A PLC / DCS remote I / O network fault detection device and method

Abstract

This application provides a PLC / DCS remote I / O network fault detection device and method. The device includes a PLC / DCS master station and a remote I / O station. The remote I / O station includes an analog output module and an analog input module. The analog output module includes multiple first pins and an unused target first pin. The analog input module includes multiple second pins and an unused target second pin. Each target first pin is connected to a corresponding target second pin to form an analog signal loop. The PLC / DCS master station outputs a generated analog test signal to the target first pin. After the analog test signal reaches the target first pin, it is transmitted through the target first pin and the analog signal loop to the target second pin, forming a retrieved analog signal. The PLC / DCS master station also reads the retrieved analog signal and performs fault detection based on the analog test signal and the retrieved analog signal.

Description

Technical Field

[0001] This application relates to the field of fault detection technology, and in particular to a PLC / DCS remote IO network fault detection device and method. Background Technology

[0002] In the control systems of critical infrastructure and equipment, PLCs (Programmable Logic Controllers) and DCSs (Distributed Control Systems) are core devices. Remote / distributed I / O networks, as an important component of PLC / DCS control systems, rely on industrial Ethernet or fieldbus for data transmission. Communication anomalies can lead to signal loss, system malfunctions, equipment shutdowns, and even safety incidents. Therefore, the control system's CPU needs to have the ability to monitor the remote I / O network communication status in real time and promptly initiate emergency measures upon detecting anomalies to ensure the safe and stable operation of the system.

[0003] Currently, remote I / O network fault detection in PLC / DCS products, both domestically and internationally, primarily relies on internal system network status information for judgment. The detection method is as follows: the control system's CPU analyzes communication interaction information between the network processor and network adapter of the remote I / O network. By detecting the internal status words of the system, it determines whether remote I / O communication is normal. If an abnormal status word is detected, a network fault emergency procedure is activated to prevent system malfunction or accidental operation. This method has the following drawbacks: Lack of transparency: The network status judgment mechanism is written by the controller's underlying operating system, which users cannot directly participate in or adjust; its reliability can only be verified through application testing. Risk of false alarms or missed alarms: Relying solely on system status word detection may lead to missed alarms due to inaccurate detection, failing to detect network anomalies in a timely manner, thus increasing the risk of accidents. Lack of proactive detection mechanism: Existing methods are based solely on passively reading status information and cannot proactively verify the actual communication capabilities of the network, resulting in delays and limitations.

[0004] Therefore, there is an urgent need for a device that uses an active detection method based on physical signals to improve the accuracy and reliability of fault detection in PLC / DCS remote I / O network communication. Summary of the Invention

[0005] In view of this, this application provides a PLC / DCS remote IO network fault detection device and method, which improves the accuracy and reliability of PLC / DCS remote IO network communication fault detection through active detection based on physical signals.

[0006] Specifically, this application is implemented through the following technical solution:

[0007] This application provides a PLC / DCS remote I / O network fault detection device, characterized in that the PLC / DCS remote I / O network fault detection device includes a PLC / DCS master station and a remote I / O station, the PLC / DCS master station being connected to the remote I / O station; the remote I / O station includes an analog output module and an analog input module, the analog output module including a plurality of first pins, among which there is an unoccupied target first pin; the analog input module including a plurality of second pins, among which there is an unoccupied target second pin; each target first pin is connected to a corresponding target second pin to form an analog signal loop;

[0008] The PLC / DCS master station is used to generate analog test signals and output the analog test signals to the target first pin in the analog output module;

[0009] After the simulated test signal reaches the first pin of the target, it is transmitted through the simulated signal loop to the second pin of the target in the simulated input module, which corresponds to the first pin of the target, to form a recovered simulated signal;

[0010] The PLC / DCS master station is also used to read the recovery simulation signal and perform fault detection based on the simulation test signal and the recovery simulation signal.

[0011] A second aspect of this application provides a method for detecting faults in a PLC / DCS remote I / O network, the method being applied to a PLC / DCS remote I / O network fault detection device as described in any one of the claims of the first aspect of this application, the method comprising:

[0012] Identify the target first pin in the first pin, and identify the target second pin in the second pin; the target first pin and the target second pin constitute an analog signal loop;

[0013] The PLC / DCS master station generates a simulated test signal and transmits the simulated test signal to the first pin of the target.

[0014] The simulated test signal passes through the first pin of the target and the simulated signal loop, and then reaches the second pin of the target to form a recovered simulated signal.

[0015] The PLC / DCS master station reads the recovery simulation signal and performs fault detection based on the simulation test signal and the recovery simulation signal.

