AC digital quantity acquisition system and method based on PLC

Abstract

The invention discloses an alternating current digital quantity acquisition system and method based on a PLC, relates to the technical field of alternating current signals, adjusts and analyzes related circuit parameters corresponding to each device based on an evaluation coefficient, and can ensure that the circuit parameters are highly adaptive to an acquisition environment of a specific device. For example, in an area with strong electromagnetic interference, the anti-interference capability of the circuit can be intensified in a targeted manner, and the circuit can be optimized to collect signals more stably. Therefore, the reliability and accuracy of the whole acquisition system in different complex industrial environments can be improved, signal acquisition errors or instability caused by environmental factors can be reduced, and whether the alternating current signal function of each device has a fault can be timely and accurately evaluated by comparing with a set standard function evaluation value. Once a fault is found, the fault type analysis module can quickly switch an alternating current signal of fault equipment to a fault detection channel for deep analysis, determine a specific fault type and send out an early warning prompt.

Description

Technical Field

[0001] The present invention relates to the technical field of AC signals, and in particular to a PLC-based AC digital quantity acquisition system and method. Background Art

[0002] Most of the existing industrial field digital quantity acquisition is DC digital quantity acquisition with a voltage range of 0-36V. There are fewer AC digital quantity acquisition methods, and the electromagnetic environment of the industrial field is relatively complex. The collected signals are easily affected by the external environment, resulting in inconsistency between the actual collected signals and the input signals, which has serious consequences in some special application scenarios, especially in the natural gas, chemical and other industries. Therefore, a PLC-based AC digital quantity acquisition system and method is needed.

[0003] Traditional technology is rarely used to collect AC digital signals in industrial automation control field applications. Considering the extremely complex electromagnetic interference environment on site and the limitations of on-site cable laying, the AC signal transmission and collection process is prone to mutual interference between signals, fluctuations in the voltage of the AC digital input signal, and non-isolation of the AC digital input signal. As a result, the collected values ​​of the AC digital signal are prone to flipping and fluctuations. Obviously, this collection method has at least the following problems: 1. The existing technology lacks a mechanism for acquiring and evaluating data specifically for the impact of the AC signal collection environment on each device. It is difficult to accurately know the specific impact of factors such as electromagnetic interference intensity, signal fluctuation range, and peak voltage size on the collection system, and it is impossible to provide a reliable basis for subsequent adjustments. It is difficult to make targeted adjustments and optimizations to related circuit parameters according to the actual collection environment of different devices, resulting in poor adaptability of the collection system in complex and changeable industrial environments, and prone to problems such as inaccurate and unstable signal collection, affecting the reliability and accuracy of the entire system.

[0004] 2. It is difficult for the existing technology to simultaneously obtain multi-dimensional functional data such as constant current source output current, feedback voltage, emitter voltage and acquisition voltage change rate to comprehensively judge the functional status of the equipment AC signal. There may be an incomplete and inaccurate evaluation of the equipment function, and it is impossible to timely discover potential fault hazards. When the equipment AC signal fails, there is a lack of fast and effective fault switching and analysis mechanism, and the fault signal cannot be quickly switched to a dedicated detection channel for in-depth analysis, resulting in a long fault location time. Maintenance personnel need to spend a lot of time and energy to investigate the cause of the fault, which prolongs equipment downtime, reduces production efficiency, and increases maintenance costs.

[0005] 3. Traditional data collection methods may have limitations in collection accuracy, real-time performance, and data processing capabilities. They are unable to perform high-precision, high-frequency sampling and rapid processing of AC signals, resulting in the collected data not being able to accurately reflect the true operating status of the equipment, affecting the accuracy of equipment performance assessment and fault diagnosis. At the same time, without accurate environmental impact assessment and fault diagnosis, excessive maintenance, blind equipment replacement, or unnecessary circuit parameter adjustments may occur, resulting in waste of resources and increased costs, which is not conducive to the company's optimal resource allocation and economic efficiency improvement. Summary of the invention

[0006] In view of the above-mentioned technical deficiencies, the object of the present invention is to provide an AC digital quantity acquisition system and method based on PLC.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a PLC-based AC digital quantity acquisition system, including: an environmental impact data acquisition module: used to obtain the collected environmental impact data corresponding to the AC signal of each device in the programmable logic controller of the target enterprise, the environmental impact data including the electromagnetic interference intensity, signal fluctuation range and peak voltage size, so as to analyze and obtain the collected environmental impact assessment coefficient corresponding to the AC signal of each device.

[0008] Related circuit parameter adjustment module: used to adjust and analyze the related circuit parameters corresponding to each device according to the collection environment impact assessment coefficient corresponding to the AC signal of each device.

