Redundant Automation Synchronization for Uninterrupted PLC Updates
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Solution Overview
Problem
Conventional redundant automation systems face challenges in maintaining uninterrupted data capture and synchronization during the coupling and updating phase, leading to potential data loss and complex temporary storage requirements.
Innovation Solution
The system employs first and second data reconciliators to transfer and backup static configuration data, and to incrementally read and write dynamic runtime data between subsystems, ensuring synchronized write access and minimizing data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If write access to persistent data is locked during the sync-up procedure, then data consistency between subsystems is ensured, but data capture becomes interrupted and complex temporary storage is required
Solution Approach 1:
The patent segments the data synchronization process into two independent program units: one handling control program execution and another handling data transfer. This segmentation allows write access to be locked for the data transfer unit while the control program unit continues executing without interruption, thus maintaining data consistency while preserving uninterrupted data capture capability.
Solution Approach 2:
The patent introduces an intermediary mechanism where the data reconciliator acts as a mediator between the control program and the file system. During the coupling and updating phase, the data reconciliator manages the locking and unlocking of write access, coordinating between the master and slave PLCs to ensure consistency without requiring the entire system to stop data capture.
2Reliability
If all status-relevant data is transferred from the running PLC to the new PLC during coupling and updating, then the new subsystem is synchronized, but the transfer process is time-consuming and disrupts process control
Solution Approach 1:
The patent applies preliminary action by having the control program continuously write status information to the persistent data file before the coupling and updating phase begins. This pre-positioning of data in the file system allows the new PLC to quickly synchronize by reading the already-prepared data, rather than transferring data in real-time during the coupling phase, thus reducing the time required.
Solution Approach 2:
The patent maintains continuity of useful action by allowing the control program to continue executing and writing status information throughout the coupling and updating phase. The data transfer operation runs concurrently with the control program execution, ensuring that data capture continues without interruption and synchronization is achieved more quickly.
3Reliability
If the control program is stopped during the update procedure, then data consistency is maintained, but productivity decreases and the process control is disrupted
Solution Approach 1:
The patent segments the system operations into independent program units that can execute concurrently. The control program unit continues running and processing process control tasks, while the data transfer unit handles the synchronization operations. This segmentation eliminates the need to stop the entire control program, maintaining productivity while ensuring data consistency through controlled access in the data transfer unit.
Data Source
AI summary
A redundant automation system includes a first and a second identically configured subsystems, which each have a control program for controlling a technical process, wherein a synchronization connection is between the first and second subsystems, saved in the first subsystem in a source file is status information including static configuration data and dynamic runtime data, in order to enable uninterrupted updates of the second subsystem, a first data reconciliator is configured with a first independent program unit that is configured to incrementally read out write accesses of dynamic runtime data of the first subsystem to the source file to update the dynamic runtime data of the second subsystem and to transfer data contents of repeat write accesses to the second subsystem, and a second data reconciliator is configured with a second independent program unit configured to incrementally receive the repeat write accesses and subsequently storing them in a target file.