Multi-channel flat cable probe conductivity test platform

Abstract

The invention aims to provide a multi-channel flat cable probe conductivity test platform. The device comprises a to-be-tested flat cable and probe module, a constant current source, a voltage acquisition board and a relay switch, the constant current source, the voltage acquisition board and the relay switch are all connected with the to-be-tested flat cable and probe module, and the constant current source outputs a constant current value to drive the voltage acquisition board to acquire voltage. The relay switch switches the corresponding positions of the flat cable to be measured and the probe module, the impedance flowing through the corresponding positions of the flat cable to be measured and the probe module is calculated according to the Ohm's law, and the sum of the impedance and the externally applied rated resistance value is equal to the impedance flowing through the whole flat cable to be measured and the probe module. And on-off of the whole line is judged according to the impedance. The method is applied to the technical field of on-short circuit testing.

Description

Technical Field

[0001] The present invention is applied to the technical field of open and short circuit testing, and particularly relates to a multi-channel wire harness probe conductivity testing platform. Background Art

[0002] Most of the existing open and short circuit tests are manually measured with a multimeter. As the number of probe blocks increases, the test workload gradually increases, the work efficiency is relatively low, and too much manpower is consumed. Since the volume of the probe block is relatively small, manual point measurement is required, so the error rate is relatively high. The existing technology is to use a handheld multimeter to point-measure the open and short circuit conditions of the circuit network. Since each wire harness circuit network has an average of more than 20 pairs, the corresponding network conditions need to be checked for each test. Obviously, a lot of manpower and time costs are required, and it is difficult to achieve production capacity. At the same time, it is easy to point to the wrong position. In addition, since the circuit network intervals between wire harnesses are very short and the pin positions are very small, it is difficult to achieve 100% accuracy in point-measuring the open and short circuits of the wire harness. Therefore, it is necessary to provide a multi-channel wire harness probe conductivity testing platform that uses a constant current source to output a constant current, a DMM voltage acquisition board to measure the voltage values at both ends of the wire harness, and calculates the impedance of the entire line, and judges the open and short circuits of the entire line by obtaining the impedance value. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a multi-channel wire harness probe conductivity testing platform that uses a constant current source to output a constant current, a DMM voltage acquisition board to measure the voltage values at both ends of the wire harness, and calculates the impedance of the entire line, and judges the open and short circuits of the entire line by obtaining the impedance value.

[0004] The technical solution adopted by the present invention is as follows: The present invention includes a wire harness to be tested, a probe module, a constant current source, a voltage acquisition board, and a relay switch. The constant current source, the voltage acquisition board, and the relay switch are all connected to the wire harness to be tested and the probe module. The constant current source outputs a constant current value to drive the voltage acquisition board to collect the voltage magnitude of the wire harness to be tested and the probe module. The relay switch switches the positions of the corresponding wire harness to be tested and the probe module, calculates the impedance flowing through the corresponding position of the wire harness to be tested and the probe module according to Ohm's law, and the sum of the impedance flowing through the corresponding position of the wire harness to be tested and the probe module plus the rated resistance value applied externally is equal to the impedance flowing through the entire wire harness to be tested and the probe module. The open and short circuits of the entire line are judged by the magnitude of the impedance.

[0005] As can be seen from the above solution, in this application, a constant current source outputs a constant current. A relay switch is used to switch the positions of the cable under test and the probe module, so as to obtain the corresponding cable circuit. Then, a voltage acquisition board is used to measure the voltage values at both ends of the cable under test and the probe module. According to Ohm's law, the impedance value flowing through the corresponding position of the cable under test and the probe module is calculated. Adding the rated resistance value applied externally is equal to the impedance value flowing through the entire cable under test and the probe module. The continuity of the entire circuit is judged based on the obtained impedance value. The output is adjustable, and the magnitude of the constant current source can be changed by setting the voltage magnitude of the DAC.

[0006] One preferred solution is that the constant current source includes a low dropout regulator. The two ends of the cable under test and the probe module are respectively the constant current source P port and the constant current source N port. The constant current source P port is connected to the input power supply, the constant current source N port is connected to the IN end of the low dropout regulator, and the SET end of the low dropout regulator serves as the DAC_OUTA end.

[0007] One preferred solution is that the constant current source P port is divided into two paths. One path is connected to the input power supply through a jumper resistor, and the other path is grounded through a first decoupling capacitor. The IN end of the low dropout regulator is grounded through a second decoupling capacitor and a third decoupling capacitor.

