PLC (Programmable Logic Controller) one-main multi-standby redundancy control system and control method thereof
By introducing a real-time container environment and a redundancy management module into the PLC system, a master-slave redundant control is achieved, which solves the problems of high hardware cost and resource waste in the existing technology, improves the system reliability and flexibility, and is suitable for a variety of industrial application scenarios.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-06
- Publication Date
- 2026-03-13
AI Technical Summary
Existing PLC-based redundancy control systems suffer from high hardware costs, significant resource waste, inability to expand to multiple backup systems, limited switching strategies, and low resource utilization, making it difficult to meet the flexible, low-cost, and highly reliable control requirements of intelligent manufacturing.
Multiple PLC devices are used, with a real-time container environment deployed on each device. The main controller and the backup controller keep data synchronized, and the backup controller is in a suspended execution state. The redundancy management module monitors in real time and selects the optimal backup controller to switch to the main controller according to a preset weight strategy, so as to realize one main and multiple backup redundant control.
It reduces resource consumption, improves system reliability and flexibility, supports multi-level fault tolerance, reduces hardware costs, is suitable for application scenarios with different security levels, and meets the needs of industrial real-time control.
Smart Images
Figure CN121657564A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of industrial automation control systems, specifically to a PLC one-master-multiple-standby redundant control system and its control method. Background Technology
[0002] In industrial control systems, the PLC (Programmable Logic Controller) is a critical control unit, and its continuous and reliable operation directly affects production safety and efficiency. To avoid system downtime caused by single points of failure, existing technologies generally adopt hardware redundancy solutions, with a typical structure being a dual-machine hot standby system with one master and one backup.
[0003] In existing technologies, redundancy schemes for "one primary and one backup" dual-machine hot standby systems are mainly implemented through the following methods: Hardware redundancy: Two identical PLC devices need to be configured, one as the main controller and the other as a backup controller; Data synchronization: The main controller and the backup controller copy key information such as I / O status, memory variables, and program execution location in real time through a dedicated synchronization link; Hot standby operation: The standby controller needs to continuously run the same control program to keep synchronized with the main controller so that it can switch over in milliseconds when a failure occurs.
[0004] However, the above-mentioned solutions have the following defects and shortcomings in implementation: 1) High hardware costs: One or more PLC devices of the same specifications must be configured as backups, which doubles the equipment investment; 2) Serious waste of resources: The backup controller needs to run the control program all the time even when it is not in operation, continuously occupying CPU, memory and power resources; 3) Only supports one primary and one backup: Traditional architectures are difficult to scale to "one primary and multiple backups", lack flexibility, and cannot cope with multiple consecutive failure scenarios; 4) Single switching strategy: The switching between primary and backup controllers relies on fixed roles and lacks a dynamic priority scheduling mechanism, making it impossible to intelligently select the best backup controller based on the health status or load of the equipment.
[0005] 5) In addition, since the main and backup machines are independent physical devices, the overall resource utilization rate of the system is low, making it difficult to meet the requirements of intelligent manufacturing for flexible, low-cost, and highly reliable control.
[0006] Therefore, there is an urgent need to provide a new solution to address the defects and shortcomings of the existing technologies. Summary of the Invention
[0007] To address the deficiencies and shortcomings of the existing technologies, this invention provides a PLC one-master-multiple-standby redundant control system and its control method.
[0008] The specific solution provided by this invention is as follows: A PLC-based master-slave redundant control system, characterized in that: the system includes: Multiple PLC devices, each of which has real-time processing capability, and each of which is equipped with a preset real-time container environment; The system comprises one main controller and multiple backup controllers, both operating in a pre-defined environment, and deployed on the same or different PLC devices. The main controller and the backup controller maintain synchronized operating status data; The main controller is in a normal control task execution state; The backup controller is in a control task suspended execution state, and immediately switches from the control task suspended execution state to the control task normal execution state after receiving a wake-up signal; The redundancy management module is connected to both the main controller and the backup controller to monitor their real-time status. When the main controller fails or a switching command is received, the module selects the optimal switching target from multiple backup controllers based on a preset weighting strategy. It then sends a wake-up signal to the backup controller to switch it from a suspended control task execution state to a normal control task execution state. Finally, the backup controller replaces the current main controller to continue executing the control task.
