Shared-Memory PLC Control for Real-Time Program Updates

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Solution Overview

Problem

Conventional distributed monitoring control systems are expensive and inflexible due to their manufacturer-specific, dedicated appliance design, and existing technologies do not allow for seamless integration of general-purpose appliances, which limits scalability and functionality, particularly in controlling industrial processes where delays can lead to unstable operations.

Innovation Solution

A control apparatus that coexists with both control programs and information programs on the same platform, allowing for flexible program changes such as addition, deletion, or update without stopping the control program or delaying scan operations, using a shared area for information exchange and resource management to ensure real-time processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dedicated appliances are used for control systems, then control reliability is improved, but device complexity and cost increase

Engineering Contradiction:
Improvecontrol reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines control programs and information programs on the same platform (programmable logic controller), merging previously separate dedicated control systems with information processing systems. This integration allows general-purpose appliances to perform both control and information processing functions, reducing device complexity and cost while maintaining control reliability through proper program separation and execution management.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent enables the programmable logic controller to execute multiple types of programs (control programs and information programs) on the same platform, making it a universal device that can handle both real-time control tasks and general information processing. This multi-functionality eliminates the need for separate dedicated control appliances and general-purpose computers, reducing overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Stability of the object's composition

If dedicated appliances are used for control systems, then control stability is improved, but adaptability deteriorates

Engineering Contradiction:
Improvecontrol stabilityVSAvoidadaptability
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent segments programs into control programs (requiring real-time execution and high stability) and information programs (allowing flexible changes). This segmentation allows control programs to maintain stable execution on the same platform while information programs can be freely added, deleted, or updated, providing adaptability without compromising control stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

By making the programmable logic controller a universal platform that accepts both control and information programs, the system gains adaptability to perform various functions while maintaining control stability through the prioritized execution of control programs.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If program changes are made in control systems, then functionality is improved, but control performance deteriorates

Engineering Contradiction:
ImprovefunctionalityVSAvoidcontrol performance
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent divides the system into control programs that maintain real-time performance and information programs that provide functional flexibility. Control programs continue to execute with high priority and deterministic timing, while information programs can be changed freely without affecting control performance, as they run with lower priority or during idle cycles.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic program management where the controller can load, unload, and update information programs during operation without stopping control programs. This dynamic capability allows functionality to be changed on-the-fly while control performance is maintained through priority-based execution and proper resource management.

Inventive Principle:
Principle #15Dynamics

4Ease of manufacture

If general-purpose appliances are used, then cost is reduced, but control reliability deteriorates

Engineering Contradiction:
ImprovecostVSAvoidcontrol reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent merges control functions and information processing functions into a single general-purpose programmable logic controller platform. This allows the use of cost-effective general-purpose appliances instead of expensive dedicated control systems, while maintaining control reliability through software-based program separation and execution prioritization.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the operational parameters of the general-purpose appliance by implementing a program execution management system that allocates CPU time, memory, and I/O resources differently for control programs versus information programs. This parameter management ensures that control programs receive sufficient resources to maintain reliability while the general-purpose platform provides cost benefits.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3779622B1Control device
Publication Date: 2022.10.05 HITACHI IND EQUIP SYST CO LTD
  • EP3779622B1 patent drawingFigure 1
  • EP3779622B1 patent drawingFigure 2
  • EP3779622B1 patent drawingFigure 3

AI summary

A control apparatus where control programs and information programs coexist is allowed to change programs flexibly. Not only one or more control programs but also one or more information programs are installed in the control apparatus, which is provided with a shared area. The shared area is an area that at least one control program and at least one information program can access. Shared information is stored in the shared area. The shared information includes at least one of information related to an I/O port accessed by the control programs, and information related to the control program. Each control program is a program that performs scan operation of outputting control information on the relevant control object apparatus coupled to the I/O port accessed for controlling a control object apparatus with respect to the control program, to this I/O port. Each information program is a program that performs information processing that does not include the scan operation.