Self-checking system and method of multi-channel low-input-impedance A / D sampling circuit

Abstract

The invention relates to the technical field of automatic measurement and control, and provides a self-checking system and method for a multi-channel low-input-impedance A / D sampling circuit, which do not need to add a plurality of current-limiting resistors, can be directly connected to a standard voltage source in parallel, and is low in current consumption and high in safety. During self-checking, after the switch K1 is switched off, the input impedance of the A / D sampling circuit is increased, the A / D sampling circuit can be directly connected to a standard voltage source in parallel, the current consumption is small, the safety is high, 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. In the self-checking mode, the input impedance of the A / D sampling circuit is changed to be a high value, so that errors caused by an internal signal path can be reduced, and a more accurate measurement result can be obtained.

Description

Technical Field

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

[0002] In many existing test systems, it is necessary to measure and detect large current signals of multiple channels. Generally, the current measurement is completed by using a multi-channel A / D sampling circuit plus a load resistor. The usual way to self-check the A / D sampling circuit is to make a dedicated self-check cable or self-check device, short-circuit all the input terminals of the A / D sampling, and then connect them together to a standard voltage source. The sampling voltage value is compared with the standard voltage through the self-check software to determine whether the sampling circuit is working properly. This brings a problem. If the A / D sampling circuit with a very low input impedance (tens of ohms to several ohms) is short-circuited 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. It brings challenges to the self-check of the test system circuit itself.

[0003] It can be seen that 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 line, and a current limiting resistor needs to be added to the input end of each sampling circuit during self-test, which brings difficulties to the production and specific operation of the self-test cable. Summary of the invention

[0004] In view of this, the present invention provides a self-test system and method for a multi-channel low-input impedance A / D sampling circuit, which does not require the addition of multiple current-limiting resistors and can be directly connected in parallel to a standard voltage source, consumes little current and has high safety.

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

[0006] A self-test system for a multi-pass low-input impedance A / D sampling circuit, comprising: a standard voltage source, a load resistor, a switch K1, a self-test cable and a reference ground terminal AGND of the sampling circuit;

[0007] Among them, the standard voltage source is used to provide a reference standard voltage to the sampling circuit during self-test; the negative ends of each load resistor 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 resistor from the reference ground AGND of the sampling circuit during self-test; the self-test cable is used to short-circuit the input end of each A / D sampling circuit in the self-test state and connect it to an external standard voltage source.

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

[0009] When the system is in the self-test state, the normally closed node of the switch K1 is disconnected, and the sampling circuit is allowed to perform voltage sampling and self-test.

[0010] The system also includes control logic for automatically controlling the state switching of the switch K1 and coordinating various operations during the self-test process.

[0011] The switch K1 is an electronic switch or a mechanical switch.

[0012] The self-test cable includes enough wires to connect the input ends of all A / D sampling circuits.

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

[0014] The present invention also provides a self-test method for a multi-pass low input impedance A / D sampling circuit, which is implemented based on the self-test system of the present invention and includes the following steps:

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

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

[0017] Wherein, in the self-test mode, the following steps are further included: evaluating the data obtained from the A / D sampling circuit to determine whether the circuit functions normally.

[0018] The following steps are also included: if the self-test result shows an abnormality, the fault information is recorded for subsequent analysis and maintenance.

[0019] Beneficial effects:

[0020] 1. The system of the present invention only needs to add a normally open node of one switch, and there is no need to add multiple current limiting resistors on the self-test cable; during self-test, after the switch K1 is disconnected, the input impedance of the A / D sampling circuit becomes larger, and it can be directly connected to the standard voltage source in parallel, with low current consumption and high safety. It can solve the self-test problem of multi-channel low input impedance A / D sampling circuits and improve the safety and reliability of sampling circuits and self-test circuits. When in self-test 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 a more accurate measurement result.

[0021] 2. The self-test system of the present invention allows the test to be performed without interfering with normal working conditions, ensuring that the system can maintain its expected functional performance even during the self-test process. This helps to detect potential problems more accurately and reduce the possibility of false alarms; 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 deviation or fault point.

[0022] 3. In the system of the present invention, since the self-test cable can short-connect the input terminals of all A / D sampling circuits to a standard voltage source, this design makes it possible to test multiple channels at one time, reducing the time and complexity required to check each channel one by one.