[0016] The PLC / DCS remote I / O network fault detection device and method provided in this application constructs a physical signal detection mechanism based on analog signal loops. This hardware fault detection enables software fault diagnosis, without interfering with the inherent functions of remote I / O, requiring no additional hardware structure or changes to the original software flow. It directly achieves reliable signal detection, thus enabling accurate fault diagnosis. Compared to traditional methods relying on network status words or communication protocol feedback, this method offers higher detection accuracy and reliability. By utilizing unused pins between analog output and input modules to form an analog signal loop, the PLC / DCS master station can directly send and receive analog test signals. This allows for the determination of remote I / O network normality through physical-level signal transmission, bypassing the traditional network status detection mechanism at the PLC / DCS master station level. It is unaffected by software-level faults or communication protocol anomalies, avoiding safety risks caused by false or missed network status word reports. Furthermore, this application can accurately detect different types of faults. First, if the PLC / DCS master station does not receive the recovered analog signal, it indicates that there may be a physical disconnection in the analog signal loop, a serious network failure, or an abnormality in the remote I / O module, thus enabling rapid identification of serious fault conditions. Second, by comparing the waveforms of the recovered analog signal and the test analog signal, the fault condition of the recovered analog signal can be further determined. Furthermore, the detection method of this application also has stronger system transparency and controllability. Because it does not rely on the built-in detection mechanism of the PLC / DCS master station's underlying operating system, users can freely adjust the transmission cycle, timeout time, and detection strategy, making this method applicable to PLC / DCS systems of different brands and architectures, and in particular enhancing the reliability of domestically developed and controllable PLC / DCS systems. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the PLC / DCS remote IO network fault detection device provided in Embodiment 1 of this application;

[0018] Figure 2 This is a flowchart of the PLC / DCS remote IO network fault detection method provided in Embodiment 2 of this application. Detailed Implementation

[0019] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0020] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used herein are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0021] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0022] The following specific embodiments are given to illustrate the technical solution of this application in detail.

[0023] Figure 1 This is a schematic diagram of the PLC / DCS remote I / O network fault detection device provided in Embodiment 1 of this application. Please refer to... Figure 1 The PLC / DCS remote I / O network fault detection device provided in this embodiment includes a PLC / DCS master station and a remote I / O station, with the PLC / DCS master station connected to the remote I / O station. The remote I / O station includes an analog output module and an analog input module. The analog output module includes multiple first pins, among which there is an unoccupied target first pin. The analog input module includes multiple second pins, among which there is an unoccupied target second pin. Each target first pin is connected to a corresponding target second pin to form an analog signal loop.

[0024] The PLC / DCS master station is used to generate analog test signals and output the analog test signals to the target first pin in the analog output module;

[0025] After the simulated test signal reaches the first pin of the target, it is transmitted through the simulated signal loop to the second pin of the target in the simulated input module, which corresponds to the first pin of the target, to form a recovered simulated signal;

[0026] The PLC / DCS master station is also used to read the recovery simulation signal and perform fault detection based on the simulation test signal and the recovery simulation signal.

[0027] For details, please refer to Figure 1The PLC / DCS remote I / O network fault detection device includes a PLC / DCS master station and remote I / O stations. The PLC / DCS master station and the remote I / O stations are connected via industrial Ethernet or an industrial bus of any protocol.

[0028] It's important to note that while PLC master stations and DCS master stations differ in their overall architecture and application scenarios, they share a consistent network fault detection mechanism for remote I / O stations: both determine the communication link's functionality by sending test signals, receiving feedback signals, and comparing and analyzing them. The main difference lies in the control logic of signal processing: PLC master stations are typically used in discrete control systems, focusing more on real-time logic judgment and output control of digital signals, while DCS master stations are more commonly used in process control, prioritizing continuous adjustment of analog signals and process stability. Therefore, there may be differences in the methods and emphasis used to send test signals. For example, DCS master stations tend to use continuous analog signal waveforms for fault analysis, while PLC master stations prefer pulsed digital signals for testing. However, the overall detection process and principle are consistent; therefore, this article will use the PLC master station as an example for explanation.

[0029] The PLC master station is the core control unit, responsible for managing the operation of the entire PLC control system. The PLC master station is responsible for generating and sending analog test signals to detect the communication status of remote I / O stations, reading the returned analog signals, determining whether the remote I / O station network is normal, and executing corresponding fault handling strategies when network anomalies are detected.

[0030] Furthermore, the PLC master station consists of multiple modules, including a CPU module, a memory module, a power supply module, an I / O interface module, a communication module, a clock module, and a fault detection and diagnosis module. The CPU module is responsible for executing the PLC program, processing input signals, and generating corresponding control outputs. Internally, the CPU module contains an arithmetic unit, memory, a clock system, and an input / output management unit. The memory module stores the PLC program, system parameters, variable data, and historical records. The memory module includes RAM (Random Access Memory) for runtime data storage and ROM / Flash (Read-Only Memory) for storing PLC firmware and user programs. The power supply module provides a stable operating voltage to all modules within the PLC master station. The I / O interface module integrates digital input, digital output, analog input, and analog output interfaces for signal interaction with external devices (such as sensors and actuators). The communication module handles data communication between the PLC master station and remote I / O stations, host computers, or other control devices. The communication module supports protocols such as Industrial Ethernet, PROFIBUS, Modbus, CAN, and RS-485. The clock module provides the system clock for functions such as time synchronization, logging, and timing control. The fault detection and diagnosis module is used to detect the system's operating status, record fault information, and provide alarm and diagnostic functions.

