponding test points on the object under test to the test host or the insulation withstand voltage test unit according to the parsed content; the relay drive unit parses the received test instructions and excites the coil of the relay under test according to the parsed content; the test host performs tests according to the test instructions and reads the measurement results; when the insulation withstand voltage test is performed, the test host controls the insulation withstand voltage test unit to output voltage to start the test, and the insulation withstand voltage test unit returns the measurement results to the test host.

[0007] Furthermore, the slave test unit includes a base plate, a function expansion board, and a plurality of gate boards; the base plate is used to insert the function expansion board and the gate board, and is used to realize signal connectivity between the boards in the slave test unit;

[0008] The function expansion board receives and parses the test instructions from the test host, and forwards the parsed content to the selection board, which selects the relevant test points on the object to be connected according to the instruction content; the function expansion board connects the selection board to the insulation withstand voltage test unit when performing the insulation withstand voltage test, and connects the selection board to the test host when performing other tests.

[0009] Furthermore, the function expansion board includes a control module, a function selection module, and a bus driver for communicating with the test host and the gate board; the control module is used to receive the test instructions from the test host, parse them, and forward them to the gate board; the function selection module connects the gate board to the insulation withstand voltage test unit during the insulation withstand voltage test, and connects the gate board to the test host during other tests; wherein

[0010] The function selection module has four test signal ports denoted as A, B, C, and D and six function switching ports denoted as A1, B1, A2, B2, C2, and D2;

[0011] The A, B, C, and D ports are connected to each selection board through the base plate; A1 and B1 are respectively connected to the positive output and negative output terminals of the insulation withstand voltage test unit; the A1 port is connected to the A and B ports through relays K1A and K1B respectively; the B1 port is connected to the C and D ports through relays K1C and K1D respectively; the A2 port is connected to the A and B ports through relays K2A and K2B respectively; the C2 port is connected to the C and D ports through relays K2C and K2D respectively; the B2 and D2 ports are connected to the B and D ports through relays K2E and K2F respectively; A2, B2, C2, and D2 are connected to the test host.

[0012] Furthermore, by controlling the A2, B2, C2, and D2 port relays, a 4-wire system or a 2-wire system is selected for low-voltage resistance testing.

[0013] Furthermore, the relay driving unit includes a base plate, a function expansion board, and multiple relay driving boards; the base plate is used to insert the function expansion board and the relay driving board, and is used to realize signal connectivity between the boards in the relay driving unit; the function expansion board receives and parses the test instructions from the test host, and forwards the parsed content to the relay driving board, which excites the coil of the relay under test.

[0014] Furthermore, the relay driver board includes a control module, a bus driver for realizing communication with the function expansion board, and a relay array;

[0015] The control module selects the corresponding relay array to realize the output voltage of the corresponding excitation according to the power supply requirements of the relay under test in the analysis content; the relay array is composed of multiple groups of relays, each group of relays includes multiple relays, one end of each relay switch is connected to a relay driving voltage of a specification, and the other end of the switch is connected to the total output terminals CH1+ and CH1G; the output terminals CH1+ and CH1G of each group of relays are respectively connected to the two ends of the coil of the relay under test.

[0016] Furthermore, the test host compares the current test instruction with the next test instruction when sending the test instruction, and requires in the instruction that the same relay that needs to be closed in both tests maintains the same state.

[0017] Furthermore, the control module records the number of times each relay is used. Each time the relay is closed, the number of times the relay is used is updated. At the same time, the relay number and the number of times used are stored, and a reminder is given when the relay reaches the end of its life and needs to be replaced.

[0018] Furthermore, the test host automatically runs a test self-learning module to obtain the complete connection status of the object under test, that is, the network table; the test self-learning module includes a setting module, a fast scanning test module, and a self-learning analysis module;

[0019] The setting module is used to set the starting range of the tested points or the number of tested points n for the tested object to be connected to the tester, as well as the judgment criteria for the connection relationship of the tested object;

[0020] The fast scanning test module quickly implements the test between all the test points according to the principle of reducing repeated tests, and records the resistance values ​​between the test points in the temporary loop table with the test point numbers as marks;

[0021] The self-learning analysis module determines the complete connection status of the measured object according to the resistance value recorded in the temporary loop table and the judgment standard of the connection relationship of the measured object set in the setting module.

