HMI Data Mirroring Across Dual OS to Prevent Disk Wear
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Solution Overview
Problem
In process control systems, existing methods for mirroring human machine interface (HMI) data are prone to data loss and disk life issues due to frequent writing, especially during power interruptions, when using general-purpose operating systems without non-volatile memory like MRAM.
Innovation Solution
A controller and data storage method utilizing a dedicated operating system with a real-time OS and hypervisor to perform mirroring processing, storing HMI data in volatile memory and non-volatile memory, reducing disk load and extending disk life by writing data at appropriate timings and during power interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HMI data is flushed to disk for each input to prevent data loss, then data reliability is improved, but disk life deteriorates due to high-frequency writing
Solution Approach 1:
The patent introduces a buffer memory as an intermediary between the HMI data input and the disk storage. Data is first written to the buffer memory at high frequency without affecting disk life, and then periodically transferred to the disk at lower frequency. This mediator absorbs the high-frequency writing operations, preventing direct impact on disk longevity while ensuring data is preserved.
Solution Approach 2:
The system performs preliminary action by writing HMI data to the buffer memory in advance before transferring to the disk. This preliminary storage in volatile memory ensures data is captured immediately at high frequency, and the subsequent transfer to disk occurs at an optimized lower frequency, thus protecting disk life while maintaining data reliability.
2Duration of action of stationary object
If HMI data is flushed to disk at appropriate timings to extend disk life, then disk life is improved, but data loss risk increases during power interruptions
Solution Approach 1:
The patent implements beforehand cushioning by maintaining a buffer memory that continuously holds HMI data before disk transfer. This buffer acts as a cushion that protects against data loss during power interruptions - even if data hasn't been transferred to the disk yet, it remains safely stored in the buffer memory, preventing data loss while allowing disk writing to occur at extended intervals.
Solution Approach 2:
The system creates a copy of HMI data in the buffer memory before transferring to the disk. This copying mechanism ensures that the original data is preserved in the buffer while a copy is stored on the disk at optimized intervals. During power interruptions, the buffered copy ensures no data is lost, while the disk experiences reduced writing frequency.
3Device complexity
If a general-purpose operating system is used without non-volatile memory, then system complexity is reduced, but robustness against power failure deteriorates
Solution Approach 1:
The patent employs volatile buffer memory (cheap, short-living storage) instead of expensive non-volatile memory like MRAM to achieve robustness against power failure. The volatile memory is readily available and inexpensive, and while it loses data on power loss, the system compensates by implementing frequent buffer-to-disk transfers and maintaining redundant data copies, thus achieving reliability without requiring expensive non-volatile memory components.
Data Source
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AI summary
In the disclosure, HMI data is mirrored under high robustness. An IPC (3) operates in an OS (41) and a real time OS (51). The IPC (3) includes a data managing part (411) that sequentially performs acquisition processing of the HMI data by an HMI application (412) of the OS (41), a buffer (413) memorizing the HMI data by the data managing part (411), a data managing part (511) that exchanges data with the data managing part (411) by a mirroring processing part (52) of the real time OS (51), and a mirroring data holding part (513) memorizing data by the data managing part (511). The data managing part (411) memorizes the HMI data in the buffer (413) for each acquisition of the HMI data and transmits the HMI data to the data managing part (511) as mirroring data, the data managing part (511) memorizes the mirroring data in the mirroring data holding part (513) for each reception of the mirroring data.