[0009] As a further preferred embodiment of the present invention, each of the PLC devices is equipped with an ECS real-time container environment.
[0010] As a further preferred embodiment of the present invention, the operating environment that meets the preset requirements includes an operating environment that meets the preset standards.
[0011] As a further preferred embodiment of the present invention, when the backup controller is in a control task suspension execution state: 1) The backup controller does not participate in CPU time slice allocation and its CPU utilization rate is 0%; 2) The backup controller stores the complete memory context and I / O mapping.
[0012] As a further preferred embodiment of the present invention, when the backup controller immediately switches from the control task suspension execution state to the control task normal execution state after receiving the wake-up signal, it continues to execute the control task from the most recently updated pause point.
[0013] As a further preferred embodiment of the present invention, each of the backup controllers is provided with a pause point, and the pause point maintains a signal connection with the main controller through a signal waiting interface.
[0014] As a further preferred embodiment of the present invention, the synchronization of operating status data between the main controller and the backup controller includes: The main controller synchronizes its key operating status data to each backup controller via a communication link through a synchronization program in an event-triggered manner. Each backup controller updates its key operating status data when the control task is suspended and synchronizes the updated key operating status data to the pause point through the corresponding signal waiting interface. The new main controller then obtains the last synchronized data from the pause point and begins the current cycle. The key operational status data includes at least variable area snapshots, program counters, and timer status data.
[0015] As a further preferred embodiment of the present invention, each of the backup controllers is configured with a corresponding switching priority value, which is calculated according to the following formula: Y = aX1 + bX2 + cX3 + dX4 + eX5; In the formula, Y represents the corresponding switching priority value configured for each standby controller; X1 is the device performance score for the backup controller; X2 is the current network latency rate of the backup controller; X3 represents the current load rate of the standby controller; X4 represents the historical stability score of the backup controller; X5 is a score for the user selection strategy of the backup controller; a, b, c, d, and e are the weighting coefficients corresponding to the backup controller's device performance score, current network latency, current load rate, historical stability score, and user selection strategy score, respectively.
[0016] As a further preferred embodiment of the present invention, the preset weighting strategy is set as follows: when the current main controller is detected to have failed or a switching instruction is received, the optimal switching target is selected from multiple backup controllers according to the switching priority value from high to low, and a wake-up signal is sent to it.
[0017] Furthermore, the present invention also provides a control method for a PLC master-slave redundant control system, characterized by comprising the following steps: S100: Deploys a pre-defined real-time container environment for multiple PLC devices; S200: Deploy one main controller and multiple backup controllers on the same or different PLC devices and run them in an operating environment that meets preset requirements; S300: Keeps the main controller and the standby controller periodically synchronized in terms of operating status data; S400: The main controller is in the normal execution state of the control task, and the backup controller is in the suspended execution state of the control task. S500: The redundancy management module performs real-time status monitoring of the main controller and the backup controller. When the current main controller fails or a switching command is received, the optimal switching target is selected from multiple backup controllers according to the preset weight strategy and used as the new main controller. A wake-up signal is sent to the backup controller to switch the control task from the suspended execution state to the normal execution state, and the backup controller replaces the current main controller to continue to execute the control task.
[0018] Compared with existing technologies, the technical effects that this invention can achieve include: 1) This invention provides a PLC one-master-multiple-standby redundant control system and its control method. By setting the standby controller to a control task suspension execution state, and immediately switching from the control task suspension execution state to the control task normal execution state after receiving a wake-up signal, the operating system signal waiting mechanism is applied to the one-master-multiple-standby redundant control system. This makes the CPU usage state approach 0 when the standby controller is in the control task suspension execution state, which greatly reduces resource consumption. At the same time, it retains the millisecond-level wake-up capability, combining the energy saving of cold standby and the response speed of hot standby. This significantly reduces system resource consumption and is significantly more energy-efficient than traditional hot standby solutions, thus extending equipment life.
[0019] 2) This invention provides a PLC one-master-multiple-standby redundant control system and its control method. By adopting a "one-master-multiple-standby" PLC redundancy architecture, it breaks through the limitations of the traditional "one-master-one-standby" architecture, improves the system reliability and fault tolerance, and can sequentially activate multiple standby controllers according to the switching priority value after the main controller fails. It supports multi-level fault tolerance and is suitable for critical production lines or unattended scenarios, effectively improving the system's survivability in multi-fault scenarios.