[0022] Furthermore, the fast scanning test module is implemented in the following manner:

[0023] Step 1: Sequentially number the test points and set up a temporary loop table, which records the resistance between the test points in the form of an n*n matrix. When the test current is in the forward direction, the resistance value of point i to point j is recorded in matrix a. ij Position, when the test current is reversed, the resistance value of point i to point j is recorded in matrix a ji Location;

[0024] Step 2: Starting from the first measured point marked as point 1, scan and test other points one by one, obtain the resistance relationship between point 1 and all other points and record it in the temporary loop table, and obtain the set V1 of points that are connected to point 1 according to the judgment standard of the connection relationship of the measured object;

[0025] Step 3: Let the set of all points that are not connected to point 1 be U1=U-V1, select any point in U1 and record it as point a, scan and test other points in U1 point by point, get the resistance relationship between point a and all other points and record it in the temporary loop table, and get the set of points that are connected to point a, V2;

[0026] Step 4: The set of points that are not conductive with point 1 is recorded as U2 = U1-V2, and any point in U2 except point a is recorded as point b. Scan and test other points in U2 point by point, obtain the resistance relationship between point b and all other points and record it in the temporary loop table, and obtain the set of points that are conductive with point b, V3;

[0027] Step 5: The set of points that are not connected to point 1 is recorded as U3=U2-V3, and any point in U2 except points a and b is recorded as point c. Scan and test other points in U3 point by point, and obtain the resistance relationship between point c and all other points and record it in the temporary loop table, and obtain the set of points that are connected to point c, V4;

[0028] Step 6: And so on, until the set U of points that are not connected to point 1 m is an empty set;

[0029] Step 7: Reverse the test current and repeat steps 2 to 6.

[0030] The beneficial effects of the present invention compared with the prior art are:

[0031] (1) The overall architecture of the present invention adopts a multi-level cascade mode, which has strong scalability and the maximum test scale can reach more than 100,000 points;

[0032] (2) The present invention integrates multiple functions such as path test, circuit break test, insulation withstand voltage test, component test, etc., and can meet the testing requirements of most electronic equipment and cable networks;

[0033] (3) The relay driver board in the present invention can automatically switch between three driving voltages: 5V, 12V, and 28V, and can adapt to the situation where relays with different power supply voltages are tested in the same object under test. The voltage range provided covers the common relay power supply voltages.

[0034] (4) The present invention can realize the functions of relay life protection and monitoring, thereby extending the service life of the entire instrument and providing reminders when accessories need to be replaced, thereby ensuring the normal operation of the entire instrument.

[0035] (5) The present invention adopts a modular design and can be combined or cut according to actual test tasks, which can greatly reduce maintenance and use costs.

[0036] (6) When changing to a different type of measured object, it is only necessary to replace the adapter cable, which is highly versatile. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of a cascade automatic tester of the present invention;

[0038] Figure 2 A schematic diagram of the connection of the test signal line between the expansion board and the gate board of the present invention;

[0039] Figure 3 It is a schematic diagram of the function expansion board of the present invention;

[0040] Figure 4 It is a schematic diagram of the relay driving board of the present invention. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the embodiments.

[0042] like Figure 1 As shown, a cascade automatic tester includes a test host, a slave test unit, an insulation withstand voltage test unit, a relay drive unit, a bus cable, a transfer cable and other components; the test host and the slave test unit and the slave test units are cascaded through the bus cable to form a main test system network; the slave test unit and the object to be tested are connected through the transfer cable; the insulation withstand voltage test unit is connected to the test host through a serial port line and is connected to the slave test unit through an analog signal line; the relay drive unit is connected to the test host through the bus cable.