[0009] AC digital signal function judgment module: used to obtain the functional data corresponding to the AC signal of each device. The functional data includes the constant current source output current, feedback voltage, emitter voltage and acquisition voltage change rate, so as to analyze and obtain the functional evaluation value corresponding to the AC signal of each device, and then evaluate whether the AC signal function of each device is faulty.

[0010] Fault type analysis module: When a device's AC signal function fails, the device's AC signal is switched to the fault detection channel, and then the fault type corresponding to the device's AC signal is analyzed, and an early warning prompt is issued.

[0011] Preferably, the acquisition of the collection environment impact data corresponding to the AC signal of each device in the programmable logic controller of the target enterprise is carried out as follows: A1. The probe of the spectrum analyzer is placed near the AC signal collection point of each device, and a suitable frequency range and resolution bandwidth are set. During the normal operation of the equipment, multiple time periods are measured to record the electromagnetic interference intensity at different frequencies.

[0012] A2. Connect the probe of the oscilloscope to the signal acquisition input terminal of the PLC of each device's AC signal, set the trigger mode of the oscilloscope to an appropriate mode, and continuously record the signal waveform for a period of time during the operation of the equipment, obtain the maximum and minimum values ​​of the waveform, and calculate the difference between the maximum and minimum values ​​of the waveform, and record the difference as the signal fluctuation range.

[0013] A3. Use the peak detection function of the oscilloscope to capture the peak voltage. After connecting the oscilloscope probes of each device and setting the basic parameters, turn on the peak detection function of the oscilloscope. Automatically detect the positive and negative peaks in the signal. During the operation of the device, pay attention to the peak voltage displayed by the oscilloscope. At the same time, set the storage depth of the oscilloscope to record the signal peak over a longer period of time.

[0014] Preferably, the analysis obtains the collection environment impact assessment coefficient corresponding to the AC signal of each device. The specific analysis process is as follows: the electromagnetic interference intensity, signal fluctuation range and peak voltage size corresponding to the AC signal of each device are recorded as , and ,in, Indicates the number corresponding to the AC signal of each device. , u is any integer greater than 2, substitute it into the calculation formula: The collection environment impact assessment coefficient corresponding to the AC signal of each device is obtained ,in, , , They are the standard electromagnetic interference intensity, standard signal fluctuation range, and standard peak voltage size corresponding to the set device AC signal. , , They are respectively the weight factor corresponding to the electromagnetic interference intensity of the AC signal of the set equipment, the weight factor corresponding to the signal fluctuation range, and the weight factor corresponding to the peak voltage size, and e represents a natural constant.

[0015] Preferably, the relevant circuit parameters corresponding to each device are adjusted and analyzed, and the specific adjustment process is as follows: the acquisition environment impact assessment coefficient corresponding to the AC signal of each device is compared with the acquisition environment impact assessment coefficient interval corresponding to each relevant circuit parameter adjustment value in the database. If the acquisition environment impact assessment coefficient corresponding to the AC signal of a certain device is within the acquisition environment impact assessment coefficient interval corresponding to a certain relevant circuit parameter adjustment value in the database, then the relevant circuit parameter adjustment value in the database is used as the relevant circuit parameter adjustment value corresponding to the device. In this way, the relevant circuit parameters corresponding to each device are adjusted and analyzed.

[0016] Preferably, the functional data corresponding to the AC signal of each device is obtained, and the functional data includes the constant current source output current, feedback voltage, emitter voltage and acquisition voltage change rate. The specific acquisition process is as follows: B1. Connect a digital ammeter in series to the constant current source output circuit of each device, and directly read the value displayed by the ammeter to obtain the size of the constant current source output current.

[0017] B2. Connect the probe of the digital voltmeter to the output terminal of the feedback voltage of each device, and directly read the value displayed on the voltmeter to obtain the size of the feedback voltage.

[0018] B3. Use a voltmeter to directly connect the probe between the emitter of each device's transistor and the ground, and directly read the value displayed on the voltmeter to get the emitter voltage.

[0019] B4. Use the cursor function of the oscilloscope to measure the voltage change rate. After the voltage waveform is displayed on the oscilloscope of each device, enable the cursor function and place two cursors at two different positions on the waveform. The oscilloscope will display the time and voltage values ​​corresponding to the two cursor positions. By adjusting the cursor positions, calculate the voltage difference and time interval between different positions. Divide the voltage difference between different positions by the time interval to get the voltage change rate.