[0020] 3) This invention provides a PLC one-master-multiple-standby redundant control system and its control method, which introduces a standby controller selection mechanism based on priority value calculation, supports dynamic determination of switching targets based on equipment status, performance indicators or user strategies, and improves the system's intelligence level and reliability.
[0021] 4) This invention provides a PLC one-master-multiple-standby redundant control system and its control method. It utilizes real-time container technology to realize flexible deployment and resource sharing of the master controller and standby controllers. Redundant systems can be built without additional hardware purchases, significantly reducing user costs. There is no need to purchase additional PLC equipment dedicated to standby controllers. Redundancy functions can be achieved using existing resources, saving 30% to 50% of hardware investment.
[0022] 5) This invention provides a PLC one-master-multiple-standby redundant control system and its control method. The master controller and standby controller can be deployed across multiple PLC devices or coexist within the same PLC device. It is suitable for application scenarios with different safety levels. For example, the cross-device deployment method can be used in application scenarios with high safety requirements, and the coexistence deployment method within the same device can be used in application scenarios with low-cost redundancy requirements, thereby meeting the deployment requirements of different application scenarios and effectively increasing the scope of application.
[0023] 6) This invention provides a PLC one-master-multiple-standby redundant control system and its control method. The wake-up process can be directly scheduled and executed by the operating system. The delay is controllable. The measured switching time can be controlled within 20ms, which meets the real-time control requirements of most industries, so as to realize the rapid switching process from standby controller to master controller.
[0024] 7) This invention provides a PLC one-master-multiple-standby redundant control system and its control method, which enhances the system's flexibility and configurability. By dynamically adjusting the priority value of the standby controller, increasing or decreasing the number of standby controllers, and remotely configuring redundancy strategies, it facilitates system maintenance and upgrades. At the same time, it promotes the development of PLCs towards lightweight, software-based, and intelligent directions, and provides basic support for new architectures such as edge computing, cloud PLC, and digital twins in the future. Attached Figure Description
[0025] Figure 1 The diagram shown is a logic structure diagram of the control system provided by the present invention.
[0026] Figure 2 The diagram shows the steps of the control method provided by the present invention. Detailed Implementation
[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0028] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0030] [First Embodiment] like Figure 1 As shown, the first embodiment of the present invention provides a PLC one-master-multiple-standby redundant control system, the system comprising: Multiple PLC devices are used, each with real-time processing capabilities, and each PLC device is equipped with a preset real-time container environment; in this embodiment, each PLC device is equipped with an ECS real-time container environment.
[0031] ECS (Edge Container Stack) is a lightweight real-time container designed for mission-critical cloud-native architectures. The container engine requires approximately 1MB of disk space and consumes about 6MB of memory, with a startup time of <50ms. Unlike Docker, ECS is a lightweight container built on the SylixOS hard real-time operating system. Real-time task response within the container can reach the microsecond level, and interrupt response can reach the nanosecond level.
[0032] ECS and the SylixOS kernel have a strongly bound, deeply integrated relationship, rather than an application software and operating system relationship. Through kernel-level modifications, a secure and isolated runtime environment is achieved, and the ECS runtime and container image package specifications are implemented in accordance with OCI standards.
[0033] PLC devices typically occupy relatively small and limited resources. Using ECS real-time containers can create an isolated operating environment for such resource-constrained devices, allowing multiple PLC devices to operate independently of each other, ensuring the safety and reliability of the equipment, and also providing software-defined capabilities.
[0034] There is one main controller and multiple backup controllers. Both the main controller and the backup controllers operate in an operating environment that meets preset requirements. In this embodiment, the operating environment that meets preset requirements includes an operating environment that meets preset standards.
[0035] The pre-defined standards should include at least IEC 61131-3 or IEC 61499. Among them, The IEC 61131-3 standard is a core international standard in the field of industrial automation regarding the programming language and software architecture for programmable logic controllers (PLCs). Different manufacturers can refer to this standard to implement different operating environments. However, in terms of development methods, it can achieve a unified language, standardized structure, modular design, and support for multi-language mixed programming. The integrated IEC 61131-3 standard used in this embodiment provides a runtime environment that conforms to IEC 61131-3 and can support the operation of PLC applications written according to the IEC 61131-3 specification.