[0043] The bus cable contains 6 signal lines, including 2 28V power lines, 2 fieldbus communication lines, and 4 analog signal control lines. The fieldbus communication line uses a twisted pair shielded line to reduce environmental interference.

[0044] The communication between the above-mentioned test host and the slave test unit and relay drive unit is carried out through the field bus, and the communication rate can reach 1Mbps. The test host is composed of a controller, a measurement module, and a field bus module. The controller is responsible for the timing control of the entire test process and sends a test command frame to each slave unit (also called a slave) on the field bus. Each command frame has 8 bytes, including function selection, slave number, test point number and other information. The measurement module is responsible for the execution of the test task, and the field bus module is responsible for the communication between the test host and each slave unit on the bus. The selected slave unit connects the specified test point to the test channel and cooperates with the test host to complete the selected test function item.

[0045] The slave test unit as described above is composed of 1 baseboard, 1 function expansion board, and 16 gate boards (the number of gate boards is determined by the baseboard specifications and the gate board specifications). The inter-board communication within the slave test unit is carried out using a half-duplex serial bus, and the function expansion board sends the parsed test command to each slave on the half-duplex serial bus. The baseboard is used to insert the function expansion board and the gate board, as well as the signal connection between the boards in this unit. The function expansion board is responsible for receiving, parsing and forwarding the test instructions from the test host, and switching functions according to the commands. The gate board selects the test point on the object to be tested that needs to be connected according to the instructions. Each gate board can support 64 test points, and each slave test unit can support 1024 test points.

[0046] The above-mentioned base plate uses Shengyi S1000-2 board to improve reliability.

[0047] like Figure 2 As shown, the test signal lines sigA, sigB, sigC, and sigD between the expansion board and the gate board are connected through the motherboard. As described above, up to 110 slave test units can be cascaded. (Determined by the number of nodes supported by the selected bus transceiver)

[0048] The function expansion board is composed of a power module, a control module, a field bus driver, a half-duplex serial bus driver, and a function selection module. The control module is composed of a 32-bit ARM chip and peripheral circuits, and the function selection module is composed of a relay array.

[0049] like Figure 3As shown, the function selection module can select insulation withstand voltage and low voltage resistance test according to the test requirements, and the low voltage resistance test can select 4-wire or 2-wire test. A1 and B1 are respectively connected to the positive output terminal (Pos) and negative output terminal (Neg) of the insulation withstand voltage test unit, A2, B2, C2, and D2 are respectively connected to the measurement module in the test host, and A, B, C, and D are connected to each selection board through the bottom plate. If an insulation withstand voltage test needs to be performed, the ARM chip controls relays K1A and K1C to close, so as to form an insulation withstand voltage measurement loop, and then the insulation withstand voltage test unit measures the resistance between points A and C, and then returns the test result to the test host, that is, completing an insulation withstand voltage test; if a 2-wire test related to low-voltage resistance needs to be performed, the ARM chip controls relays K2A and K2C to close, and then the test host measures the resistance between points A and C, that is, completing a 2-wire low-voltage resistance test; similarly, if a 4-wire test related to measuring low-voltage resistance is required, the ARM chip controls relays K2B, K2D, K2E, and K2F to close, at which time A2 and B2 are connected to the same end of the object under test, and C2 and D2 are connected to the other end of the object under test, A2 and C2 are used to apply excitation to the object under test, and B2 and D2 are used to form the measurement points in the measurement loop, and then the test host measures the resistance between points B and D, that is, completing a 4-wire low-voltage resistance test.

[0050] The insulation withstand voltage test unit as described above is enabled when the insulation withstand voltage test function is selected. The test host can program it to output AC voltage (up to 5kV) or DC voltage (up to 6kV). The voltage is applied to the two points where the object under test is connected to the tester through a signal cable. The insulation withstand voltage test unit measures the impedance value at this time and then returns the test result to the test host to complete an insulation withstand voltage test.