[0031] The remote I / O station is an I / O expansion unit used to expand the input and output capabilities of the PLC master station, supporting the acquisition and execution of remote signals. The remote I / O station includes multiple functional modules, primarily analog output and analog input modules for data transmission and status feedback. Each module has multiple hardware pins for signal transmission, arranged in a layout that can be independently wired, supporting flexible signal access and transmission. Some pins are idle in practical applications. The analog output module receives control signals from the PLC master station and outputs signals externally. It has multiple first pins that output analog waveform signals. During network fault detection, an unused first pin in the remote I / O station is selected as the target first pin, through which analog test signals are sent. The analog input module receives external signals and uploads them to the PLC master station. It has multiple second pins for receiving analog test signals. During network fault detection, an unused second pin in the remote I / O station is selected as the target second pin to receive analog test signals emitted from the target first pin. The analog signal loop refers to the connection between the first and second pins of the target, used to ensure that the analog test signal can be transmitted and fed back to the PLC master station. When the analog test signal can be returned to the PLC master station normally, it indicates that the communication network status of the remote I / O station is normal. If the PLC master station fails to receive the analog test signal, it indicates that there may be a communication anomaly (such as a broken line, module failure, etc.).

[0032] Based on the above description, the PLC master station and remote I / O stations are typically independent physical devices. The PLC master station, as the system control core, integrates a CPU, power supply module, and communication interface, and can be configured with local input / output modules as needed. The remote I / O station, as an extension unit of the PLC system, typically communicates with the PLC master station via industrial communication protocols. Each remote I / O station can internally connect multiple functional modules, such as digital input modules, digital output modules, analog input modules, and analog output modules. Each type of module consists of multiple pins of the same type; for example, an analog input module has several analog input pins, and an analog output module has several analog output pins. These modules are connected to the remote I / O backplane via a unified bus structure, forming an integrated, modular device unit.

[0033] It should be noted that analog input and output modules typically contain multiple pins (terminals) designed to accommodate industrial control needs of varying scales and complexities. Each pin can be used to connect different sensors, actuators, or other external devices, enabling multi-channel data acquisition and signal control. In practical applications, some pins may already be occupied for normal input / output control tasks, such as driving motors or monitoring sensor status. Other pins may be unused and can be used as target pins for additional functional expansion, such as remote I / O network fault detection. By selecting unused target pins (target first pin as an output pin and target pin second pin as an input pin), the detection signal generated by the PLC is sent to target pin first in the remote I / O system. Based on the modified connectivity, the signal is directly fed back to target pin second as an input signal, which is then directly fed back to the PLC. Therefore, an independent signal loop for fault detection can be established without affecting the original control tasks. This not only maximizes the use of hardware resources but also improves the flexibility of detection, enabling real-time monitoring and anomaly diagnosis of remote I / O networks without the need for additional hardware.

[0034] Furthermore, the PLC master station uses the PLC timer or system function to generate an analog test signal based on a set transmission cycle (periodic triggering) and sends it to a target first pin in the analog output module. The analog test signal is output from the target first pin and transmitted to the target second pin in the analog input module through the established analog signal loop. The PLC master station reads the signal status of the target second pin in the analog input module to obtain the received analog signal. The PLC master station performs fault detection based on the read received analog signal and transmission cycle to determine whether the communication is normal. If the received analog signal returns according to the set cycle, and the waveform of the received analog signal is close to that of the analog test signal, it indicates that the remote I / O network communication is normal. If no received analog signal is received, it may be due to a network communication failure, a broken wiring loop, or a failure of the remote I / O module. If the received analog signal is delayed or the cycle is mismatched, it may be due to communication congestion, data loss, or abnormal synchronization between the PLC and the remote I / O station. If the PLC master station detects a communication abnormality, it can take the following emergency measures: Alarm: Trigger a warning signal to prompt maintenance personnel to check the remote I / O station connection. Switch to Safe Mode: If the PLC master station detects a continuous communication anomaly, it can enter safe mode and execute preset fault handling logic (such as shutdown or switching to a redundant system). Record Fault Log: Stores data such as fault time and signal loss details for later analysis.

[0035] Optionally, the PLC / DCS master station is further configured to read the recovered analog signal and perform fault detection based on the analog test signal and the recovered analog signal, including: obtaining the time delay between the transmitted pulse signal and the recovered pulse signal as a time difference; determining whether there is a time delay anomaly based on the comparison result of the time difference with a preset time threshold, and identifying the corresponding time delay type fault; performing waveform analysis on the recovered pulse signal, extracting the pulse shape features corresponding to the transmitted pulse signal, and calculating the pulse shape deviation value; determining whether there is a signal distortion anomaly based on the comparison result of the pulse shape deviation value with a preset shape deviation threshold, and identifying the corresponding waveform type fault; and comprehensively determining the fault category based on the joint analysis result of the time difference value and the pulse shape deviation value.

[0036] In practice, the PLC master station outputs an analog test signal to the first pin of the target device during each transmission cycle while recording the current timestamp. When the received analog signal is received, the received timestamp is recorded. The time difference between transmission and reception is obtained by subtracting the received timestamp from the current timestamp. The calculated time difference is compared with a preset time delay threshold. If it exceeds the threshold, a time delay anomaly is identified and marked as a time delay fault. Further, the PLC master station samples the waveform of the received analog signal, extracting key characteristic parameters such as rise time, fall time, peak amplitude, and pulse width. This is compared with the waveform characteristics of the original analog test signal to calculate the pulse shape deviation. The calculated pulse shape deviation is compared with a set waveform shape deviation threshold. If the deviation exceeds the threshold, a signal distortion anomaly is identified and marked as a waveform fault. Finally, the time difference judgment result and the pulse shape deviation judgment result are jointly analyzed to determine the final fault category based on different combinations (e.g., simultaneous anomalies, or only a single anomaly).

