Industrial Controller Redundancy via Segmented I/O Tracking
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Solution Overview
Problem
In industrial control systems, the lack of efficient data tracking in multitasking environments leads to inefficiencies and data inconsistencies during controller switchovers, particularly when higher priority tasks preempt lower priority tasks, causing data transfer delays and potential disruptions in the controlled process.
Innovation Solution
Implementing a flag table with controller-scoped and program-scoped flags to separately track changes in the I/O data table, allowing for synchronized data transfer only after completion of tasks, thereby decoupling data transfer from other tasks and minimizing disruptions during switchovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single large tracking table is used to track all information in a multitasking environment, then all data changes can be monitored, but it becomes difficult to distinguish between changes made by different processes and higher priority tasks may send changes that lower priority tasks have made, significantly slowing down data transfer to the secondary controller
Solution Approach 1:
The patent divides the single large tracking table into multiple separate tracking tables, with each tracking table dedicated to a specific task or process. This segmentation allows the system to track data changes for each task independently, making it easy to distinguish which task made which changes. When a switchover occurs, only the tracking tables relevant to the active task need to be transferred, significantly reducing data transfer time and eliminating the problem of higher priority tasks sending changes that lower priority tasks have already made.
2Loss of information
If all data changes are tracked as a single group, then comprehensive monitoring is achieved, but one program's data cannot be differentiated from another, causing high priority tasks to become a vehicle for transferring a majority of the data changes and significantly slowing completion time
Solution Approach 1:
The patent segments the tracking mechanism by creating task-specific tracking tables that are associated with individual tasks. Each tracking table records only the data changes made by its associated task, enabling clear differentiation between programs. This allows high priority tasks to transfer only their own data changes rather than being forced to transfer all data changes from lower priority tasks, significantly reducing task completion time while maintaining complete tracking of all data changes across the system.
Solution Approach 2:
The patent implements preliminary organization of data tracking by task before switchover occurs. Each task maintains its own tracking table that is continuously updated with its data changes, so that when a switchover is needed, the secondary controller already has the organized, task-specific tracking information ready for rapid transfer. This preliminary organization eliminates the need for time-consuming data sorting and filtering during critical switchover operations.
Data Source
AI summary
An industrial control system implementing a multi-tasking operating system employs a primary and secondary controller each having a processor and an I/O data table. The processors are configured to execute one or more priority ranked programs. A tracking of changes in the I/O data table of the primary processor is used to independently track changes to controller specific data that has been changed and program specific data that has been changed and to transmit controller specific data that has been changed by any program and program specific data that has been changed only for completed programs to the secondary processor.