[0051] The relay drive unit described above is composed of 1 base plate, 1 function expansion board, and 8 relay drive boards (the number of relay drive boards is determined by the base plate specifications and relay drive board specifications). The base plate is used to insert the function expansion board and the relay drive board, and the signals between the boards in the relay drive unit are interconnected. The function expansion board receives and parses the test instructions from the test host, and forwards the parsed content to the relay drive board, which applies excitation to the coil of the relay under test. Each relay drive unit can apply excitation to 320 relays.

[0052] The relay driver board is composed of a power module, a control module, a half-duplex serial bus driver, and a relay array. The relay driver board can support the driving of three voltage specifications of 5V, 12V, and 28V relays, and can automatically switch under the control of the control module.

[0053] like Figure 4As shown, there are 40 groups of relay arrays shown in the figure on the driver board. Taking one group of relays as an example, CH1+ and CH1G are respectively connected to the two ends of the relay coil under test, which are used to apply excitation to the relay under test; Out1A, Out1B, and Out1C are the relay control ends on the board; the control chip controls the closed relay required for this test according to the test requirements. If a 5V voltage needs to be added to the relay coil under test, the control chip controls the Out1B signal to close the K01B relay to achieve this; if a 12V voltage needs to be added to the relay coil under test, the control chip controls the Out1C signal to close the K01C relay to achieve this; if a 28V voltage needs to be added to the relay coil under test, the control chip controls the Out1A signal to close the K01C relay to achieve this.

[0054] All functional modules using relays in the present invention have the functions of relay life protection and monitoring. For functional modules containing relays, the relays to be switched are selected by the test host to avoid repeated closing and disconnecting of the same relay, so as to reduce the waste of relay life and achieve the purpose of life protection. For example, the first test requires closing relays 2 and 5, and the second test requires closing relays 2 and 11. After the first test, only relay 5 is disconnected and relay 11 is closed, and no operation is performed on relay 2. At the same time, the control module records the number of times each relay on the board is used. Each time the relay is closed, the number of times the relay is used is updated. At the same time, the relay number and the number of times used are stored in the E2PROM chip, and the user is reminded when the relay reaches the end of its life and needs to be replaced. At the same time, the relay life usage can also be checked at any time.

[0055] The test host in the present invention can automatically run the test self-learning module to obtain the complete connection status of the object under test, that is, the network table; the test self-learning module includes a setting module, a fast scanning test module, and a self-learning analysis module;

[0056] The setting module is used to set the starting range of the tested points or the number of tested points n for the tested object to be connected to the tester, as well as the judgment criteria for the connection relationship of the tested object;

[0057] The fast scanning test module quickly implements the test between all the test points according to the principle of reducing repeated tests, and records the resistance values ​​between the test points in the temporary loop table with the test point numbers as marks;

[0058] The self-learning analysis module determines the complete connection status of the measured object according to the resistance value recorded in the temporary loop table and the judgment standard of the connection relationship of the measured object set in the setting module.

[0059] The fast scan test module is implemented in the following way:

[0060] Step 1: Sequentially number the test points and set up a temporary loop table, which records the resistance between the test points in the form of an n*n matrix. When the test current is in the forward direction, the resistance value of point i to point j is recorded in matrix a. ij Position, when the test current is reversed, the resistance value of point i to point j is recorded in matrix a ji Location;

[0061] Step 2: Starting from the first measured point marked as point 1, scan and test other points one by one, obtain the resistance relationship between point 1 and all other points and record it in the temporary loop table, and obtain the set V1 of points that are connected to point 1 according to the judgment standard of the connection relationship of the measured object;

[0062] Step 3: Let the set of all points that are not connected to point 1 be U1=U-V1, select any point in U1 and record it as point a, scan and test other points in U1 point by point, get the resistance relationship between point a and all other points and record it in the temporary loop table, and get the set of points that are connected to point a, V2;