[0008] One preferred solution is that the voltage acquisition board includes a first operational amplifier and a second operational amplifier. The output end of the first operational amplifier is connected to the input end of the second operational amplifier. Pin 6 and pin 7 of the first operational amplifier are respectively connected to a first resistor and a second resistor. Pin 2 and pin 3 of the first operational amplifier are connected to a third resistor. Pin 5 and pin 8 of the first operational amplifier are respectively connected to a first capacitor and a second capacitor.

[0009] One preferred solution is that the multi-channel cable probe conductivity test platform further includes an MCU control board. The DAC_OUTA end of the MCU control board is connected to the SET end of the low dropout regulator.

[0010] One preferred solution is that the multi-channel cable probe conductivity test platform further includes an analog-to-digital converter. The SPI end of the analog-to-digital converter is connected to the SET end of the MCU control board. Description of the Drawings

[0011] Figure 1 is the system block diagram of the present invention; Figure 2 is the circuit schematic diagram of the present invention; Figure 3 is the circuit schematic diagram of the constant current source output circuit; Figure 4 is the circuit schematic diagram of the voltage acquisition board; Figure 5 is the simulation diagram of the constant current source output circuit; Figure 6 is the simulation result diagram of the constant current source output circuit; Figure 7 is the audio signal test path diagram in the input mode of the present invention. Detailed implementation manners

[0012] As Figures 1 to 7 shown, in this embodiment, the present invention includes a to-be-tested flexible cable and a probe module 1, a constant current source 2, a voltage acquisition board 3, and a relay switch 4. The constant current source 2, the voltage acquisition board 3, and the relay switch 4 are all connected to the to-be-tested flexible cable and the probe module 1. The constant current source 2 outputs a constant current value to drive the voltage acquisition board 3 to acquire the voltage magnitude of the to-be-tested flexible cable and the probe module 1. The relay switch 4 switches the position of the corresponding to-be-tested flexible cable and the probe module 1, calculates the impedance flowing through the position of the corresponding to-be-tested flexible cable and the probe module 1 according to Ohm's law, and the sum of the impedance flowing through the position of the corresponding to-be-tested flexible cable and the probe module 1 plus the rated resistance value applied externally is equal to the impedance flowing through the entire to-be-tested flexible cable and the probe module 1, and determines the continuity of the entire line through the magnitude of the impedance.

[0013] As Figure 1 and Figure 3 shown, in this embodiment, the constant current source 2 includes a low dropout regulator U700. The two ends of the to-be-tested flexible cable and the probe module 1 are respectively a constant current source P port CC_Source_P and a constant current source N port CC_Source_N. The constant current source P port CC_Source_P is connected to the input power supply PP1V8, the constant current source N port CC_Source_N is connected to the IN end of the low dropout regulator U700, and the SET end of the low dropout regulator U700 is used as the DAC_OUTA end. The model of the low dropout regulator U700 is LT3080EST#PEF.

[0014] As Figure 1 and Figure 3 shown, in this embodiment, the constant current source P port is divided into two paths. One path is connected to the input power supply PP1V8 through a jumper resistor R709, and the other path is grounded through a first decoupling capacitor C705. The IN end of the low dropout regulator U700 is grounded through a second decoupling capacitor C706 and a third decoupling capacitor C707.

[0015] The OUT terminal of the low-dropout regulator U700 is connected to a fourth resistor R710. The second decoupling capacitor C706 and the third decoupling capacitor C707 are both used to reduce the noise at the input terminal. An adjustable voltage value of 0 to 5V is output through DAC_OUTA, and the magnitude of the constant current source is calculated through the resistance value of the fourth resistor R710 according to Ohm's law. The magnitude of the constant current source = DAC_OUTA / R710.

[0016] As Figure 1 and Figure 4 shown, in this embodiment, the voltage acquisition board 3 includes a first operational amplifier U7 and a second operational amplifier U3A. The output terminal of the first operational amplifier U7 is connected to the input terminal of the second operational amplifier U3A. The pin 6 and pin 7 of the first operational amplifier U7 are respectively connected to a first resistor R14 and a second resistor R17. The pin 2 and pin 3 of the first operational amplifier U7 are respectively connected to the first resistor R14 and the second resistor R17. The pin 2 and pin 3 of the first operational amplifier U7 are connected to a third resistor R5. The pin 5 and pin 8 of the first operational amplifier U7 are respectively connected to a first capacitor C36 and a second capacitor C48.

[0017] The model of the first operational amplifier U7 is AD8221, and the model of the second operational amplifier U3A is AD8639. The supply power voltage of the first operational amplifier U7 is powered by ±2.3 V to ±18 V. The single-supply power voltage of the second operational amplifier U3A is 5V to 16V, and the dual-supply power voltage is ±2.5 V to ±8 V. The first operational amplifier U7 can suppress broadband interference and line harmonics. The third resistor R5 is Rg, and Rg is a variable gain resistor. The value of Rg can be obtained from the formula G = 1 + 49.4K / Rg as Rg = 49.4K / (200 - 1) = 249R.

