PLC Variable Synchronization for Ladder and Motion Control
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Solution Overview
Problem
In programmable logic controllers (PLCs) using multi-core processors, the management of data interchange between ladder programs and motion control becomes complicated, leading to potential control errors due to variable synchronization issues.
Innovation Solution
A programmable logic controller with a first core for control logic operations and a second core for motion control, along with a management unit and synchronization control units, ensures sequential execution and synchronization of variable groups to facilitate efficient management of user programs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multi-core processor is used to execute ladder programs and motion control in a distributed manner, then processing performance improves and mutual interference is reduced, but data interchange management becomes complicated
Solution Approach 1:
The patent divides the variable storage into separate variable groups (first variable group for control logic, second variable group for motion control) that are managed independently by each core. This segmentation allows each core to access its designated variables without direct interference, simplifying the management of data interchange while maintaining high processing performance.
Solution Approach 2:
The patent introduces a management unit that acts as an intermediary between the first core and second core. This management unit coordinates data interchange by controlling access to shared resources and managing the execution timing of both cores, thereby reducing the complexity of direct data interchange management while preserving the performance benefits of multi-core processing.
2Productivity
If data read and write operations are performed by both control logic execution and motion control simultaneously, then processing efficiency improves, but synchronization errors may occur
Solution Approach 1:
The patent implements periodic refresh processing where the management unit sequentially executes the first core's control logic and performs refresh processing of the first variable group at regular intervals. This periodic execution pattern ensures that data synchronization occurs at predictable timing points, maintaining both processing efficiency and synchronization accuracy.
Solution Approach 2:
The patent performs refresh processing of the first variable group in advance before the second core accesses the data. By preliminarily updating the variable group that will be shared between cores, the system ensures that motion control operations always read consistent, up-to-date data, preventing synchronization errors while maintaining efficient parallel processing.
Data Source
AI summary
To facilitate management of execution of a user program such as a ladder program and motion control. A processor includes a first core that executes a control logic operation based on a user program and a second core that executes motion control based on the user program. A memory stores a first variable group accessed when the control logic operation is executed by the first core and a second variable group accessed when the motion control is executed by the second core. A management unit performs management such that the control logic operation executed by the first core and refresh processing of the first variable group stored in the memory are sequentially executed. A synchronization control unit synchronizes a variable related to the motion control in the first variable group with a corresponding variable in the second variable group through the refresh processing.