Fault diagnosis method and device in PLC system, PLC system and storage medium

Abstract

The invention relates to a fault diagnosis method and device in a PLC system, the PLC system and a storage medium, and belongs to the technical field of industrial automation control. The method comprises the following steps: acquiring a starting signal and a plurality of shutdown fault signals of equipment in real time; when it is detected that the starting signal jumps from starting to stopping, a reverse analysis process is triggered, and multiple shutdown fault signals are polled according to a preset priority sequence; if a certain shutdown fault signal is in a fault triggering state, generating a corresponding fault code, and keeping the duration of the fault code to be not less than a preset duration through a timer; and transmitting the fault code to the HMI for display, and recording the fault code to a PLC internal fault log database. According to the invention, through embedded real-time diagnosis and a reverse trigger mechanism, the real-time performance of fault capture and the automation of diagnosis are realized, and the efficiency of fault diagnosis is improved. And meanwhile, the diagnosis function block is only activated when the equipment is shut down, so that the CPU occupancy rate is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial automation control, and particularly to a fault diagnosis method, device, PLC system and storage medium within a PLC system. Background Art

[0002] In the field of industrial automation, a PLC (Programmable Logic Controller) system is widely used in the control of production line equipment. When the equipment breaks down and stops, the traditional method relies on an HMI (Human Machine Interface), such as a SCADA system, to collect PLC signals for fault diagnosis. However, the traditional technology has the following significant defects: the signal acquisition delay is too high, and the fault diagnosis efficiency is low. External data acquisition is limited by the communication rate (such as the PROFINET / OPC UA protocol), and the minimum acquisition period of the HMI is 500 ms. Even when using a dedicated PDA software, the period is still ≥20 ms. For transient faults that last only for a few milliseconds (such as power supply flickering or signal jumps caused by poor contact), the traditional solution cannot capture the fault signals, resulting in the inability to reproduce the fault and the unclear cause. Summary of the Invention

[0003] Based on this, it is necessary to provide a fault diagnosis method, device, PLC system and storage medium within a PLC system with relatively high fault diagnosis efficiency for the above technical problems.

[0004] A fault diagnosis method within a PLC system provided by the present invention embeds a diagnostic function block in the PLC program and synchronously scans and executes it with the device start / stop logic program. The method includes:

[0005] Real-time collect the start signal of the device and multiple stop fault signals;

[0006] When it is detected that the start signal jumps from start to stop, trigger a reverse parsing process, and poll the multiple stop fault signals in a preset priority order;

[0007] If a certain stop fault signal is in a fault trigger state, generate a corresponding fault code, and keep the duration of the fault code by a timer for not less than a preset duration;

[0008] Transmit the fault code to the HMI for display and record it in the PLC internal fault log database.

[0009] In one embodiment, the stop fault signal includes at least one of an abnormal digital input signal, an analog input signal exceeding a threshold, a communication interruption signal, and a device safety interlock signal.

[0010] In one embodiment, the triggering of the reverse parsing process and polling the multiple stop fault signals in a preset priority order includes:

[0011] Within the same scan cycle when the start signal jumps, the shutdown fault signals are polled in the order of priority, and the fault source is locked through the internal status register of the PLC.

[0012] In one embodiment, it further includes:

[0013] Dynamically adjust the preset priority according to historical fault frequency statistics, equipment operation stage, and fault severity level.

[0014] In one embodiment, the synchronous scanning execution with the equipment start / stop logic program includes:

[0015] Place the diagnostic function block and the equipment start / stop logic program in the same PLC organization block to ensure that both are executed within the same scan cycle.

[0016] In one embodiment, the timer is a PLC pulse timer, and the hold time can be configured from 2 to 5 seconds, and during this period, the HMI is allowed to read the fault code multiple times.

[0017] The present invention also provides a fault diagnosis device within a PLC system, which embeds a diagnostic function block in the PLC program and executes it synchronously with the equipment start / stop logic program. The device includes:

[0018] A signal acquisition module for real-time acquisition of the equipment start signal and multiple shutdown fault signals;

[0019] A reverse parsing module for triggering a reverse parsing process when it detects that the start signal jumps from start to stop, and polling the multiple shutdown fault signals in the order of preset priority;

[0020] A code generation module for generating a corresponding fault code if a certain shutdown fault signal is in a fault trigger state, and maintaining the duration of the fault code by a timer for not less than a preset duration;

[0021] A communication interface module for transmitting the fault code to the HMI for display and recording it in the PLC internal fault log database.