[0037] Optionally, the PLC master station reads the analog signal received by the second pin of the target device and forms a recovered analog signal. The recovered analog signal is sampled in real time to obtain waveform curves or characteristic values ​​(such as amplitude, frequency, rising edge, etc.). The PLC master station compares the waveform corresponding to the analog test signal with the waveform corresponding to the recovered analog signal and calculates the waveform difference (including amplitude error, waveform distortion, etc.). Based on the waveform difference, the corresponding fault category is determined; different waveform differences correspond to different fault categories. If the waveform difference is within the allowable threshold range, communication is considered normal; if the waveform difference exceeds the preset threshold, the specific fault type is identified according to different difference patterns. For example, abnormal amplitude is identified as signal attenuation or voltage clamping fault; waveform distortion is identified as internal module interference or cable electromagnetic interference.

[0038] Optionally, the remote I / O station includes a digital output module and a digital input module. The digital output module includes multiple third pins, among which there is an unused target third pin. The digital input module includes multiple fourth pins, among which there is an unused target fourth pin. Each target third pin is connected to a corresponding target fourth pin to form a wiring loop. The PLC / DCS master station is used to generate a transmit pulse signal and output the transmit pulse signal to the target third pin in the digital output module. After the transmit pulse signal reaches the target third pin, it is transmitted through the wiring loop to the target fourth pin in the digital input module corresponding to the target third pin, forming a receive pulse signal.

[0039] It should be noted that in fault detection of PLC remote I / O networks, either digital input / output modules or analog input / output modules can be used for signal transmission and detection. The basic detection principles of both are similar. Whether using digital or analog signals, the core detection mechanism involves checking the integrity, timing characteristics, and periodicity of the received signal after it is sent, thereby determining whether there is a communication anomaly in the remote I / O network. The main difference lies in the signal type. Digital input / output modules are primarily used to send and receive pulse signals. The PLC master station sends a specific pulse signal to the target output pin, which is then transmitted to the target input pin through a wiring loop. The PLC master station determines whether the network status is normal by detecting the presence, transmission time, and periodic stability of the received pulse signal. Analog input / output modules are primarily used to send and receive analog waveform signals (such as sine waves, sawtooth waves, or voltage / current signals with specific amplitude variations).

[0040] Optionally, after the recovery pulse signal is generated, if the PLC / DCS master station does not read the recovery analog signal, a first fault type is determined; if the PLC / DCS master station reads the recovery analog signal, the reading time is determined, and a first fault detection is performed based on a comparison between the reading time and the timeout time; the PLC / DCS master station determines the reading period of the recovery analog signal, calculates the difference between the reading period and the sending period, and performs a second fault detection based on the difference.

[0041] In practice, the PLC master station reads the signal status of the target's third pin to determine whether the received pulse signal has been successfully received. If no received pulse signal is read, it is directly identified as the first fault type (which may be a line disconnection, remote I / O station failure, or communication failure). In the first fault detection, if the received pulse signal is successfully received, the reading time is recorded. The reading time is compared with the set timeout. If the reading time exceeds the timeout, it indicates severe communication delay or signal loss, and the second fault type is determined (such as abnormal signal transmission). If the timeout does not exceed the timeout, the next step of detection is performed, entering the second fault detection. The reading time of multiple consecutive received pulse signals is recorded, and the reading cycle is calculated. The difference between the reading cycle and the sending cycle is calculated to determine whether there is a periodic anomaly: if the difference exceeds the set threshold, it indicates that there is jitter, delay, or loss in signal transmission, and the third fault type is determined (such as network instability or excessive load). If the difference is within the normal range, communication is determined to be normal.

[0042] Optionally, after fault detection based on the simulated test signal and the recovered simulated signal, if a fault exists, the PLC / DCS master station is further used to determine the untested idle pin pairs among the target first pin and target second pin that have formed a simulated signal loop, select any idle pin pair as the pin pair used for fault detection, and generate the simulated test signal again.

[0043] It should be noted that during remote I / O network fault detection, there is a possibility that signal transmission abnormalities may occur due to faults in the pins themselves or in the wiring circuits. This could lead to false tests and misjudgments of a communication network fault. To avoid incorrect judgments due to a single test, this application designs a retesting mechanism. When an anomaly is detected during the initial test, the PLC master station will select another set of unused pin pairs for repeated testing. This redundancy verification effectively eliminates false judgments caused by local hardware faults, improving the accuracy of fault detection and the reliability of the system.

[0044] In practice, after each fault detection, the PLC master station tags the pin pairs used in each fault detection (e.g., "normal" or "abnormal") based on the read status of the recovered analog signals, and determines whether a new pin pair needs to be selected for retry. If a pair of pins does not receive a recovered analog signal, the PLC master station does not immediately classify it as a remote I / O station network communication anomaly. Instead, it first determines whether the currently used pin pair is experiencing an anomaly for the first time. If so, it selects another pair from the idle pin pairs for redundancy detection. Based on the recorded idle pin status, the PLC master station reselects a target first pin and a target second pin from the unused target first pin and target second pin, forming a new detection channel (analog signal loop). The newly selected target first pin begins receiving the analog test signal sent by the PLC master station, and the new target second pin is used to read the recovered analog signal for a second detection.