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

[0024] 5. The method of the present invention is implemented based on the system of the present invention. It is not necessary to add multiple current limiting resistors to the self-test cable. During self-test, after the switch K1 is disconnected, the input impedance of the A / D sampling circuit becomes larger, and it can be directly connected to the standard voltage source in parallel, with low current consumption and high safety. It can solve the self-test problem of multi-channel low input impedance A / D sampling circuits and improve the safety and reliability of sampling circuits and self-test circuits. When in self-test 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 a more accurate measurement result.

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

[0026] Figure 1 This is a schematic diagram of the system of the present invention. DETAILED DESCRIPTION

[0027] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0028] The present invention provides a self-test system for a multi-channel low input impedance A / D sampling circuit, which can solve the self-test 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-test circuit. Figure 1 As shown, it includes: a standard voltage source, a load resistor, a switch K1, a self-test cable and a reference ground terminal AGND of a sampling circuit; wherein the standard voltage source is used to provide a reference standard voltage to the sampling circuit during self-test; the negative ends 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 a normally closed node of the switch K1; the switch K1 is used to isolate the negative common terminal COM- of the load resistor from the reference ground AGND of the sampling circuit during self-test.

[0029] When the system is normally detected and used, 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 end of the load resistor is connected to the reference ground of the sampling circuit, and the current signal can be detected and sampled normally; when the system is in the self-test state, an external self-test cable is connected, and the self-test cable short-circuits the input ends of each A / D sampling circuit and connects them to an external standard voltage source. Specifically, when performing a self-test operation, the input ends (AD-1~AD-N) of the multi-channel sampling circuit are connected together through the self-test cable and connected to a standard voltage source; the normally closed node of switch K1 is disconnected, so that the input impedance of the A / D sampling circuit becomes high, thereby protecting the standard voltage source. At this time, the sampling circuit can be normally sampled and self-tested.

[0030] The present invention also provides a self-test method for a multi-channel low input impedance A / D sampling circuit, which is implemented based on the system of the present invention and includes the following steps:

[0031] In the normal working mode, the switch K1 is kept turned on so that the negative end of the load resistor is connected to the reference ground of the sampling circuit to perform conventional current and voltage signal sampling;

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

[0033] In the self-test mode, the following steps are further included: evaluating the data obtained from the A / D sampling circuit to determine whether the circuit functions normally.

[0034] If the self-test results show an abnormality, record the fault information for subsequent analysis and maintenance.

[0035] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A self-test system for a multi-pass low input impedance A / D sampling circuit, characterized in that: include: Standard voltage source, load resistor, switch K1, self-test cable and reference ground terminal AGND of sampling circuit; The standard voltage source is used to provide a reference standard voltage to the sampling circuit during self-test; the negative ends 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 resistor from the reference ground AGND of the sampling circuit during self-test; The self-test cable is used to short-circuit the input ends of each A / D sampling circuit and connect them to an external standard voltage source in the self-test state.

2. The system according to claim 1, characterized in that The switch K1 is always in the on state, so that the negative end of the load resistor is connected to the reference ground of the sampling circuit to perform normal current and voltage signal sampling and detection.

3. The system according to claim 2, characterized in that ,When the system is in the self-test state, the normally closed node of the switch K1 is disconnected, and the sampling circuit is allowed to perform voltage sampling and self-test.

4. The method according to any one of claims 1 to 3, characterized in that ,The system also includes a control logic for automatically controlling the ,state switching of the switch K1 and coordinating various operations during the ,self-test process.

5. The system according to claim 4, characterized in that The switch K1 is an electronic switch or a mechanical switch.

6. The system according to claim 4, characterized in that The self-test cable contains enough wires to connect the input terminals of all A / D sampling circuits.

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

8. A self-test method for a multi-pass low input impedance A / D sampling circuit, characterized in that: The self-checking system according to any one of claims 1 to 7 is implemented, comprising the following steps: In the normal working mode, the switch K1 is kept turned on, so that the negative end of the load resistor is connected to the reference ground of the sampling circuit to perform conventional current and voltage signal sampling; In the self-test mode, the input terminals of multiple A / D sampling circuits are short-circuited and connected to a standard voltage source through the self-test cable; the normally closed node of switch K1 is disconnected to increase the input impedance of the A / D sampling circuit, and voltage sampling and self-test of the A / D sampling circuit are started.

9. The method according to claim 8, characterized in that In the self-test mode, the following steps are further included: evaluating the data obtained from the A / D sampling circuit to determine whether the circuit functions normally.

10. The method according to claim 8 or 9, characterized in that The method also includes the following steps: if the self-test result shows an abnormality, the fault information is recorded for subsequent analysis and maintenance.

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