Self-test system and method for a multi-channel low input impedance a / d sampling circuit

Abstract

The present application relates to the technical field of automatic measurement and control, and provides a self-checking system and method of a multi-channel low input impedance A / D sampling circuit, which can be directly connected in parallel to a standard voltage source without increasing a plurality of current limiting resistors, consumes small current and has high safety. When self-checking, after the switch K1 is disconnected, the input impedance of the A / D sampling circuit becomes large, the A / D sampling circuit can be directly connected in parallel to the standard voltage source, consumes small current and has high safety, the self-checking problem of the multi-channel low input impedance A / D sampling circuit can be solved, and the safety and reliability of the sampling circuit and the self-checking circuit are improved. When in the self-checking mode, by changing the input impedance of the A / D sampling circuit to a higher value, the error caused by the internal signal path can be reduced, so that more accurate measurement results can be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automatic measurement and control, in particular to a self-checking system and method of a multi-channel low input impedance A / D sampling circuit. BACKGROUND

[0002] In many existing test systems, the large current signals of multiple channels need to be measured and detected. Generally, the measurement of the current is completed by using a multi-channel A / D sampling circuit plus load resistors. The common way to self-check the A / D sampling circuit is to make a special self-checking cable or self-checking device, short all the input ends of the A / D sampling, and then connect them to a standard voltage source. The sampled voltage value is compared with the standard voltage by self-checking software to determine whether the sampling circuit is working properly. This brings a problem that if the A / D sampling circuit with low input impedance (a few tens of ohms to a few ohms) is shorted in parallel, the input impedance will become lower. When the standard voltage source is connected, the current will become very large, the heat will also be large, and there will be certain safety hazards. This brings challenges to the self-checking of the test system circuit itself.

[0003] As can be seen, in the prior art, the negative end of the load resistor of the multi-channel A / D sampling circuit is directly connected to the sampling reference ground, and a current limiting resistor needs to be added to the input end of each sampling circuit during self-checking. This brings difficulty to the production and specific operation of the self-checking cable. SUMMARY

[0004] Therefore, the present application provides a self-checking system and method of a multi-channel low input impedance A / D sampling circuit, which does not need to add multiple current limiting resistors, can be directly connected to a standard voltage source, consumes small current, and is safe.

[0005] To achieve the above purpose, the technical scheme of the present application is as follows:

[0006] A self-checking system of a multi-channel low input impedance A / D sampling circuit, comprising: a standard voltage source, load resistors, a switch K1, a self-checking cable, and a reference ground end AGND of the sampling circuit.

[0007] The standard voltage source is used to provide a reference standard voltage to the sampling circuit during self-checking. The negative poles of the load resistors are connected together as a negative common end COM-. The negative common end COM- is connected to the reference ground end AGND of the sampling circuit through the normally closed node of the switch K1. The switch K1 is used to isolate the negative common end COM- of the load resistors from the reference ground AGND of the sampling circuit during self-checking. The self-checking cable is used to short the input ends of the A / D sampling circuits and connect them to the externally connected standard voltage source in the self-checking state.

[0008] Wherein, the switch K1 is always in the on state, so that the negative end of the load resistance and the sampling circuit reference ground are connected together to perform normal current and voltage signal sampling and detection.

[0009] Wherein, when the system is in the self-checking state, the voltage sampling and self-checking of the sampling circuit are allowed by opening the normally closed node of the switch K1.

[0010] Wherein, the system further comprises control logic for automatically controlling the state switching of the switch K1 and coordinating the operations in the self-checking process.

[0011] Wherein, the switch K1 is an electronic switch or a mechanical switch.

[0012] Wherein, the self-checking cable contains a sufficient number of wires to connect the input ends of all A / D sampling circuits.

[0013] Wherein, the standard voltage source, load resistance, switch K1, and self-checking cable are adjusted according to different numbers of A / D sampling circuit channels.

[0014] The present application also provides a self-checking method for a multi-channel low input impedance A / D sampling circuit, which is implemented based on the self-checking system described in the present application and comprises the following steps:

[0015] In the normal working mode, the switch K1 is kept on, so that the negative end of the load resistance is connected to the reference ground of the sampling circuit to perform normal current and voltage signal sampling.

