PLC Process Data Logging with Thread Pool Hash Tables
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Solution Overview
Problem
Existing logging techniques for PLC-controlled equipment are inefficient and resource-intensive, often resulting in only a fraction of generated data being logged, and suffer from complexity and jitter issues, hindering the improvement of complex systems like filling machines.
Innovation Solution
A method that assigns process values from PLC application code tasks with different execution rates to threads in a thread pool, using a hash function to arrange tag and process values in data tables, enabling parallel and efficient logging of process data across various execution rates and domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If manual logging solutions are used to log process data from PLC tasks with different execution rates, then logging coverage can be increased, but system complexity and resource consumption increase unreasonably
Solution Approach 1:
The logging system segments PLC tasks into groups based on their execution rates, with each group handled by a dedicated thread in a thread pool. This segmentation allows the system to manage multiple execution rates simultaneously without requiring complex custom implementation for each task, thereby increasing logging coverage while controlling system complexity through structured organization.
Solution Approach 2:
The patent implements a universal logging infrastructure that can handle multiple PLC tasks with different execution rates through a common thread pool architecture. This multi-functional system replaces multiple specialized manual logging solutions, providing comprehensive logging coverage across all task types while reducing overall system complexity through standardization.
2Productivity
If stand-alone logging solutions are implemented to provide automated logging process, then logging efficiency improves, but implementation complexity and resource requirements increase
Solution Approach 1:
The patent merges the logging functionality directly into the existing PLC control system by utilizing the PLC's task execution framework and integrating a thread pool that works seamlessly with PLC tasks. This integration eliminates the need for separate stand-alone logging systems, maintaining high logging efficiency while reducing implementation complexity by leveraging existing infrastructure.
Solution Approach 2:
The logging system is designed to automatically adapt to different PLC task execution rates without requiring manual configuration or customization for each application. The thread pool automatically adjusts to the execution rates of assigned tasks, enabling self-service operation that maintains high logging efficiency while minimizing the resources needed for setup and maintenance.
3Loss of energy
If existing logging techniques are used to log process data, then resource consumption is reduced, but logging stability and completeness deteriorate due to jitter
Solution Approach 1:
The patent introduces a thread pool as an intermediary layer between PLC tasks and the logging mechanism. This intermediary manages the timing and execution of logging operations, buffering the direct interaction between tasks of different execution rates and the logging system. This mediation eliminates jitter by decoupling the logging operations from the varying execution rates, ensuring stable and complete logging while maintaining efficient resource consumption.
Data Source
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AI summary
A method of logging process data in a PLC controlled equipment is disclosed. Sections of a PLC application code comprise tasks configured to execute program functions at specific execution rates. Each of the tasks comprise program functions having dedicated memory areas assigned as tags, and each data entry of the process data comprises a tag value and an associated process value. The method comprises receiving process data from the PLC application code, assigning process values to threads of a thread pool, and receiving, for each of the threads, in a respective data table associated with each of the threads, the tag- and process values of the received process data, and determining a hash code for each of the tags according to a hash function of the respective data table for arranging the tag values and the associated process values in the respective data table according to said hash code.