[0020] Preferably, the analysis obtains the function evaluation value corresponding to the AC signal of each device, and the specific analysis process is as follows: the constant current source output current, feedback voltage, emitter voltage and acquisition voltage change rate corresponding to the AC signal of each device are recorded as , , and ,in, Indicates the number corresponding to the AC signal of each device. , u is any integer greater than 2, substitute it into the calculation formula: The functional evaluation value corresponding to the AC signal of each device is obtained ,in, , , , They are the standard constant current source output current, standard feedback voltage, standard emitter voltage, and standard acquisition voltage change rate corresponding to the set device AC signal. , , , They are the weight factors corresponding to the output current of the AC signal constant current source of the set device, the weight factor corresponding to the feedback voltage, the weight factor corresponding to the emitter voltage, and the weight factor corresponding to the acquisition voltage change rate. , , , They are respectively the permitted constant current source output current difference, permitted feedback voltage difference, permitted emitter voltage difference, and permitted acquisition voltage change rate difference corresponding to the set device AC signal.

[0021] Preferably, the evaluation of whether the AC signal function of each device is faulty is specifically analyzed as follows: the function evaluation value corresponding to the AC signal of each device is compared with the function evaluation value corresponding to the set standard device AC signal. If the function evaluation value corresponding to the AC signal of a certain device is greater than or equal to the function evaluation value corresponding to the set standard device AC signal, then it is evaluated that the AC signal function of the device is faulty; if the function evaluation value corresponding to the AC signal of a certain device is less than the function evaluation value corresponding to the set standard device AC signal, then it is evaluated that the AC signal function of the device is not faulty. In this way, it is evaluated whether the AC signal function of each device is faulty.

[0022] Preferably, the AC signal of the device is switched to the fault detection channel, and the specific switching process is as follows: when the AC signal function of a certain device fails, after the switching circuit receives the fault trigger signal, the control circuit will process the signal, and the optocoupler relay will act as a switching switch. The fault trigger signal passes through a drive circuit to provide current and voltage to ensure that the optocoupler relay can operate normally. The switching switch switches the device AC signal from the normal transmission channel to the fault detection channel.

[0023] Preferably, the specific analysis process of analyzing the fault type corresponding to the AC signal fault of the device is as follows: comparing the functional evaluation value corresponding to the device with the functional evaluation value corresponding to each fault type in the database; if the functional evaluation value corresponding to the device is the same as the functional evaluation value corresponding to a certain fault type in the database, then the fault type in the database is recorded as the fault type corresponding to the AC signal fault of the device. In this way, the fault type corresponding to the AC signal fault of the device is analyzed.

[0024] In a second aspect, the present invention provides a PLC-based AC digital quantity acquisition method, comprising: step one, obtaining environmental impact data: obtaining the collected environmental impact data corresponding to the AC signal of each device in the target enterprise's programmable logic controller, the environmental impact data including electromagnetic interference intensity, signal fluctuation range and peak voltage size, thereby analyzing and obtaining the collection environmental impact assessment coefficient corresponding to the AC signal of each device.

[0025] Step 2: Adjustment of relevant circuit parameters: According to the acquisition environmental impact assessment coefficient corresponding to the AC signal of each device, the relevant circuit parameters corresponding to each device are adjusted and analyzed.

[0026] Step 3. Determine the function of the AC digital signal: obtain the functional data corresponding to the AC signal of each device, the functional data includes the constant current source output current, feedback voltage, emitter voltage and acquisition voltage change rate, so as to analyze and obtain the functional evaluation value corresponding to the AC signal of each device, and then evaluate whether the AC signal function of each device is faulty.

[0027] Step 4: Analysis of fault type: When a device's AC signal function fails, the device's AC signal is switched to the fault detection channel, and then the fault type corresponding to the device's AC signal is analyzed, and an early warning prompt is issued.

[0028] The beneficial effects of the present invention are: 1. In the embodiment of the present invention, the environmental impact data acquisition module obtains the acquisition environment impact data such as electromagnetic interference intensity, signal fluctuation range and peak voltage in detail, and analyzes the acquisition environment impact assessment coefficient corresponding to the AC signal of each device, so as to accurately understand the actual acquisition environment conditions of each device. Based on the assessment coefficient, the relevant circuit parameters corresponding to each device are adjusted and analyzed to ensure that the circuit parameters are highly adapted to the acquisition environment of the specific device. For example, in areas with strong electromagnetic interference, the anti-interference ability of the circuit can be strengthened in a targeted manner; for devices with large signal fluctuations, the circuit can be optimized to collect signals more stably. This helps to improve the reliability and accuracy of the entire acquisition system in different complex industrial environments, and reduce signal acquisition errors or instabilities caused by environmental factors.

[0029] 2. The embodiment of the present invention can obtain functional data including constant current source output current, feedback voltage, emitter voltage and acquisition voltage change rate, and analyze to obtain the functional evaluation value corresponding to the AC signal of each device, thereby realizing real-time monitoring of the AC signal function of each device. By comparing with the set standard functional evaluation value, it can be timely and accurately evaluated whether the AC signal function of each device is faulty. Once a fault is found, the fault type analysis module can quickly switch the AC signal of the faulty device to the fault detection channel for in-depth analysis, determine the specific fault type and issue an early warning prompt. This efficient fault diagnosis mechanism helps to shorten equipment downtime, improve production efficiency, and reduce maintenance costs. Because the fault point can be quickly located, maintenance personnel can perform repair work more targetedly.