[0022] In one embodiment, the reverse parsing module is further used to support at least one optimization strategy among conflict detection based on the fault signal trigger time, fault filtering combined with the equipment operation state, and automatic association of fault codes with the maintenance knowledge base.

[0023] The present invention also provides a PLC system, including:

[0024] At least one CPU module for executing the fault diagnosis method within the PLC system described in any one of the above;

[0025] A distributed I / O module for collecting equipment start / stop and fault signals;

[0026] The HMI terminal displays the fault code and the handling suggestions.

[0027] In one embodiment, the CPU module adopts a resource allocation strategy to allocate an independent memory area for the diagnostic function block, limit the maximum execution time of the diagnostic function block to not more than a preset percentage of the scan cycle, and preload the fault code mapping table when the PLC starts.

[0028] The above-mentioned fault diagnosis method, device, PLC system and storage medium in the PLC system realize the real-time fault capture and automatic diagnosis through the embedded real-time diagnosis and reverse trigger mechanism, improving the efficiency of fault diagnosis. At the same time, the diagnostic function block is only activated when the device is shut down, greatly reducing the CPU occupancy rate. Brief Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0030] Figure 1 It is a flowchart of the fault diagnosis method in the PLC system according to an embodiment of the present invention;

[0031] Figure 2 It is a schematic diagram of the fault diagnosis device in the PLC system according to an embodiment of the present invention;

[0032] Figure 3 It is a schematic diagram of the PLC system according to an embodiment of the present invention;

[0033] Figure 4 It is the internal structure diagram of a computer device according to an embodiment of the present invention. Detailed Embodiments

[0034] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0035] In the field of industrial automation, PLC (Programmable Logic Controller) systems are widely used in the control of production line equipment. When a device fails and stops, the traditional method relies on an HMI (Human Machine Interface), such as a SCADA (Supervisory Control And Data Acquisition) system, to collect PLC signals for fault diagnosis (such as the Siemens WINCC system). However, the existing technology has the following significant defects:

[0036] The signal acquisition delay is too high, and the fault diagnosis efficiency is low. External data acquisition is limited by the communication rate (such as the PROFINET / OPC UA protocol). The minimum acquisition cycle of the HMI is 500 ms. Even when using a dedicated PDA software, the cycle is still ≥20 ms. For transient faults that last only a few milliseconds (such as power glitches and signal jumps caused by poor contact), the traditional solution cannot capture the fault signals, resulting in "ghost accidents" (faults that cannot be reproduced and the causes are unknown).

[0037] Fault diagnosis relies on manual analysis. After a fault occurs, engineers need to manually retrieve historical data and check the stop conditions one by one (such as fault signal priority and logical relevance), which takes several minutes to several hours and seriously affects production efficiency.

[0038] The CPU resource occupancy rate is high. The traditional solution uses a continuous polling method (such as the periodic interrupt OB35). When the number of devices is large (such as 50+ devices), the CPU load rate exceeds 30%, which easily causes system response delays.

[0039] The existing technology generally improves the diagnosis efficiency by optimizing the data acquisition frequency, but it does not solve the core problems of internal real-time diagnosis of PLCs and millisecond-level fault trigger analysis. Therefore, there is an urgent need for a fault diagnosis solution that is embedded inside the PLC system and executed synchronously with the device start / stop logic to eliminate external acquisition delays and achieve 100% transient fault capture.

[0040] The following combines Figures 1 - 4 to describe the fault diagnosis method, device, PLC system, and storage medium within the PLC system of the present invention.

[0041] As Figure 1 shown, in one embodiment, a fault diagnosis method within a PLC system includes the following steps:

[0042] Step S110, real-time collect the start signal of the device and multiple stop fault signals.