[0018] The first resistor R14 and the second resistor R17 are both used to adjust the output voltage. The first capacitor C36 and the second capacitor C48 are decoupling capacitors close to the power supply pins. This circuit uses a dual-supply operational amplifier circuit to set the reference voltage of the first operational amplifier U7. The output signal of the first operational amplifier U7 is taken from the OUT pin and the REF pin. Two 10kΩ resistors and a 249Ω resistor form a signal attenuation circuit, and the 8V signal can be adjusted to +4 V during design.

[0019] As Figure 7 shown, in this embodiment, the magnitude of the Io constant current source = V1(DAC_OUTA) / R5.

[0020] As Figure 1 and Figure 3As shown, in this embodiment, the multi-channel flexible cable probe conductivity test platform further includes an MCU control board, and the DAC_OUTA terminal of the MCU control board is connected to the SET terminal of the low-dropout regulator U700.

[0021] As Figure 1 and Figure 3 As shown, in this embodiment, the multi-channel flexible cable probe conductivity test platform further includes an analog-to-digital converter, and the SPI terminal of the analog-to-digital converter is connected to the SET terminal of the MCU control board.

[0022] Although the embodiments of the present invention are described with actual solutions, they do not constitute a limitation to the meaning of the present invention. For those skilled in the art, modifications to its implementation solutions according to this specification and combinations with other solutions are obvious.

Claims

1. A multi-channel cable probe continuity test platform, comprising a cable to be tested and a probe module (1), characterized in that: The multi-channel cable probe conductivity test platform also includes a constant current source (2), a voltage acquisition board (3), and a relay switch (4). The constant current source (2), the voltage acquisition board (3), and the relay switch (4) are all connected to the cable to be tested and the probe module (1). The constant current source (2) outputs a constant current value to drive the voltage acquisition board (3) to collect the voltage of the cable to be tested and the probe module (1). The relay switch (4) switches the corresponding position of the cable to be tested and the probe module (1). According to Ohm's law, the impedance flowing through the corresponding position of the cable to be tested and the probe module (1) is calculated. The total value of the impedance plus the rated resistance value applied externally is equal to the impedance flowing through the entire cable to be tested and the probe module (1). The on / off of the entire circuit is judged by the size of the impedance.

2. The multi-channel wiring probe continuity test platform according to claim 1, characterized in that: The constant current source (2) comprises a low voltage dropout regulator (U700), and the two ends of the tested cable and the probe module (1) are respectively a constant current source P port (CC_Source_P) and a constant current source N port (CC_Source_N), the constant current source P port (CC_Source_P) is connected to an input power supply (PP1V8), the constant current source N port (CC_Source_N) is connected to an IN end of the low voltage dropout regulator (U700), and the SET end of the low voltage dropout regulator (U700) serves as a DAC_OUTA end.

3. The multi-channel wiring probe continuity test platform according to claim 2, characterized in that: The constant current source P port (CC_Source_P) is divided into two paths, one path is connected to the input power supply (PP1V8) through a jumper resistor (R709), and the other path is grounded through a first decoupling capacitor (C705). The IN end of the low voltage dropout regulator (U700) is grounded through a second decoupling capacitor (C706) and a third decoupling capacitor (C707).

4. The multi-channel wiring probe continuity test platform according to claim 1, characterized in that: The voltage acquisition board (3) comprises a first operational amplifier (U7) and a second operational amplifier (U3A), the output end of the first operational amplifier (U7) is connected to the input end of the second operational amplifier (U3A), pins 6 and 7 of the first operational amplifier (U7) are respectively connected to a first resistor (R14) and a second resistor (R17), pins 2 and 3 of the first operational amplifier (U7) are respectively connected to a third resistor (R5), and pins 5 and 8 of the first operational amplifier (U7) are respectively connected to a first capacitor (C36) and a second capacitor (C48).

5. The multi-channel wiring probe continuity test platform according to claim 2, characterized in that: The multi-channel wiring probe continuity test platform also includes an MCU control board, and a DAC_OUTA terminal of the MCU control board is connected to a SET terminal of the low-dropout regulator (U700).

6. The multi-channel wiring probe continuity test platform according to claim 5, characterized in that: The multi-channel wiring probe continuity test platform also includes an analog-to-digital converter, and the SPI end of the analog-to-digital converter is connected to the SET end of the MCU control board.

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