[0030] 3. In the embodiment of the present invention, the system adopts relatively standardized calculation formulas and comparison methods in various links such as obtaining environmental impact data, analyzing evaluation coefficients, adjusting circuit parameters, and judging equipment functions. For example, the evaluation coefficient is calculated by setting standard parameters such as electromagnetic interference intensity, signal fluctuation range, peak voltage size, and corresponding weight factors; the function evaluation value is calculated by setting the standard constant current source output current, feedback voltage, transmitter voltage, acquisition voltage change rate, etc. and corresponding weight factors. This standardized processing method makes the system have better standardization and repeatability, which is convenient for different operators to understand and operate, and is also conducive to the subsequent maintenance and upgrading of the system. At the same time, the system has certain scalability. According to actual needs, the data such as the acquisition environmental impact evaluation coefficient interval corresponding to each relevant circuit parameter adjustment value and the function evaluation value corresponding to each fault type can be continuously updated and expanded in the database to adapt to more types of equipment, more complex working conditions and newly emerging fault conditions, so as to ensure the effectiveness and applicability of the system in different application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a schematic diagram of the connection of the system modules of the present invention.

[0033] Figure 2 The present invention is a flowchart of the steps for implementing the method. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Embodiments of the present invention Figure 1 As shown, a PLC-based AC digital quantity acquisition system includes: an environmental impact data acquisition module, a related circuit parameter adjustment module, an AC digital signal function judgment module, a fault type analysis module and a database.

[0036] Environmental impact data acquisition module: used to obtain the collected environmental impact data corresponding to the AC signals of each device in the target enterprise's programmable logic controller. The environmental impact data includes electromagnetic interference intensity, signal fluctuation range and peak voltage size, so as to analyze and obtain the collected environmental impact assessment coefficient corresponding to the AC signals of each device.

[0037] In a specific embodiment, the acquisition of the collection environment impact data corresponding to the AC signal of each device in the programmable logic controller of the target enterprise is carried out as follows: A1. The probe of the spectrum analyzer is placed near the AC signal collection point of each device, and a suitable frequency range and resolution bandwidth are set. During the normal operation of the equipment, multiple time periods are measured to record the electromagnetic interference intensity at different frequencies.

[0038] A2. Connect the probe of the oscilloscope to the signal acquisition input terminal of the PLC of each device's AC signal, set the trigger mode of the oscilloscope to an appropriate mode, and continuously record the signal waveform for a period of time during the operation of the equipment, obtain the maximum and minimum values ​​of the waveform, and calculate the difference between the maximum and minimum values ​​of the waveform, and record the difference as the signal fluctuation range.

[0039] A3. Use the peak detection function of the oscilloscope to capture the peak voltage. After connecting the oscilloscope probes of each device and setting the basic parameters, turn on the peak detection function of the oscilloscope. Automatically detect the positive and negative peaks in the signal. During the operation of the device, pay attention to the peak voltage displayed by the oscilloscope. At the same time, set the storage depth of the oscilloscope to record the signal peak over a longer period of time.

[0040] In another specific embodiment, the analysis obtains the collection environment impact assessment coefficient corresponding to the AC signal of each device. The specific analysis process is as follows: the electromagnetic interference intensity, signal fluctuation range and peak voltage size corresponding to the AC signal of each device are respectively recorded as , and ,in, Indicates the number corresponding to the AC signal of each device. , u is any integer greater than 2, substitute it into the calculation formula: The collection environment impact assessment coefficient corresponding to the AC signal of each device is obtained ,in, , , They are the standard electromagnetic interference intensity, standard signal fluctuation range, and standard peak voltage size corresponding to the set device AC signal. , , They are respectively the weight factor corresponding to the electromagnetic interference intensity of the AC signal of the set equipment, the weight factor corresponding to the signal fluctuation range, and the weight factor corresponding to the peak voltage size, and e represents a natural constant.

[0041] It should be noted that , , Both are greater than 0 and less than 1.

[0042] It should also be noted that through the summary of a large amount of research data and experimental data, the standard electromagnetic interference intensity, standard signal fluctuation range, and standard peak voltage size corresponding to the equipment AC signal are set according to professional institutions and research institutions. At the same time, based on the professional knowledge and research basis of experts in the field, and discussed and confirmed with industry organizations or professional institutions, the experts set the weight factors corresponding to the electromagnetic interference intensity of the equipment AC signal, the weight factors corresponding to the signal fluctuation range, and the weight factors corresponding to the peak voltage size according to their own experience and knowledge.

[0043] Related circuit parameter adjustment module: used to adjust and analyze the related circuit parameters corresponding to each device according to the collection environment impact assessment coefficient corresponding to the AC signal of each device.