[0016] In the self-checking mode, the input ends of the multiple A / D sampling circuits are short-circuited and connected to a standard voltage source through the self-checking cable; the normally closed node of the switch K1 is opened to increase the input impedance of the A / D sampling circuit, and voltage sampling and self-checking of the A / D sampling circuit are started.

[0017] Wherein, in the self-checking mode, the method further comprises the following step: evaluating the data obtained from the A / D sampling circuit to determine whether the function of the circuit is normal.

[0018] Wherein, the method further comprises the following step: if the self-checking result shows an abnormality, recording fault information for subsequent analysis and maintenance.

[0019] Advantages:

[0020] 1.The system of the present application only needs to add a normally open node of a switch, and does not need to add multiple current limiting resistors on the self-checking cable; when self-checking, after the switch K1 is opened, the input impedance of the A / D sampling circuit becomes larger, which can be directly connected in parallel to a standard voltage source, consumes less current, is safe, can solve the self-checking problem of multi-channel low input impedance A / D sampling circuits, and improves the safety and reliability of the sampling circuit and the self-checking circuit. When in the self-checking mode, by changing the input impedance of the A / D sampling circuit to a higher value, the error caused by the internal signal path can be reduced, thereby obtaining more accurate measurement results.

[0021] 2.The self-checking system of the present application allows testing to be performed without interfering with normal working conditions, ensuring that the system can maintain its expected functional performance even during the self-checking process. This helps to more accurately detect potential problems and reduce the likelihood of false positives; and by introducing an external standard voltage source and controlling the switch state, the performance of the A / D converter can be evaluated under known conditions, which helps to more accurately determine any performance deviations or fault points.

[0022] 3.In the system of the present application, since the self-checking cable can short all the input ends of the A / D sampling circuits to a standard voltage source, this design allows multiple channels to be tested at one time, reducing the time and complexity required for checking each channel one by one.

[0023] 4.The present application utilizes existing hardware resources (such as load resistors, switches, etc.) to realize the self-checking function, without the need for additional complex circuits or components, thereby reducing costs while improving efficiency.

[0024] 5.The method of the present application is based on the system of the present application, and does not need to add multiple current limiting resistors on the self-checking cable; when self-checking, after the switch K1 is opened, the input impedance of the A / D sampling circuit becomes larger, which can be directly connected in parallel to a standard voltage source, consumes less current, is safe, can solve the self-checking problem of multi-channel low input impedance A / D sampling circuits, and improves the safety and reliability of the sampling circuit and the self-checking circuit. When in the self-checking mode, by changing the input impedance of the A / D sampling circuit to a higher value, the error caused by the internal signal path can be reduced, thereby obtaining more accurate measurement results.

[0025] 6.The present application is suitable for multi-channel low input impedance A / D sampling circuits and has good compatibility and scalability, and can be conveniently applied to systems of different scales and types. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the schematic diagram of the system of the present application. DETAILED DESCRIPTION

[0027] The application will be described in detail below with reference to the accompanying drawings and examples.

[0028] The application provides a self-checking system of a multi-channel low input impedance A / D sampling circuit, which can solve the self-checking problem of the multi-channel low input impedance A / D sampling circuit and improve the safety and reliability of the sampling circuit and the self-checking circuit. Figure 1 The system principle is shown in the figure, which comprises a standard voltage source, load resistors, a switch K1, a self-checking cable and a reference ground terminal AGND of the sampling circuit; wherein the standard voltage source is used to provide a reference standard voltage for the sampling circuit during self-checking; the negative terminals of the load resistors are connected together as a negative common end COM-; the negative common end COM- is connected to the reference ground terminal AGND of the sampling circuit through the normally closed node of the switch K1; and the switch K1 is used to isolate the negative common end COM- of the load resistors from the reference ground AGND of the sampling circuit during self-checking.