[0043] Embed a diagnostic function block in the PLC program, which is scanned and executed synchronously with the device start / stop logic program. Place the diagnostic function block and the device start / stop logic program in the same PLC organization block to ensure that both are executed within the same scan cycle, and both program blocks can be scanned simultaneously, with the scan cycle ≤ 10 ms. Optionally, embed the diagnostic function block (such as FB_Diagnosis) in the PLC main loop program (such as OB1) to run synchronously with the device control logic (the default scan cycle is set to 5 ms). Real-time collect the device start signal and N stop fault signals, where N is a natural number greater than 1. The start signal is a boolean value, 1 represents start, and 0 represents stop. The stop fault signal is a boolean or analog value, and 1 or exceeding the threshold represents fault trigger. Embed the diagnostic function block in the PLC program block to execute synchronously with the device start / stop logic (scan cycle ≤ 10 ms), completely avoiding the external acquisition delay of HMI / SCADA. It can improve the capture success rate of 5 ms-level transient faults (such as power flash and poor contact) from 0% in the traditional solution to 100%. Among them, the stop fault signal includes at least one of abnormal digital input signal, analog input signal exceeding the threshold, communication interruption signal, and device safety interlock signal, supporting multiple signal types, compatible with mixed signal diagnosis of digital quantity (DI), analog quantity (AI), communication status, etc., covering more than 90% of industrial fault types (such as voltage fluctuation, sensor failure, network flash).

[0044] Step S120, when it is detected that the start signal jumps from start to stop, trigger the reverse parsing process, and poll the multiple stop fault signals in the preset priority order.

[0045] When it is detected that the start signal (#Logic.Start[1]) jumps from 1 to 0, trigger the reverse parsing process, poll the N stop fault signals (#Logic."Now STOP1"[n]) in the preset priority order, and generate a fault code. Within the same scan cycle when the start signal jumps, poll the stop fault signals in the priority order, lock the fault source through the PLC internal status register, with the fault location time ≤ 1 ms, achieving millisecond-level fault capture and avoiding the lag of manual troubleshooting. Optionally, the preset priority is dynamically adjusted, and the adjustment basis includes historical fault frequency statistics, device operation stage (start / run / stop), and fault severity level (emergency stop / warning). Support the adjustment of the fault signal weight based on historical data (such as polling high-frequency faults first). In a complex production line (such as 50+ devices), the fault identification accuracy can be increased to 99.8% (about 85% for the traditional static priority scheme).

[0046] Step S130, if a certain stop fault signal is in the fault trigger state, generate the corresponding fault code, and keep the duration of the fault code by the timer not less than the preset duration.

[0047] If the i-th shutdown fault signal is in a fault trigger state, a corresponding fault code i is generated, where i is a natural number less than or equal to N, and this code is maintained for ≥ 2 seconds through a timer. The timer is a PLC pulse timer (TP), and the holding time can be configured from 2 to 5 seconds, and the HMI is allowed to read the fault code multiple times during this period.

[0048] Step S140: Transmit the fault code to the HMI for display and record it in the PLC internal fault log database.

[0049] The fault code is held for ≥ 2 seconds through the PLC pulse timer to ensure complete reading by the HMI, and is associated with a predefined fault description (such as "Code 101: Motor overload"). Compared with traditional manual analysis (which takes 5 - 30 minutes), the present invention enables the display of the fault cause within seconds, and the equipment restart time is shortened by 70%. The fault code is transmitted to the HMI through the PLC-HMI data interface (such as DB200), and the HMI calls the predefined fault library to display the description and handling suggestions (such as "Code 101: Check the motor load current"). The fault log is stored in the PLC internal memory card in CSV format, recording the timestamp, fault code, and equipment number.

[0050] The fault diagnosis method within the PLC system of this embodiment realizes the real-time nature of fault capture and the automation of diagnosis through the embedded real-time diagnosis and reverse trigger mechanism. At the same time, the diagnostic function block is only executed when the equipment shutdown event is triggered, greatly reducing the CPU occupancy rate. Based on the measured data of Siemens S7-1500, it is reduced from 5 - 30% of the traditional continuous polling scheme to less than 1%. The fault code synchronization across PLC units is achieved through PROFINET / PROFIBUS. In a large-scale production line (such as a chemical production line), the global fault location error ≤ 10 ms. Breakthrough progress has been made in dimensions such as fault capture real-time nature, diagnosis automation, and resource utilization rate, and it can be applied to high-precision and high-reliability industrial scenarios such as automobile manufacturing and semiconductor production lines, with significant economic benefits and industry universality. The following table shows the experimental data comparison:

[0051] Index Traditional solution (HMI / SCADA) Solution of the present invention Minimum fault capture duration 20 ms 1 ms (PLC cycle) Fault capture success rate at 5 ms 0％ 100％ Fault location time 5 - 30 minutes ≤1 second CPU occupancy rate of 50 devices 30％ <1％ False alarm rate of fault codes 15％ 0.2％

[0052] The PLC system internal fault diagnosis device provided by the present invention will be described below. The PLC system internal fault diagnosis device described below can be mutually referred to the PLC system internal fault diagnosis method described above.