[0036] The IEC 61499 standard is a revolutionary standard in the field of industrial automation, considered a modern evolution of IEC 61131-3, and specifically designed for distributed, modular, and reconfigurable industrial control systems. Compared to the IEC 61131-3 standard, the IEC 61499 standard has advantages such as distributed architecture, event-driven operation, and high portability. The IEC 61499 standard used in this embodiment provides a compliant runtime environment that supports the operation of PLC applications written according to the IEC 61499 specification.
[0037] By integrating the main controller and the backup controller into an operating environment that meets preset standard requirements, the smooth execution of PLC logic applications is ensured.
[0038] Furthermore, the main controller and backup controller can be deployed on the same or different PLC devices to suit application scenarios with different safety levels. For example, cross-device deployment (i.e., deployment on different PLC devices) can be used in applications with high safety requirements, while coexistence within the same device (i.e., deployment on the same PLC device) can be used in applications with low-cost redundancy requirements. This satisfies the deployment needs of different application scenarios and effectively expands the scope of application. The main controller and the backup controller maintain operational status data synchronization; in this embodiment, maintaining operational status data synchronization between the main controller and the backup controller includes: The main controller synchronizes its key operational status data to each backup controller via a communication link through a synchronization program in an event-triggered manner. In this embodiment, the key operational status data includes at least variable area snapshots, program counters, and timer status data. Each backup controller updates its key operational status data when the control task is suspended, and synchronizes this key operational status data update to the pause point through the corresponding signal waiting interface. This allows the new main controller to obtain the last synchronized data from the pause point and start the current cycle. In this embodiment, data synchronization between the main controller and the backup controller is performed through a synchronization program deployed on the PLC device and in operation, rather than by the PLC device itself on which the main controller and the backup controller are deployed. Figure 1 As shown, during operation, PLC device A will perform a real-time synchronization process with backup devices PLC devices B and C through a non-periodic event-triggered method via a synchronization program deployed on its device. That is, each time PLC device A performs a control operation, it will perform a synchronization process with PLC devices B and C.
[0039] When the main PLC device A fails, the standby device can start running immediately. The data it uses during operation is the data that was last synchronized by the main device. According to the running process defined by the IEC61131-3 and IEC61499 standards, once the PLC application is running, it works periodically and can continue working from the current cycle using the data from the last synchronization.
[0040] In this embodiment, The main controller is in a normal control task execution state; The standby controller is in the state of suspended execution of control tasks, and immediately switches from the state of suspended execution of control tasks to the state of normal execution of control tasks upon receiving a wake-up signal. It is worth noting that when the backup controller is in the state of suspended control task execution: 1) The standby controller does not participate in CPU time slice allocation and its CPU utilization rate is 0%; 2) The standby controller stores the complete memory context and I / O mapping; It significantly reduces resource consumption while retaining millisecond-level wake-up capability, combining the energy efficiency of cold standby with the response speed of hot standby. It greatly reduces system resource consumption and is significantly more energy-efficient than traditional hot standby solutions, effectively extending equipment lifespan.
[0041] In this embodiment, upon receiving a wake-up signal, the backup controller immediately switches from the control task suspension execution state to the control task normal execution state, and continues to execute the control task from the most recently updated pause point. This meets the real-time control requirements of most industries, enabling a rapid switchover process from the backup controller to the main controller. It also avoids the continuous occupation of CPU, memory, and power resources caused by the backup controller needing to run the control program 24 / 7 even when not in operation. In this implementation, each backup controller is equipped with a pause point, which maintains a signal connection with the main controller through a signal waiting interface (e.g., `sem_wait()`, `sigwait()`, etc.).
[0042] In this embodiment, the pause point is actually the blocked state when the application thread reaches WaitSignal. A thread typically has the following states: ready, running, blocked, and terminated. The operating system usually provides a system interface to allow a thread to wait for a certain signal, and the thread waiting is in a blocked state. A thread in the blocked state does not occupy the CPU, but instead saves its CPU time in the context of the thread control block (TCB), that is, it only occupies a portion of memory and does not incur CPU scheduling overhead.
[0043] At this point, once a corresponding signal is sent to the thread through another application or system, the thread can quickly switch from the blocked state to the running state.