[0063] Step 4: The set of points that are not conductive with point 1 is recorded as U2 = U1-V2, and any point in U2 except point a is recorded as point b. Scan and test other points in U2 point by point, obtain the resistance relationship between point b and all other points and record it in the temporary loop table, and obtain the set of points that are conductive with point b, V3;

[0064] Step 5: The set of points that are not connected to point 1 is recorded as U3=U2-V3, and any point in U2 except points a and b is recorded as point c. Scan and test other points in U3 point by point, and obtain the resistance relationship between point c and all other points and record it in the temporary loop table, and obtain the set of points that are connected to point c, V4;

[0065] Step 6: And so on, until the set U of points that are not connected to point 1 m is an empty set;

[0066] Step 7: Reverse the test current and repeat steps 2 to 6.

[0067] By adopting the cascade mode of the present invention, each functional unit can be placed in the same cabinet to form a cabinet-type tester; or each functional unit can be placed on different wheeled mobile racks and dispersed at the test site to form a distributed tester.

[0068] The cascade automatic tester provided by the present invention has good versatility and scalability. The maximum test scale can reach more than 100,000 points. The test functions cover multiple contents such as path test, open circuit test, insulation withstand voltage test, relay test, etc., which can meet the test requirements of most electronic equipment and cable networks. It adopts a modular design, which can greatly reduce maintenance and use costs.

[0069] Parts of the present invention that are not described in detail belong to common knowledge among those skilled in the art.

Claims

1. A cascade automatic tester, characterized in that Including test host, slave test unit, insulation withstand voltage test unit, relay drive unit; The test host and the slave test units and the slave test units are cascaded through bus cables to form a main test system network; the slave test unit and the test point of the object under test are connected through a transfer cable; The insulation withstand voltage test unit is connected to the test host through a serial port line and connected to the slave test unit through an analog signal line; the relay drive unit is connected to the test host through a bus cable; The test host converts the external input network table into a corresponding test instruction and forwards it to the slave test unit. When the test instruction is a relay test, it is also forwarded to the relay drive unit. The test unit receives the above test instructions and parses them, and connects the corresponding test point on the tested object to the test host or the insulation withstand voltage test unit according to the parsed content; the relay drive unit parses the received test instructions and applies excitation to the coil of the tested relay according to the parsed content; the test host performs the test according to the test instructions and reads the measurement results; when the insulation withstand voltage test is performed, the test host controls the insulation withstand voltage test unit to output the voltage to start the test, and the insulation withstand voltage test unit returns the measurement results to the test host; The test host automatically runs a test self-learning module to obtain the complete connection status of the object under test, that is, the network table; the test self-learning module includes a setting module, a fast scanning test module, and a self-learning analysis module; The setting module is used to set the starting range of the tested points or the number of tested points n for the tested object to be connected to the tester, as well as the judgment criteria for the connection relationship of the tested object; The fast scanning test module quickly implements the test between all the test points according to the principle of reducing repeated tests, and records the resistance values ​​between the test points in the temporary loop table with the test point numbers as marks; The self-learning analysis module determines the complete connection status of the object under test according to the resistance value recorded in the temporary loop table and the judgment standard of the connection relationship of the object under test set in the setting module; The fast scan test module is implemented in the following way: Step 1: Sequentially number the test points and set up a temporary loop table, which records the resistance between the test points in the form of an n*n matrix. When the test current is in the forward direction, the resistance value of point i to point j is recorded in matrix a. ij Position, when the test current is reversed, the resistance value of point i to point j is recorded in matrix a ji Location; Step 2: Starting from the first measured point marked as point 1, scan and test other points one by one, obtain the resistance relationship between point 1 and all other points and record it in the temporary loop table, and obtain the set V1 of points that are connected to point 1 according to the judgment standard of the connection relationship of the measured object; Step 3: Let the set of all points that are not connected to point 1 be U1=U-V1, select any point in U1 and record it as point a, scan and test other points in U1 point by point, get the resistance relationship between point a and all other points and record it in the temporary loop table, and get the set of points that are connected to point a, V2; Step 4: The set of points that are not conductive with point 1 is recorded as U2 = U1-V2, and any point in U2 except point a is recorded as point b. Scan and test other points in U2 point by point, obtain the resistance relationship between point b and all other points and record it in the temporary loop table, and obtain the set of points that are conductive with point b, V3; Step 5: The set of points that are not connected to point 1 is recorded as U3=U2-V3, and any point in U2 except points a and b is recorded as point c. Scan and test other points in U3 point by point, and obtain the resistance relationship between point c and all other points and record it in the temporary loop table, and obtain the set of points that are connected to point c, V4; Step 6: And so on, until the set U of points that are not connected to point 1 m is an empty set; Step 7: Reverse the test current and repeat steps 2 to 6.