[0053] As Figure 2As shown, in one embodiment, a fault diagnosis device within a PLC system embeds a diagnostic function block in the PLC program and synchronously scans and executes it with the device start / stop logic program. The device includes a signal acquisition module 210, a reverse parsing module 220, a code generation module 230, and a communication interface module 240.

[0054] The signal acquisition module 210 is used to collect device start signals and multiple shutdown fault signals in real time.

[0055] The reverse parsing module 220 is used to trigger a reverse parsing process when it detects that the start signal changes from start to stop, and polls the multiple shutdown fault signals in a preset priority order.

[0056] The code generation module 230 is used to generate a corresponding fault code if a certain shutdown fault signal is in a fault-triggered state, and maintain the duration of the fault code through a timer for no less than a preset duration.

[0057] The communication interface module 240 transmits the fault code to the HMI for display and records it in the PLC internal fault log database.

[0058] In this embodiment, the reverse parsing module 220 is further used to support at least one optimization strategy among conflict detection based on the fault signal trigger time, fault filtering combined with the device operating state, and automatic association of fault codes with the maintenance knowledge base.

[0059] As Figure 3 shown, in one embodiment, a PLC system includes at least one CPU module 310, a distributed I / O module 320, and an HMI terminal 330.

[0060] At least one CPU module is used to execute the PLC system internal fault diagnosis method described above;

[0061] The distributed I / O module is used to collect device start / stop and fault signals;

[0062] The HMI terminal is used to display fault codes and processing suggestions.

[0063] In this embodiment, the CPU module adopts a resource allocation strategy to allocate an independent memory area for the diagnostic function block, limit the maximum execution time of the diagnostic function block to no more than a preset percentage of the scan cycle, and preload the fault code mapping table when the PLC starts. The fault code mapping table is stored in an independent data block (DB), and the maximum execution time of the diagnostic program is limited to ≤1% of the scan cycle to ensure stability in multi-device and high-real-time scenarios.

[0064] Figure 4 Illustrates a schematic diagram of the physical structure of an electronic device. The electronic device can be a smart terminal, and its internal structure diagram can be asFigure 4 As shown in the figure. The electronic device includes a processor, a memory, and a network interface connected via a system bus. Among them, the processor of the electronic device is used to provide computing and control capabilities. The memory of the electronic device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the electronic device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, it realizes a fault diagnosis method within the PLC system. This method includes:

[0065] Real-time collect the startup signal and multiple shutdown fault signals of the device;

[0066] When it is detected that the startup signal changes from startup to stop, trigger a reverse parsing process, and poll the multiple shutdown fault signals in the preset priority order;

[0067] If a certain shutdown fault signal is in a fault trigger state, generate a corresponding fault code, and keep the duration of the fault code by a timer not less than a preset duration;

[0068] Transmit the fault code to the HMI for display and record it in the PLC internal fault log database.

[0069] Those skilled in the art can understand that Figure 4 The structure shown in the figure is only a block diagram of some structures related to the solution of the present invention, and does not constitute a limitation on the electronic device to which the solution of the present invention is applied. The specific electronic device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements.

[0070] On the other hand, the present invention also provides a computer storage medium storing a computer program. When the computer program is executed by a processor, it realizes a fault diagnosis method within the PLC system. This method includes:

[0071] Real-time collect the startup signal and multiple shutdown fault signals of the device;

[0072] When it is detected that the startup signal changes from startup to stop, trigger a reverse parsing process, and poll the multiple shutdown fault signals in the preset priority order;

[0073] If a certain shutdown fault signal is in a fault trigger state, generate a corresponding fault code, and keep the duration of the fault code by a timer not less than a preset duration;

[0074] Transmit the fault code to the HMI for display and record it in the PLC internal fault log database.