[0044] Therefore, in this embodiment, the operation of the application waiting for a certain signal is encapsulated into an API interface that the PLC application can call. When the PLC application runs to this API, it will be blocked immediately, that is, it will run to the pause point.
[0045] The control system in this embodiment also includes a redundancy management module. This module is connected to both the main controller and the backup controller to perform real-time status monitoring. The monitoring includes the health status of the container environment on the main controller, the health status of the PLC devices inside the container on the main controller, and the network connectivity of the main controller. Based on these parameters, the module determines whether the main controller has malfunctioned. Furthermore, when a malfunction is detected in the main controller or a switching command is received, the system selects the optimal switching target from multiple backup controllers according to a preset weighting strategy. This target is then designated as the new main controller, and a wake-up signal is sent to it to switch the backup controller from a suspended control task execution state to a normal control task execution state. The backup controller then replaces the current main controller to continue executing the control task.
[0046] In this embodiment, the preset weighting strategy is set as follows: when the current main controller fails or a switching command is received, the optimal switching target is selected from multiple backup controllers according to the switching priority value from high to low, and this target is used as the new main controller, and a wake-up signal is sent to it. After the main controller fails, multiple backup controllers are activated sequentially according to the switching priority value, supporting multi-level fault tolerance. This is suitable for critical production lines or unattended operation scenarios, effectively improving the system's survivability in multi-failure scenarios. At the same time, by introducing a backup controller selection mechanism based on priority value calculation, it supports dynamic determination of the switching target based on equipment status, performance indicators, or user policies, thereby improving the system's intelligence level and reliability.
[0047] In this embodiment, each backup controller is configured with a corresponding switching priority value, which is calculated according to the following formula: Y = aX1 + bX2 + cX3 + dX4 + eX5; In the formula, Y represents the corresponding switching priority value configured for each standby controller; X1 is the device performance score for the backup controller; X2 is the current network latency rate of the backup controller; X3 represents the current load rate of the standby controller; X4 represents the historical stability score of the backup controller; X5 is a score for the user selection strategy of the backup controller; a, b, c, d, and e are the weighting coefficients corresponding to the backup controller's device performance score, current network latency, current load rate, historical stability score, and user selection strategy score, respectively.
[0048] like Figure 1 As shown, in one specific embodiment: The production line is equipped with three PLC devices that support real-time Linux (PLC device A, PLC device B, and PLC device C), and all three PLC devices are installed with an ECS real-time container environment. The main controller M runs on PLC device A; Backup controllers S1 and S2 are deployed on PLC device B and PLC device C respectively; After initialization, the standby controllers S1 and S2 enter the control task suspension execution state, with the CPU utilization rate approaching 0%, but they still receive synchronous operation status data from the main controller M. The switching priority value of the backup controller S1 is set to 90 and the switching priority value of the backup controller S2 is set to 70 through the redundancy management module. When PLC device A fails, the redundancy management module detects that the main controller M is out of contact and immediately sends a wake-up signal to the backup controller S1. After receiving the wake-up signal, the backup controller S1 is released from the suspended state and switches from the control task suspended execution state to the control task normal execution state. After resuming execution, it replaces the current main controller to take over control and continues to execute the control task. If the backup controller S1 subsequently fails, the system will automatically switch to the backup controller S2.
[0049] [Second Embodiment] like Figure 2 As shown, the second embodiment of the present invention also provides a control method for a PLC one-master-multiple-standby redundant control system mentioned in the first embodiment, including the following steps: S100: Deploys a pre-defined real-time container environment for multiple PLC devices; S200: Deploy one main controller and multiple backup controllers on the same or different PLC devices and run them in an operating environment that meets preset requirements; S300: Keeps the main controller and the standby controller periodically synchronized in terms of operating status data; S400: The main controller is in the normal execution state of the control task, and the backup controller is in the suspended execution state of the control task. S500: The redundancy management module performs real-time status monitoring of the main controller and the backup controller. When the current main controller fails or a switching command is received, the optimal switching target is selected from multiple backup controllers according to the preset weight strategy and used as the new main controller. A wake-up signal is sent to the backup controller to switch the control task from the suspended execution state to the normal execution state, and the backup controller replaces the current main controller to continue to execute the control task.