[0044] In a specific embodiment, the relevant circuit parameters corresponding to each device are adjusted and analyzed, and the specific adjustment process is as follows: the acquisition environment impact assessment coefficient corresponding to the AC signal of each device is compared with the acquisition environment impact assessment coefficient interval corresponding to each relevant circuit parameter adjustment value in the database. If the acquisition environment impact assessment coefficient corresponding to the AC signal of a certain device is within the acquisition environment impact assessment coefficient interval corresponding to a certain relevant circuit parameter adjustment value in the database, then the relevant circuit parameter adjustment value in the database is used as the relevant circuit parameter adjustment value corresponding to the device. In this way, the relevant circuit parameters corresponding to each device are adjusted and analyzed.

[0045] In the embodiment of the present invention, the environmental impact data acquisition module is used to obtain the acquisition environment impact data such as the electromagnetic interference intensity, signal fluctuation range and peak voltage in detail, and the acquisition environment impact assessment coefficient corresponding to the AC signal of each device is analyzed to accurately understand the actual acquisition environment conditions of each device. The relevant circuit parameters corresponding to each device are adjusted and analyzed based on the assessment coefficient to ensure that the circuit parameters are highly adapted to the acquisition environment of the specific device. For example, in areas with strong electromagnetic interference, the anti-interference ability of the circuit can be strengthened in a targeted manner; for devices with large signal fluctuations, the circuit can be optimized to acquire signals more stably. This helps to improve the reliability and accuracy of the entire acquisition system in different complex industrial environments, and reduce signal acquisition errors or instabilities caused by environmental factors.

[0046] AC digital signal function judgment module: used to obtain the functional data corresponding to the AC signal of each device. The functional data includes the constant current source output current, feedback voltage, emitter voltage and acquisition voltage change rate, so as to analyze and obtain the functional evaluation value corresponding to the AC signal of each device, and then evaluate whether the AC signal function of each device is faulty.

[0047] In a specific embodiment, the functional data corresponding to the AC signal of each device is obtained, and the functional data includes the constant current source output current, feedback voltage, emitter voltage and acquisition voltage change rate. The specific acquisition process is as follows: B1. Connect the digital ammeter in series to the constant current source output circuit of each device, and directly read the value displayed by the ammeter to obtain the size of the constant current source output current.

[0048] B2. Connect the probe of the digital voltmeter to the output terminal of the feedback voltage of each device, and directly read the value displayed on the voltmeter to obtain the size of the feedback voltage.

[0049] B3. Use a voltmeter to directly connect the probe between the emitter of each device's transistor and the ground, and directly read the value displayed on the voltmeter to get the emitter voltage.

[0050] B4. Use the cursor function of the oscilloscope to measure the voltage change rate. After the voltage waveform is displayed on the oscilloscope of each device, enable the cursor function and place two cursors at two different positions on the waveform. The oscilloscope will display the time and voltage values ​​corresponding to the two cursor positions. By adjusting the cursor positions, calculate the voltage difference and time interval between different positions. Divide the voltage difference between different positions by the time interval to get the voltage change rate.

[0051] In another specific embodiment, the analysis obtains the function evaluation value corresponding to the AC signal of each device, and the specific analysis process is as follows: the constant current source output current, feedback voltage, emitter voltage and acquisition voltage change rate corresponding to the AC signal of each device are recorded as , , and ,in, Indicates the number corresponding to the AC signal of each device. , u is any integer greater than 2, substitute it into the calculation formula: The functional evaluation value corresponding to the AC signal of each device is obtained ,in, , , , They are the standard constant current source output current, standard feedback voltage, standard emitter voltage, and standard acquisition voltage change rate corresponding to the set device AC signal. , , , They are the weight factors corresponding to the output current of the AC signal constant current source of the set device, the weight factor corresponding to the feedback voltage, the weight factor corresponding to the emitter voltage, and the weight factor corresponding to the acquisition voltage change rate. , , , They are respectively the permitted constant current source output current difference, permitted feedback voltage difference, permitted emitter voltage difference, and permitted acquisition voltage change rate difference corresponding to the set device AC signal.

[0052] It should be noted that , , , Both are greater than 0 and less than 1.

[0053] It should also be noted that through the summary of a large amount of research data and experimental data. According to professional organizations and research institutions, the standard constant current source output current, standard feedback voltage, standard emitter voltage, and standard acquisition voltage change rate corresponding to the device AC signal are set. At the same time, based on the professional knowledge and research basis of experts in the field, and discussed and confirmed with industry organizations or professional institutions. Experts set the weight factors corresponding to the output current of the constant current source of the device AC signal, the weight factors corresponding to the feedback voltage, the weight factors corresponding to the emitter voltage, and the weight factors corresponding to the acquisition voltage change rate based on their own experience and knowledge.