2. The tester according to claim 1, characterized in that: The slave test unit includes a base plate, a function expansion board, and a plurality of gate boards; the base plate is used to insert the function expansion board and the gate board, and is used to realize signal connectivity between the boards in the slave test unit; The function expansion board receives and parses the test instructions from the test host, and forwards the parsed content to the selection board, which selects the relevant test points on the tested object to be connected according to the instruction content; According to the parsed content, the function expansion board connects the selection board to the insulation withstand voltage test unit when performing the insulation withstand voltage test, and connects the selection board to the test host when performing other tests.

3. The tester according to claim 2, characterized in that: The function expansion board includes a control module, a function selection module, and a bus driver for communicating with the test host and the gate board; the control module is used to receive the test instructions from the test host, parse them, and forward them to the gate board; the function selection module connects the gate board to the insulation withstand voltage test unit during the insulation withstand voltage test, and connects the gate board to the test host during other tests; in The function selection module has four test signal ports denoted as A, B, C, and D and six function switching ports denoted as A1, B1, A2, B2, C2, and D2; The A, B, C, and D ports are connected to each selection board through the bottom plate; A1 and B1 are respectively connected to the positive output and negative output terminals of the insulation withstand voltage test unit; the A1 port is connected to the A and B ports through relays K1A and K1 B respectively; the B1 port is connected to the C and D ports through relays K1C and K1 D respectively; the A2 port is connected to the A and B ports through relays K2A and K2B respectively; the C2 port is connected to the C and D ports through relays K2C and K2D respectively; the B2 and D2 ports are connected to the B and D ports through relays K2E and K2F respectively; A2, B2, C2, and D2 are connected to the test host.

4. The tester according to claim 3, characterized in that: Through the control of the A2, B2, C2, and D2 port relays, select the 4-wire or 2-wire system for low-voltage resistance testing.

5. The tester according to claim 1 or 3, characterized in that: The relay drive unit comprises a base plate, a function expansion board, and a plurality of relay drive boards; the base plate is used for inserting the function expansion board and the relay drive board, and is used for realizing signal connectivity between the boards in the relay drive unit; the function expansion board receives and parses the test instructions from the test host, and forwards the parsed contents to the relay drive board, which excites the coil of the relay under test.

6. The tester according to claim 5, characterized in that: The relay driver board includes a control module, a bus driver for communicating with the function expansion board, and a relay array; The control module selects the corresponding relay array to realize the output voltage of the corresponding excitation according to the power supply requirements of the relay under test in the analysis content; the relay array is composed of multiple groups of relays, each group of relays includes multiple relays, one end of each relay switch is connected to a relay driving voltage of a specification, and the other end of the switch is incorporated into the total output terminals CH1+ and CH1G; the output terminals CH1+ and CH1G of each group of relays are respectively connected to the two ends of the coil of the relay under test.

7. The tester according to claim 6, characterized in that: The test host compares the current test instruction with the next test instruction when sending the test instruction, and requires in the instruction that the same relay that needs to be closed in both tests maintains the same state.

8. The tester according to claim 3 or 6, characterized in that: The control module records the number of times each relay is used. Each time the relay is closed, the number of times the relay is used is updated. At the same time, the relay number and the number of times used are stored, and a reminder is given when the relay reaches the end of its life and needs to be replaced.

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