[0045] The PLC remote I / O network fault detection device provided in this embodiment constructs a physical signal detection mechanism based on analog signal loops. It uses hardware fault detection to determine software faults, without interfering with the inherent functions of remote I / O, without adding other hardware structures, and without changing the original software flow of remote I / O. It directly achieves reliable signal detection, thus enabling accurate fault diagnosis. Compared to traditional methods relying on network status words or communication protocol feedback, it has higher detection accuracy and reliability. By utilizing unused pins between the analog output and analog input modules to form an analog signal loop, the PLC / DCS master station can directly send and receive analog test signals. This allows for the determination of whether the remote I / O network is normal based on the physical layer signal transmission status, bypassing the traditional network status detection mechanism at the PLC / DCS master station level. It is unaffected by software-level faults or communication protocol anomalies, avoiding security risks caused by false or missed network status word reports. Furthermore, this application can accurately detect different types of faults. First, if the PLC / DCS master station does not receive the received analog signal, it indicates that the analog signal loop may have a physical disconnection, a serious network fault, or an abnormal remote I / O module, thus enabling rapid identification of serious fault conditions. Secondly, by comparing the waveforms of the recovered analog signal and the test analog signal, the fault condition of the recovered analog signal can be further determined. Furthermore, the detection method of this application has greater system transparency and controllability. Since it does not rely on the built-in detection mechanism of the PLC / DCS master station's underlying operating system, users can freely adjust the transmission cycle, timeout time, and detection strategy, making this method applicable to PLC systems of different brands and architectures, and in particular enhancing the reliability of domestically developed and controllable PLC / DCS systems.

[0046] Corresponding to the aforementioned embodiment of a PLC / DCS remote IO network fault detection device, this application also provides an embodiment of a PLC / DCS remote IO network fault detection method.

[0047] Figure 2 This is a flowchart illustrating the PLC / DCS remote I / O network fault detection method provided in Embodiment 2 of this application. Please refer to... Figure 2 The method provided in this embodiment is applied to the PLC / DCS remote IO network fault detection device according to any one of the first aspects of this application, and the method includes:

[0048] S201. Determine the target first pin in the first pin and the target second pin in the second pin; the target first pin and the target second pin constitute an analog signal loop.

[0049] Specifically, the target first pin is the first pin in an idle state, and the target second pin is the second pin in an idle state. Each target first pin and its corresponding target second pin form a wiring loop.

[0050] In specific implementation, determining the target first pin in the first pin and the target second pin in the second pin includes: acquiring the output pins and input pins in the idle state of the remote I / O station; filtering pin pairs that meet the connection conditions based on the signal type and voltage level of the output pins and the input pins to form a candidate pin group; the candidate pin group includes a pair of matched output pins and input pins; filtering the candidate pin group based on the distance between the output pins and the input pins in the candidate pin group to obtain a target pin group; and determining the target first pin and the target second pin based on the target pin group.

[0051] Specifically, the PLC master station obtains a list of currently unused pins through the management functions or status query commands of the remote I / O station. This list includes output pins and input pins (output pins are unused ports in the digital output module, which can be used to send signals; input pins are unused ports in the digital input module, which can be used to receive signals). Further, after obtaining all available pins, the PLC master station performs matching on the obtained free pins, including matching based on signal type and voltage level. First, signal type matching is performed to ensure that the signal types of the output and input pins are the same. For example, if the output pin is a digital signal (high or low level), then the input pin should also support digital signals. If the output pin is an analog signal (voltage or current change), then the input pin should be able to receive the corresponding analog signal. Next, voltage level matching is performed to ensure that the voltage or current range of the output pin is compatible with the input pin. For example, if the output pin is a 24V signal, then the input pin must be able to withstand 24V; otherwise, the input port may be damaged due to excessive voltage, or the signal may not be detected correctly due to insufficient voltage. After matching in both aspects, a preliminary candidate pin group is obtained, containing several pairs of output and input pins that can be correctly connected. Following the candidate pin group, the PLC master station further analyzes the distance between each pair of output and input pins, eliminating those pairs that are too far apart and may affect signal transmission, ultimately leaving the optimized target pin group. Since the pins of the remote I / O station may be distributed across different modules, the distance between some pins may be relatively large. Long-distance signal transmission is susceptible to interference and may lead to signal attenuation or delay. Selecting pin pairs with shorter distances can reduce signal attenuation and improve signal stability and transmission reliability. From the final target pin group, the optimal pair of pins is selected as the first target pin (output) and the second target pin (input).