[0054] In another specific embodiment, the evaluation of whether the AC signal function of each device is faulty is specifically analyzed as follows: the function evaluation value corresponding to the AC signal of each device is compared with the function evaluation value corresponding to the set standard device AC signal. If the function evaluation value corresponding to the AC signal of a certain device is greater than or equal to the function evaluation value corresponding to the set standard device AC signal, then it is evaluated that the AC signal function of the device is faulty. If the function evaluation value corresponding to the AC signal of a certain device is less than the function evaluation value corresponding to the set standard device AC signal, then it is evaluated that the AC signal function of the device is not faulty. In this way, it is evaluated whether the AC signal function of each device is faulty.

[0055] The embodiment of the present invention can obtain functional data including the output current of the constant current source, the feedback voltage, the emitter voltage and the acquisition voltage change rate, and analyze and obtain the functional evaluation value corresponding to the AC signal of each device, thereby realizing real-time monitoring of the AC signal function of each device. By comparing with the set standard functional evaluation value, it is possible to timely and accurately evaluate whether the AC signal function of each device is faulty. Once a fault is found, the fault type analysis module can quickly switch the AC signal of the faulty device to the fault detection channel for in-depth analysis, determine the specific fault type and issue an early warning prompt. This efficient fault diagnosis mechanism helps to shorten equipment downtime, improve production efficiency, and reduce maintenance costs. Because the fault point can be quickly located, maintenance personnel can perform repair work more targetedly.

[0056] Fault type analysis module: When a device's AC signal function fails, the device's AC signal is switched to the fault detection channel, and then the fault type corresponding to the device's AC signal is analyzed, and an early warning prompt is issued.

[0057] It should be noted that the fault types include open circuit fault, short circuit fault and signal amplitude fault.

[0058] In a specific embodiment, the AC signal of the device is switched to the fault detection channel, and the specific switching process is as follows: when the AC signal function of a certain device fails, after the switching circuit receives the fault trigger signal, the control circuit will process the signal, and the optocoupler relay will act as a switching switch. The fault trigger signal passes through a driving circuit to provide current and voltage to ensure that the optocoupler relay can operate normally. The switching switch switches the device AC signal from the normal transmission channel to the fault detection channel.

[0059] In another specific embodiment, the specific analysis process of analyzing the fault type corresponding to the AC signal fault of the device is as follows: comparing the functional evaluation value corresponding to the device with the functional evaluation value corresponding to each fault type in the database; if the functional evaluation value corresponding to the device is the same as the functional evaluation value corresponding to a certain fault type in the database, then the fault type in the database is recorded as the fault type corresponding to the AC signal fault of the device; in this way, the fault type corresponding to the AC signal fault of the device is analyzed.

[0060] In the embodiment of the present invention, the system adopts relatively standardized calculation formulas and comparison methods in various links such as obtaining environmental impact data, analyzing evaluation coefficients, adjusting circuit parameters, and judging equipment functions. For example, the evaluation coefficient is calculated by setting standard electromagnetic interference intensity, signal fluctuation range, peak voltage size and other parameters and corresponding weight factors; the function evaluation value is calculated by setting the standard constant current source output current, feedback voltage, transmitter voltage, acquisition voltage change rate and the corresponding weight factors. This standardized processing method makes the system have better standardization and repeatability, which is convenient for different operators to understand and operate, and is also conducive to the subsequent maintenance and upgrading of the system. At the same time, the system has certain scalability. According to actual needs, the data such as the acquisition environmental impact evaluation coefficient interval corresponding to each relevant circuit parameter adjustment value and the function evaluation value corresponding to each fault type can be continuously updated and expanded in the database to adapt to more types of equipment, more complex working conditions and newly emerging fault conditions, so as to ensure the effectiveness and applicability of the system in different application scenarios.

[0061] Embodiments of the present invention Figure 2 As shown, a method for collecting AC digital quantities based on PLC includes: Step 1, obtaining environmental impact data: obtaining the collected environmental impact data corresponding to the AC signal of each device in the programmable logic controller of the target enterprise, the environmental impact data including electromagnetic interference intensity, signal fluctuation range and peak voltage size, so as to analyze and obtain the collection environmental impact assessment coefficient corresponding to the AC signal of each device.

[0062] Step 2: Adjustment of relevant circuit parameters: According to the acquisition environmental impact assessment coefficient corresponding to the AC signal of each device, the relevant circuit parameters corresponding to each device are adjusted and analyzed.

[0063] Step 3. Determine the function of the AC digital signal: obtain the functional data corresponding to the AC signal of each device, the functional data includes the constant current source output current, feedback voltage, emitter voltage and acquisition voltage change rate, so as to analyze and obtain the functional evaluation value corresponding to the AC signal of each device, and then evaluate whether the AC signal function of each device is faulty.