[0075] In another aspect, a computer program product or a computer program is provided. The computer program product or the computer program includes computer instructions, and the computer instructions are stored in a computer-readable storage medium. A processor of an electronic device reads the computer instructions from the computer-readable storage medium, and when the processor executes the computer instructions, a fault diagnosis method within a PLC system is implemented. The method includes:

[0076] Real-time collect the start signal and multiple shutdown fault signals of the device;

[0077] When it is detected that the start signal jumps from start to stop, trigger a reverse parsing process, and poll the multiple shutdown fault signals in the preset priority order;

[0078] If a certain shutdown fault signal is in a fault trigger state, generate a corresponding fault code, and keep the duration of the fault code by a timer for not less than a preset duration;

[0079] Transmit the fault code to the HMI for display and record it in the PLC internal fault log database. Those of ordinary skill in the art can understand that all or part of the processes of implementing the methods in the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database or other medium used in the various embodiments provided by the present invention can include non-volatile and / or volatile memories. Non-volatile memories can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memories can include random access memory (RAM) or external cache memory.

[0080] By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0081] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0082] The embodiments described above merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the appended claims.

Claims

1. A fault diagnosis method within a PLC system, characterized in that, Embed a diagnostic function block in the PLC program and execute it synchronously with the device start / stop logic program. The method includes: Real-time collect the start signal of the device and multiple shutdown fault signals; When it is detected that the start signal changes from start to stop, trigger a reverse parsing process and poll the multiple shutdown fault signals in the preset priority order; If a certain shutdown fault signal is in a fault-triggered state, generate a corresponding fault code and keep the duration of the fault code by a timer for no less than a preset duration; Transmit the fault code to the HMI for display and record it in the PLC internal fault log database.

2. The method for fault diagnosis in the PLC system according to claim 1, wherein The shutdown fault signal includes at least one of abnormal digital input signal, analog input signal exceeding the threshold, communication interruption signal, and device safety interlock signal.

3. The PLC system internal fault diagnosis method according to claim 1, characterized in that, The triggering of the reverse parsing process and polling the multiple shutdown fault signals in the preset priority order includes: In the same scan cycle when the start signal changes, poll the shutdown fault signals in the priority order and lock the fault source through the PLC internal status register.

4. The PLC system internal fault diagnosis method according to claim 1, wherein It also includes: Dynamically adjust the preset priority according to historical fault frequency statistics, device operation stage, and fault severity level.

5. The method for fault diagnosis within a PLC system according to claim 1, wherein The synchronous scan execution with the device start / stop logic program includes: Place the diagnostic function block and the device start / stop logic program in the same PLC organization block to ensure that both are executed in the same scan cycle.

6. The PLC system internal fault diagnosis method according to claim 1, wherein, The timer is a PLC pulse timer, and the holding time can be configured from 2 to 5 seconds, and the HMI is allowed to read the fault code multiple times during this period.

7. A fault diagnosis device within a PLC system, characterized in that, Embed a diagnostic function block in the PLC program and execute it synchronously with the device start / stop logic program. The device includes: A signal acquisition module for real-time collecting the device start signal and multiple shutdown fault signals; A reverse parsing module for triggering a reverse parsing process and polling the multiple shutdown fault signals in the preset priority order when it is detected that the start signal changes from start to stop; A code generation module for generating a corresponding fault code if a certain shutdown fault signal is in a fault-triggered state and keeping the duration of the fault code by a timer for no less than a preset duration; A communication interface module for transmitting the fault code to the HMI for display and recording it in the PLC internal fault log database.

8. The PLC system internal fault diagnosis device according to claim 7, characterized in that, The reverse parsing module is also used to support at least one optimization strategy such as conflict detection based on the fault signal trigger time, fault filtering combined with the device operation state, and automatic association of fault codes with the maintenance knowledge base.

9. A PLC system, characterized in that, It includes: At least one CPU module for executing the PLC system internal fault diagnosis method according to any one of claims 1-6; A distributed I / O module for collecting device start / stop and fault signals; An HMI terminal for displaying fault codes and treatment suggestions.

10. The PLC system according to claim 9, wherein, The CPU module adopts a resource allocation strategy to allocate an independent memory area for the diagnostic function block, limit the maximum execution time of the diagnostic function block to not more than a preset percentage of the scan cycle, and preload the fault code mapping table when the PLC starts.

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