[0052] The method provided in this embodiment determines target pins based on screening available pins, matching signal types and voltage levels, and considering physical distance, thereby forming a wiring loop. This optimizes the pin selection process while ensuring signal matching, improving signal transmission quality, reducing wiring costs, and enhancing system flexibility and fault tolerance, thus making PLC remote I / O network fault detection more efficient and reliable. First, this application fully utilizes available resources within the remote I / O station, avoiding resource waste caused by fixed use of certain pins, and improving system flexibility and adaptability. Second, by screening signal types and voltage levels, it ensures that the selected input and output pins are correctly matched, avoiding false detections or signal distortion caused by signal incompatibility, thereby improving the reliability of fault detection. Furthermore, by considering the physical distance between pins to further screen target pin groups, it effectively reduces signal attenuation, interference, and delay problems caused by long-distance wiring, improving the system's signal transmission quality and detection accuracy. Especially in industrial environments, long-distance wiring can not only lead to electromagnetic interference but also increase wiring costs and maintenance difficulty; therefore, selecting pin pairs with closer distances helps optimize the system's structural layout. This method of dynamically determining target pins is more flexible and adaptable than traditional fixed-pin detection methods. Traditional methods typically pre-define fixed detection pins, and if a pin fails or is occupied, the system may fail to continue operating normally. This method, however, can dynamically select the optimal pin pair based on the actual situation. Even if some pins are occupied by other tasks, backup pin pairs can still be selected for fault detection, improving system stability and fault tolerance.

[0053] S202, the PLC / DCS master station generates a simulated test signal and transmits the simulated test signal to the first pin of the target.

[0054] Specifically, the simulated test signal has a transmission period, which is determined according to the specific application scenario.

[0055] In specific implementation, the PLC / DCS master station generates simulated test signals, including: identifying the application scenario of the PLC / DCS master station; determining the application industry requirements based on the application scenario; determining the transmission cycle range according to the application scenario and the application industry requirements; determining the transmission cycle value based on historical fault data within the transmission cycle range; setting transmission cycle parameters based on the transmission cycle value, and continuously generating simulated test signals under the transmission cycle parameters; the PLC / DCS master station monitors the network status of the remote IO station in real time, and adjusts the transmission cycle value based on the network status.

[0056] Specifically, the PLC master station first identifies the current application scenario, such as industrial automation, process control, building management, and energy monitoring. By reading system configuration parameters or user-defined operating modes, it determines the PLC's current operating environment. In different application scenarios, the PLC's network communication requirements, response time, and fault tolerance vary. After identifying the application scenario, the PLC master station further determines the corresponding industry standards or technical requirements. For example, in the power industry, remote I / O communication typically requires high real-time performance and redundancy. In the petrochemical industry, high security requirements necessitate potentially higher fault detection frequencies. In general manufacturing, efficiency and balanced communication load may be more important. The PLC master station extracts relevant industry requirements from its built-in industry standard database, or allows users to manually set key parameters, to ensure the reasonableness of the transmission cycle. Based on the application scenario and industry requirements, the PLC master station calculates a reasonable transmission cycle range. The transmission cycle typically has a minimum and maximum value to ensure that neither too short a cycle leads to excessive communication load, nor too long a cycle affects the timeliness of fault detection. For example, in scenarios with high real-time requirements, the transmission cycle range might be 10ms-50ms, while in ordinary industrial control, it might be 100ms-500ms. Within this range, the PLC master station further optimizes the specific transmission cycle value using historical fault data. By analyzing historical data, including the frequency of communication faults, fault duration, and false alarm rate, a suitable transmission cycle value is selected. For example, if a 50ms transmission cycle has a lower false alarm rate and a higher detected fault rate in past monitoring, then 50ms might be chosen as the current transmission cycle value. After determining the transmission cycle value, the PLC master station writes this value into the system parameters and continuously generates simulated test signals within the set transmission cycle. The PLC master station sends simulated test signals to the target's first pin at set time intervals, ensuring that the signal can regularly enter the detection loop of the remote I / O station. This process continues, forming a stable detection signal stream for subsequent fault monitoring. During operation, the PLC master station monitors the network communication status of the remote I / O station in real time and adjusts the transmission cycle value based on the network conditions. When network conditions are poor (e.g., signal loss, increased latency), the PLC master station may shorten the transmission cycle to increase the detection frequency and thus detect network anomalies more quickly. When network conditions are stable, the PLC master station may appropriately extend the transmission cycle to reduce system load and lower the false alarm rate.

[0057] The method provided in this embodiment, which dynamically adjusts the transmission cycle setting based on the application scenario, can significantly improve the adaptability, accuracy, and reliability of PLC remote I / O network fault detection. First, by identifying the application scenario of the PLC master station and combining it with industry requirements, the transmission cycle range is determined. This ensures that the initial setting of the transmission cycle conforms to the operating standards and application needs of the specific industry, avoiding false alarms or missed alarms caused by unreasonable fixed cycle settings. Different industrial control scenarios have different real-time requirements for network fault detection. For example, high-speed automated production lines may require shorter detection cycles, while environmental monitoring systems may have more lenient cycle requirements. This approach can flexibly adapt to different needs, improving system applicability. Second, within the transmission cycle range, the specific transmission cycle value is determined by combining historical fault data, enabling the system to optimize the detection frequency based on past fault patterns and trends. This method can improve the targeting and effectiveness of fault detection while reducing resource consumption. For example, in a stable operating system with a low failure rate, the transmission cycle can be appropriately extended to reduce system load; while in an environment with frequent recent faults, shortening the transmission cycle can improve the timeliness of detection, thereby discovering potential problems as early as possible and preventing accidents. Furthermore, the PLC master station monitors the network status of remote I / O stations in real time and adjusts the transmission cycle value based on the network status, enabling the system to dynamically optimize the detection strategy in complex environments. For example, when network fluctuations or increased data transmission latency are detected, the PLC can automatically shorten the transmission cycle to monitor the network status more intensively, ensuring stable system operation; conversely, when the network status is stable, the cycle can be appropriately relaxed to reduce unnecessary signal transmissions and optimize system resource utilization. This adaptive adjustment mechanism allows the system to achieve optimal detection results under different operating conditions, while reducing system load and improving overall energy efficiency.