[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
Claims
1. A PLC one-master-multiple-standby redundant control system, characterized in that: The system includes: Multiple PLC devices, each of which has real-time processing capability, and each of which is equipped with a preset real-time container environment; The system comprises one main controller and multiple backup controllers, both operating in a pre-defined environment, and deployed on the same or different PLC devices. The main controller and the backup controller maintain synchronized operating status data; The main controller is in a normal control task execution state; The backup controller is in a control task suspended execution state, and immediately switches from the control task suspended execution state to the control task normal execution state after receiving a wake-up signal; The redundancy management module is connected to both the main controller and the backup controller to monitor their real-time status. When the main controller fails or a switching command is received, the module selects the optimal switching target from multiple backup controllers based on a preset weighting strategy. It then sends a wake-up signal to the backup controller to switch it from a suspended control task execution state to a normal control task execution state. Finally, the backup controller replaces the current main controller to continue executing the control task.
2. The PLC one-master-multiple-standby redundant control system according to claim 1, characterized in that: Each of the aforementioned PLC devices is equipped with an ECS real-time container environment.
3. The PLC one-master-multiple-standby redundant control system according to claim 1, characterized in that: The operating environment that meets the preset requirements includes an operating environment that meets the preset standards.
4. The PLC one-master-multiple-standby redundant control system according to claim 1, characterized in that: When the backup controller is in the control task suspended execution state: 1) The backup controller does not participate in CPU time slice allocation and its CPU utilization rate is 0%; 2) The backup controller stores the complete memory context and I / O mapping.
5. A PLC one-master-multiple-standby redundant control system according to claim 1, characterized in that: Upon receiving a wake-up signal, the backup controller immediately switches from the control task suspension execution state to the control task normal execution state, and then resumes the control task from the most recently updated pause point.
6. A PLC one-master-multiple-standby redundant control system according to claim 5, characterized in that: Each of the backup controllers is provided with a pause point, which maintains a signal connection with the main controller through a signal waiting interface.
7. A PLC one-master-multiple-standby redundant control system according to claim 6, characterized in that: The synchronization of operating status data between the main controller and the backup controller includes: The main controller synchronizes its key operating status data to each backup controller via a communication link through a synchronization program in an event-triggered manner. Each backup controller updates its key operating status data when the control task is suspended and synchronizes the updated key operating status data to the pause point through the corresponding signal waiting interface. The new main controller then obtains the last synchronized data from the pause point and begins the current cycle. The key operational status data includes at least variable area snapshots, program counters, and timer status data.
8. A PLC one-master-multiple-standby redundant control system according to claim 1, characterized in that: Each of the aforementioned backup controllers is configured with a corresponding switching priority value, which is calculated according to the following formula: Y = aX1 + bX2 + cX3 + dX4 + eX5; In the formula, Y represents the corresponding switching priority value configured for each standby controller; X1 is the device performance score for the backup controller; X2 is the current network latency rate of the backup controller; X3 represents the current load rate of the standby controller; X4 represents the historical stability score of the backup controller; X5 is a score for the user selection strategy of the backup controller; a, b, c, d, and e are the weighting coefficients corresponding to the backup controller's device performance score, current network latency, current load rate, historical stability score, and user selection strategy score, respectively.
9. A PLC one-master-multiple-standby redundant control system according to claim 8, characterized in that: The preset weighting strategy is set as follows: when the current main controller fails or a switching command is received, the optimal switching target is selected from multiple backup controllers according to the switching priority value from high to low, and a wake-up signal is sent to it.
10. A control method for a PLC one-master-multiple-standby redundant control system according to any one of claims 1-9, characterized in that: Includes the following steps: S100: Deploys a pre-defined real-time container environment for multiple PLC devices; S200: Deploy one main controller and multiple backup controllers on the same or different PLC devices and run them in an operating environment that meets preset requirements; S300: Keeps the main controller and the standby controller periodically synchronized in terms of operating status data; S400: The main controller is in the normal execution state of the control task, and the backup controller is in the suspended execution state of the control task. S500: The redundancy management module performs real-time status monitoring of the main controller and the backup controller. When the current main controller fails or a switching command is received, the optimal switching target is selected from multiple backup controllers according to the preset weight strategy and used as the new main controller. A wake-up signal is sent to the backup controller to switch the control task from the suspended execution state to the normal execution state, and the backup controller replaces the current main controller to continue to execute the control task.