[0064] Step 4: Analysis of fault type: When a device's AC signal function fails, the device's AC signal is switched to the fault detection channel, and then the fault type corresponding to the device's AC signal is analyzed, and an early warning prompt is issued.

[0065] The above contents are merely examples and explanations of the concept of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined in this specification, they shall all fall within the protection scope of the present invention.

Claims

1. A PLC-based AC digital quantity acquisition system, characterized in that: include: Environmental impact data acquisition module: used to obtain the collected environmental impact data corresponding to the AC signals of each device in the target enterprise's programmable logic controller. The environmental impact data includes electromagnetic interference intensity, signal fluctuation range and peak voltage size, so as to analyze and obtain the collected environmental impact assessment coefficient corresponding to the AC signals of each device; Related circuit parameter adjustment module: used to adjust and analyze the related circuit parameters corresponding to each device according to the collection environment impact assessment coefficient corresponding to the AC signal of each device; AC digital signal function judgment module: used to obtain the function data corresponding to the AC signal of each device, including the output current of the constant current source, feedback voltage, emitter voltage and acquisition voltage change rate, so as to analyze and obtain the function evaluation value corresponding to the AC signal of each device, and then evaluate whether the AC signal function of each device is faulty; Fault type analysis module: When a device's AC signal function fails, the device's AC signal is switched to the fault detection channel, and then the fault type corresponding to the device's AC signal is analyzed, and an early warning prompt is issued.

2. The PLC-based AC digital quantity acquisition system according to claim 1, characterized in that: The acquisition of the collected environmental impact data corresponding to the AC signals of each device in the programmable logic controller of the target enterprise is specifically carried out as follows: A1. Place the probe of the spectrum analyzer near the AC signal collection point of each device, set the appropriate frequency range and resolution bandwidth, measure multiple time periods during normal operation of the equipment, and record the electromagnetic interference intensity at different frequencies; A2. Connect the probe of the oscilloscope to the signal acquisition input terminal of the PLC of each device's AC signal, set the trigger mode of the oscilloscope to an appropriate mode, and continuously record the signal waveform for a period of time during the operation of the equipment, obtain the maximum and minimum values ​​of the waveform, and calculate the difference between the maximum and minimum values ​​of the waveform, and record the difference as the signal fluctuation range; A3. Use the peak detection function of the oscilloscope to capture the peak voltage. After connecting the oscilloscope probes of each device and setting the basic parameters, turn on the peak detection function of the oscilloscope. Automatically detect the positive and negative peaks in the signal. During the operation of the device, pay attention to the peak voltage displayed by the oscilloscope. At the same time, set the storage depth of the oscilloscope to record the signal peak over a longer period of time.

3. The PLC-based AC digital quantity acquisition system as claimed in claim 2, characterized in that: The analysis obtains the collection environment impact assessment coefficient corresponding to the AC signal of each device. The specific analysis process is as follows: The electromagnetic interference intensity, signal fluctuation range and peak voltage size corresponding to the AC signal of each device are recorded as , and ,in, Indicates the number corresponding to the AC signal of each device. , u is any integer greater than 2, substitute it into the calculation formula: The collection environment impact assessment coefficient corresponding to the AC signal of each device is obtained ,in, , , They are the standard electromagnetic interference intensity, standard signal fluctuation range, and standard peak voltage size corresponding to the set device AC signal. , , They are respectively the weight factor corresponding to the electromagnetic interference intensity of the AC signal of the set equipment, the weight factor corresponding to the signal fluctuation range, and the weight factor corresponding to the peak voltage size, and e represents a natural constant.

4. The PLC-based AC digital quantity acquisition system as claimed in claim 3, characterized in that: The relevant circuit parameters corresponding to each device are adjusted and analyzed, and the specific adjustment process is as follows: The acquisition environmental impact assessment coefficient corresponding to the AC signal of each device is compared with the acquisition environmental impact assessment coefficient interval corresponding to each relevant circuit parameter adjustment value in the database. If the acquisition environmental impact assessment coefficient corresponding to the AC signal of a certain device is within the acquisition environmental impact assessment coefficient interval corresponding to a relevant circuit parameter adjustment value in the database, the relevant circuit parameter adjustment value in the database will be used as the relevant circuit parameter adjustment value corresponding to the device. In this way, the relevant circuit parameters corresponding to each device are adjusted and analyzed.