[0058] S203. The simulated test signal passes through the first pin of the target and the simulated signal loop, and then reaches the second pin of the target to form a recovered simulated signal.

[0059] In practice, the PLC master station outputs an analog test signal to the target first pin of the analog output module according to a set transmission cycle. The analog test signal is transmitted from the target first pin through an analog signal loop, along a pre-connected physical line to the analog input module of the remote I / O station. When the analog test signal reaches the target second pin of the analog input module, the target second pin detects the change in the analog test signal and converts it into a received analog signal. After the target second pin of the analog input module successfully receives the analog signal, the received analog signal is formally formed and further read and processed by the PLC master station.

[0060] S204. The PLC / DCS master station reads the recovery simulation signal and performs fault detection based on the simulation test signal and the recovery simulation signal.

[0061] In specific implementation, the PLC / DCS master station reads the recovered analog signal and performs fault detection based on the analog test signal and the recovered analog signal, including: calculating the characteristic deviation between the recovered analog signal and the analog test signal, and determining the corresponding fault type based on the relationship between the characteristic deviation and the corresponding threshold; there are multiple characteristic deviations, and different characteristic deviations correspond to different thresholds; the loss of the recovered analog signal is detected within the transmission cycle, and the corresponding fault type is determined based on the loss.

[0062] Specifically, the PLC master station reads the recovered analog signal from the target second pin of the analog input module and stores its characteristic parameters. It compares the analog test signal with the recovered analog signal, extracts multiple characteristic parameters (such as amplitude, phase, frequency, time delay, etc.), and calculates the deviation between them. The calculated deviation values ​​are compared with preset thresholds to determine if they exceed the normal range. Based on the relationship between different characteristic deviation values ​​and preset thresholds, a preset fault type library is matched to determine the specific fault type. Within each transmission cycle, it monitors whether the recovered analog signal is received. If it is not detected within a specified time, the loss is recorded, and the fault category is further analyzed, such as connection interruption, signal attenuation, or short circuit.

[0063] Optionally, after the PLC / DCS master station reads the recycled analog signal and performs fault detection based on the analog test signal and the recycled analog signal, the method further includes: after the PLC / DCS master station detects a fault, recording a fault log based on the fault information and triggering an alarm signal; when the fault reaches the target fault level, the PLC master station performs an emergency operation to prevent an accident from occurring.

[0064] In practice, when the PLC master station detects a fault, it extracts information such as the fault type, occurrence time, and scope of impact, and stores it in the fault log for subsequent analysis and maintenance. Based on the fault level, the PLC master station sends alarm signals to the upper-level system or operators, including audible and visual alarms, HMI interface prompts, or remote notifications, to remind relevant personnel to handle the situation promptly. The severity of the fault is compared with a preset target fault level threshold to determine whether emergency operations are necessary. When the fault reaches or exceeds the target fault level, the PLC master station executes preset emergency operations, such as cutting off power, shutting down the machine, activating backup equipment, or adjusting control strategies, to prevent equipment damage or safety accidents.

[0065] The method in this embodiment can be used to execute Figure 1The steps of the device embodiment shown are similar in principle and process, and will not be repeated here.

[0066] The specific implementation process of the functions and roles of each unit in the above device can be found in the implementation process of the corresponding steps in the above method, and will not be repeated here.

[0067] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this application according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0068] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A PLC / DCS remote I / O network fault detection device, characterized in that, The PLC / DCS remote IO network fault detection device includes a PLC / DCS master station and a remote IO station, wherein the PLC / DCS master station is connected to the remote IO station; the remote IO station includes an analog output module and an analog input module, wherein the analog output module includes multiple first pins, and among the multiple first pins there is an unoccupied target first pin; The analog input module includes multiple second pins, among which there are unoccupied target second pins. The target first pin is determined based on signal type, voltage level, and distance from the second pins. Specifically, the PLC master station obtains a list of currently unoccupied pins, performs signal type matching on the obtained free pins, matching output pins and input pins with the same signal type. The PLC master station then performs voltage level matching on the signal type-matched pin groups, matching output pins and input pins with compatible voltage or current ranges, obtaining a preliminary candidate pin group. The PLC master station analyzes the distance between each pair of output and input pins in the candidate pin group, retaining the pin pair with the optimal distance, obtaining an optimized target pin group. The optimal pair of pins is selected from the target pin group as the target first pin and target second pin. Each target first pin is connected to a corresponding target second pin to form an analog signal loop. The PLC / DCS master station is used to generate analog test signals and output the analog test signals to the target first pin in the analog output module; After the simulated test signal reaches the first pin of the target, it is transmitted through the simulated signal loop to the second pin of the target in the simulated input module, which corresponds to the first pin of the target, to form a recovered simulated signal; The PLC / DCS master station is also used to read the recovered analog signal and perform joint fault detection based on the time delay and pulse shape deviation of the analog test signal and the recovered analog signal; if a fault is detected, it automatically switches the untested idle pin to perform redundant detection on the regenerated analog test signal.

