Oversampled Data Frame Compression for PLC Control Transfer
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Solution Overview
Problem
The existing data transfer methods in control systems, such as those using programmable logic controllers (PLCs), face challenges with large data sizes due to oversampling, leading to increased communication and processing burdens.
Innovation Solution
A data transfer device that compresses sampling data by storing only the first sampling data at full size and subsequent data at a compression size sufficient to represent the maximum change between sampling processes, reducing the overall data frame size transmitted to the PLC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oversampling is executed to improve control accuracy, then measurement precision is improved, but data size of data frame becomes large
Solution Approach 1:
The patent segments the data transmission by separating the first sampling data (transmitted at full resolution) from subsequent sampling data (transmitted at compressed resolution). This segmentation allows the system to maintain measurement precision for the initial measurement while reducing data size for subsequent measurements, thereby resolving the contradiction between control accuracy and data size.
Solution Approach 2:
The patent changes the data representation parameter by transmitting subsequent sampling data in a compressed format that represents the maximum change value rather than the full measurement value. This parameter change reduces the data size while preserving the essential information needed for control accuracy, thus resolving the contradiction between measurement precision and data quantity.
2Loss of information
If full-size sampling data is transmitted for each sampling process, then data completeness is improved, but communication burden increases
Solution Approach 1:
The patent extracts only the essential information from subsequent sampling data - specifically the maximum change value - and transmits this compressed representation instead of the full data. This extraction approach maintains data completeness for control purposes while significantly reducing the communication burden by transmitting only the necessary information.
3Quantity of substance
If compression is applied to subsequent sampling data, then data size is reduced, but data processing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and transmitting the maximum change value in the compressed data format. This approach simplifies the overall processing complexity because the compression logic is predetermined and the receiving system only needs to perform simple decoding and reconstruction operations, rather than complex real-time analysis.
Data Source
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AI summary
The present invention suppresses the data size of a data frame to be transmitted to a control device at every control period even if oversampling is performed. A counter unit (10) compresses the data size of sampling data (Sd) indicating a second or subsequent count value (Ct) to the number of bits by which the maximum (Vmax) of a count value countable in one sampling processing can be represented.