5. The PLC-based AC digital quantity acquisition system as claimed in claim 4, characterized in that: The functional data corresponding to the AC signal of each device is obtained, and the functional data includes the output current of the constant current source, the feedback voltage, the emitter voltage and the acquisition voltage change rate. The specific acquisition process is as follows: B1. Connect the digital ammeter in series to the constant current source output circuit of each device, and directly read the value displayed by the ammeter to obtain the output current of the constant current source; B2. Connect the probe of the digital voltmeter to the output terminal of the feedback voltage of each device, and directly read the value displayed on the voltmeter to obtain the feedback voltage. B3. Use a voltmeter to directly connect the probe between the emitter and ground of each device's transistor, and directly read the value displayed on the voltmeter to get the emitter voltage. B4. Use the cursor function of the oscilloscope to measure the voltage change rate. After the voltage waveform is displayed on the oscilloscope of each device, enable the cursor function and place two cursors at two different positions on the waveform. The oscilloscope will display the time and voltage values ​​corresponding to the two cursor positions. By adjusting the cursor positions, calculate the voltage difference and time interval between different positions. Divide the voltage difference between different positions by the time interval to get the voltage change rate.

6. The PLC-based AC digital quantity acquisition system as claimed in claim 5, characterized in that: The analysis obtains the functional evaluation value corresponding to the AC signal of each device. The specific analysis process is as follows: The constant current source output current, feedback voltage, emitter voltage and acquisition voltage change rate corresponding to the AC signal of each device are recorded as , , and ,in, Indicates the number corresponding to the AC signal of each device. , u is any integer greater than 2, substitute it into the calculation formula: The functional evaluation value corresponding to the AC signal of each device is obtained ,in, , , , They are the standard constant current source output current, standard feedback voltage, standard emitter voltage, and standard acquisition voltage change rate corresponding to the set device AC signal. , , , They are the weight factors corresponding to the output current of the AC signal constant current source of the set device, the weight factor corresponding to the feedback voltage, the weight factor corresponding to the emitter voltage, and the weight factor corresponding to the acquisition voltage change rate. , , , They are respectively the permitted constant current source output current difference, permitted feedback voltage difference, permitted emitter voltage difference, and permitted acquisition voltage change rate difference corresponding to the set device AC signal.

7. The PLC-based AC digital quantity acquisition system according to claim 6, characterized in that: The specific analysis process of evaluating whether the AC signal function of each device is faulty is as follows: The function evaluation value corresponding to the AC signal of each device is compared with the function evaluation value corresponding to the set standard device AC signal. If the function evaluation value corresponding to the AC signal of a certain device is greater than or equal to the function evaluation value corresponding to the set standard device AC signal, it is evaluated that the AC signal function of the device is faulty. If the function evaluation value corresponding to the AC signal of a certain device is less than the function evaluation value corresponding to the set standard device AC signal, it is evaluated that the AC signal function of the device is not faulty. In this way, it is evaluated whether the AC signal function of each device is faulty.

8. The PLC-based AC digital quantity acquisition system according to claim 7, characterized in that: The AC signal of the device is switched to the fault detection channel. The specific switching process is as follows: When the AC signal function of a device fails, after the switching circuit receives the fault trigger signal, the control circuit will process the signal. The optocoupler relay acts as a switching switch. The fault trigger signal passes through a drive circuit to provide current and voltage to ensure that the optocoupler relay can operate normally. The switching switch switches the device AC signal from the normal transmission channel to the fault detection channel.

9. The PLC-based AC digital quantity acquisition system according to claim 8, characterized in that: The specific analysis process of analyzing the fault type corresponding to the AC signal fault of the device is as follows: The functional evaluation value corresponding to the device is compared with the functional evaluation values ​​corresponding to each fault type in the database. If the functional evaluation value corresponding to the device is the same as the functional evaluation value corresponding to a certain fault type in the database, the fault type in the database is recorded as the fault type corresponding to the AC signal fault of the device. In this way, the fault type corresponding to the AC signal fault of the device is analyzed.

10. A PLC-based AC digital quantity acquisition method for executing the PLC-based AC digital quantity acquisition system according to any one of claims 1 to 9, characterized in that: include: Step 1: Obtaining environmental impact data: Obtain the collected environmental impact data corresponding to the AC signal of each device in the target enterprise's programmable logic controller. The environmental impact data includes electromagnetic interference intensity, signal fluctuation range and peak voltage, so as to analyze and obtain the collected environmental impact assessment coefficient corresponding to the AC signal of each device; Step 2: Adjustment of relevant circuit parameters: According to the collection environment impact assessment coefficient corresponding to the AC signal of each device, the relevant circuit parameters corresponding to each device are adjusted and analyzed; Step 3: Determine the function of the AC digital signal: obtain the function data corresponding to the AC signal of each device, including the output current of the constant current source, the feedback voltage, the emitter voltage and the acquisition voltage change rate, so as to analyze and obtain the function evaluation value corresponding to the AC signal of each device, and then evaluate whether the AC signal function of each device is faulty; Step 4: Analysis of fault type: When a device's AC signal function fails, the device's AC signal is switched to the fault detection channel, and then the fault type corresponding to the device's AC signal is analyzed, and an early warning prompt is issued.

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