[0029] When the system is normally detected and used, the switch K1 is always in the on state, which does not affect the normal current and voltage signal sampling and detection, that is, during normal testing and use, the negative terminals of the load resistors are connected together with the reference ground of the sampling circuit, so that the current signal can be normally detected and sampled; when the system is in the self-checking state, the self-checking cable is externally connected, the self-checking cable shorts and connects the input terminals of the A / D sampling circuits to the externally connected standard voltage source; specifically, when the self-checking operation is performed, the input terminals (AD-1~AD-N) of the multi-channel sampling circuit are connected together through the self-checking cable and connected to a standard voltage source; the normally closed node of the switch K1 is disconnected, so that the input impedance of the A / D sampling circuit is increased, thereby protecting the standard voltage source, and at this time, the voltage sampling and self-checking of the sampling circuit can be normally performed.

[0030] The application further provides a self-checking method of a multi-channel low input impedance A / D sampling circuit, which is realized based on the system of the application and comprises the following steps:

[0031] In the normal working mode, the switch K1 is kept on, so that the negative terminals of the load resistors are connected with the reference ground of the sampling circuit to perform the normal current and voltage signal sampling;

[0032] In the self-checking mode, the input terminals of the A / D sampling circuits are shorted and connected to a standard voltage source through the self-checking cable; the normally closed node of the switch K1 is disconnected, the input impedance of the A / D sampling circuit is increased, and the voltage sampling and self-checking of the A / D sampling circuit are started.

[0033] In the self-checking mode, the method further comprises the following step: evaluating the data obtained from the A / D sampling circuit to determine whether the function of the circuit is normal.

[0034] If the self-checking result shows an abnormality, fault information is recorded for subsequent analysis and repair.

[0035] To sum up, the above is only the preferred embodiment of the present application, not for limiting the scope of protection of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A self-test system for a multi-channel low input impedance A / D sampling circuit, characterized by, The system comprises: a standard voltage source, load resistors, a switch K1, a self-checking cable and a reference ground terminal AGND of the sampling circuit; wherein the standard voltage source is used to provide a reference standard voltage to the sampling circuit during self-checking; the negative terminals of the load resistors are connected together as a negative common terminal COM-; the negative common terminal COM- is connected to the reference ground terminal AGND of the sampling circuit through the normally closed node of the switch K1; the switch K1 is used to isolate the negative common terminal COM- of the load resistors from the reference ground AGND of the sampling circuit during self-checking; and the self-checking cable is used to short and connect the input terminals of the A / D sampling circuits to an external standard voltage source in the self-checking state. In the normal working mode, the switch K1 is kept on, and the negative terminals of the load resistors are connected to the reference ground of the sampling circuit to perform normal current and voltage signal sampling. In the self-checking mode, the input terminals of the A / D sampling circuits are shorted and connected to a standard voltage source through the self-checking cable; the normally closed node of the switch K1 is opened, the input impedance of the A / D sampling circuit is increased, and voltage sampling and self-checking of the A / D sampling circuit are started.

2. The system of claim 1, wherein, The switch K1 is always in the on state, so that the negative terminals of the load resistors are connected together with the reference ground of the sampling circuit for normal current and voltage signal sampling and detection.

3. The system of claim 2, wherein When the system is in the self-checking state, the normally closed node of the switch K1 is opened, and voltage sampling and self-checking of the sampling circuit are allowed.

4. The system of any of claims 1-3, wherein The system further comprises control logic for automatically controlling the state switching of the switch K1 and coordinating the operations in the self-checking process.

5. The system of claim 4, wherein, The switch K1 is an electronic switch or a mechanical switch.

6. The system of claim 4, wherein, The self-checking cable contains a sufficient number of wires to connect the input terminals of all A / D sampling circuits.

7. The system of claim 5 or 6, wherein, The standard voltage source, load resistors, switch K1 and self-checking cable are adjusted according to different numbers of A / D sampling circuit channels.

8. The system of claim 1, wherein, In the self-checking mode, the data obtained from the A / D sampling circuit is further evaluated to determine whether the circuit is functioning properly.

9. The system of claim 1 or 8, wherein, If the self-checking result shows an abnormality, fault information is recorded for subsequent analysis and maintenance.

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