PLC Control Device Soft Error Handling
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Solution Overview
Problem
Existing control devices with programmable logic controllers (PLCs) often experience unnecessary shutdowns due to soft errors in configuration RAM, which can occur in unused portions of the programmable circuit, leading to inefficiencies and reduced reliability, as current surveillance control circuits cannot differentiate between errors affecting functional units and those that do not.
Innovation Solution
A control device with a programmable circuit unit and arithmetic processing unit that uses a cyclic redundancy check (CRC) to detect soft errors and determines the affected functional unit, allowing for selective shutdown or degeneration operations to prevent unnecessary stops, thereby maintaining system reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a surveillance control circuit is provided to detect soft errors in the CRAM, then the reliability of error detection is improved, but the control device stops unnecessarily even when the soft error is at a position unrelated to a functional unit
Solution Approach 1:
The patent segments the CRAM into multiple blocks and further divides each block into word lines and bit lines, enabling localized error detection and isolation. When a soft error is detected in a specific block, only that block is invalidated rather than stopping the entire device, thus maintaining productivity while ensuring reliable error detection.
Solution Approach 2:
The patent implements local quality by applying error detection and correction mechanisms specifically to affected blocks rather than the entire CRAM. The system determines whether a soft error affects a functional unit by examining the specific block and word line where the error occurred, allowing selective continuation of unaffected functional units.
2Reliability
If the control device stops when a soft error is detected in the CRAM, then the reliability of the control device is improved, but unnecessary stops occur when the soft error does not affect the function of the control device
Solution Approach 1:
The patent implements dynamic error handling by continuously monitoring CRAM blocks and adaptively responding to soft errors. When a soft error is detected, the system dynamically determines whether to stop the entire device or only specific functional units based on the error's impact, allowing the control device to maintain operation whenever possible and thus reducing operational downtime.
Solution Approach 2:
The patent converts the harmful effect of soft errors into a beneficial selective shutdown mechanism. By detecting the specific location and impact of soft errors, the system can isolate only the affected functional units while keeping the rest of the device operational, thereby transforming potential complete downtime into minimal or no downtime.
3Adaptability or versatility
If a programmable circuit unit with CRAM is used, then the adaptability of the control device is improved, but the susceptibility to soft errors increases
Solution Approach 1:
The patent implements preliminary error detection and correction mechanisms within the CRAM structure itself. Error detection circuits are built into each block before operation, and correction codes are预先 calculated and stored. When a soft error occurs, the system can immediately detect and correct it without affecting the adaptability of the programmable circuit unit.
Solution Approach 2:
The patent provides beforehand cushioning against soft errors by implementing redundant storage elements and error correction codes in the CRAM. These protective measures are built into the structure of the programmable circuit unit, cushioning against the harmful effects of soft errors while preserving the adaptability and reconfigurability of the device.
Data Source
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AI summary
The invention provides a control device capable of preventing unnecessary stop in the control device including a programmable circuit unit (20) and an arithmetic processing unit (10), and a method of controlling the control device. In the invention, an abnormality determination unit (15) determines a correspondence between a position of a soft error detected by an error detection unit and a functional unit (22) based on map information including position information (position number) in the programmable circuit unit (20). Further, a processor unit continues operating the control device when the abnormality determination unit determines the position of the soft error corresponds to an unused portion of the functional unit, and executes a predetermined process when the abnormality determination unit determines the position of the soft error corresponds to a used portion (e.g. a majority circuit unit or a used circuit unit) of the functional unit.