2. The apparatus according to claim 1, characterized in that, The PLC / DCS master station is also used to read the recovery simulation signal and perform fault detection based on the simulation test signal and the recovery simulation signal, including: The time delay between the simulated test signal and the recovered simulated signal is obtained as the time difference value; Based on the comparison between the time difference and the preset time threshold, it is determined whether there is a time delay anomaly and the corresponding time delay fault is identified. Waveform analysis is performed on the recovered analog signal to extract the pulse shape features corresponding to the analog test signal and calculate the pulse shape deviation value; Based on the comparison between the pulse shape deviation value and the preset shape deviation threshold, it is determined whether there is signal distortion abnormality and the corresponding waveform fault is identified. The fault category is determined by combining the analysis results of the time difference and pulse shape deviation.

3. The apparatus according to claim 1, characterized in that, The remote I / O station includes a digital output module and a digital input module. The digital output module includes multiple third pins, among which there are unoccupied target third pins. The digital input module includes multiple fourth pins, among which there are unused target fourth pins; each target third pin is connected to a corresponding target fourth pin to form a wiring loop; The PLC / DCS master station is used to continuously generate a transmission pulse signal based on the transmission cycle, and output the transmission pulse signal to any of the target third pins in the digital output module; After the transmitted pulse signal reaches the target third pin, it is transmitted through the wiring circuit corresponding to the target third pin to the target fourth pin in the digital input module, forming a received pulse signal.

4. The apparatus according to claim 1, characterized in that, After fault detection based on the simulated test signal and the recovered simulated signal, if a fault exists, the PLC / DCS master station is also used to determine the untested idle pin pairs among the target first pin and target second pin that have formed an simulated signal loop, select any idle pin pair as the pin pair used for fault detection, and generate the simulated test signal again.

5. The apparatus according to claim 3, characterized in that, After the recovery pulse signal is generated When the PLC / DCS master station does not read the recovery pulse signal, the first fault type is determined; When the PLC / DCS master station reads the recovery pulse signal, it determines the reading time and compares the reading time with the timeout time to perform the first fault detection. The PLC / DCS master station determines the reading period of the recovered pulse signal, calculates the difference between the reading period and the sending period, and performs a second fault detection based on the difference.

6. A method for fault detection in a PLC / DCS remote I / O network, characterized in that, The method is applied to the PLC / DCS remote IO network fault detection device according to any one of claims 1-5, and the method includes: Identify the target first pin in the first pin, and identify the target second pin in the second pin; the target first pin and the target second pin constitute an analog signal loop; The PLC / DCS master station generates a simulated test signal and transmits the simulated test signal to the first pin of the target. The simulated test signal passes through the first pin of the target and the simulated signal loop, and then reaches the second pin of the target to form a recovered simulated signal. The PLC / DCS master station reads the recovered analog signal and performs joint fault detection based on the time delay and pulse shape deviation of the analog test signal and the recovered analog signal.

7. The method according to claim 6, characterized in that, Determining the target first pin in the first pin and the target second pin in the second pin includes: Obtain the output and input pins that are idle in the remote I / O station; Based on the signal type and voltage level of the output pin and the input pin, pin pairs that meet the connection conditions are selected to form a candidate pin group; the candidate pin group includes a pair of matched output pins and input pins; Based on the distance between the output pin and the input pin in the candidate pin group, the candidate pin group is filtered to obtain the target pin group, and the target first pin and the target second pin are determined based on the target pin group.

8. The method according to claim 6, characterized in that, The PLC / DCS master station generates analog test signals, including: Identify the application scenarios of the PLC / DCS master station; Determine the application industry requirements based on the aforementioned application scenarios; The sending cycle range is determined based on the application scenario and the requirements of the application industry; Within the specified transmission cycle range, the transmission cycle value is determined based on historical fault data; Based on the transmission period value, a transmission period parameter is set, and a simulated test signal is continuously generated under the transmission period parameter. The PLC / DCS master station monitors the network status of the remote IO station in real time and adjusts the transmission cycle value based on the network status.

9. The method according to claim 6, characterized in that, The PLC / DCS master station reads the recovered analog signal and performs joint fault detection based on the time delay and pulse shape deviation of the analog test signal and the recovered analog signal, including: Calculate the characteristic deviation between the recovered simulated signal and the simulated test signal, and determine the corresponding fault type based on the relationship between the characteristic deviation and the corresponding threshold; there are multiple characteristic deviations, and different characteristic deviations correspond to different thresholds; During the transmission cycle, the loss of the recovered analog signal is detected, and the corresponding fault type is determined based on the loss.

10. The method according to claim 6, characterized in that, The PLC / DCS master station reads the recovered analog signal, and after performing joint fault detection based on the time delay and pulse shape deviation of the analog test signal and the recovered analog signal, the method further includes: After the PLC / DCS master station detects a fault, it records a fault log based on the fault information and triggers an alarm signal. When the fault reaches the target fault level, the PLC / DCS master station performs emergency operations.

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