Safety Control Data Refresh During Control Program Changes

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Solution Overview

Problem

Conventional safety control units in FA systems temporarily stop all programs and data refresh when subjected to external program changes, leading to unnecessary stops in safety control.

Innovation Solution

A safety control unit that continues data refresh during control program changes by executing a part of the system program, including a data refresh program, allowing uninterrupted safety control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the computation control part stops executing all programs including data refresh when receiving a control program change, then the control program can be changed safely, but the safety control stops unnecessarily

Engineering Contradiction:

Improvesafety control continuityVSAvoidprogram change capability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system program is segmented into two independent parts: the data refresh program that continues executing to maintain safety control, and the control program that is stopped and replaced. This segmentation allows the data refresh operation to proceed independently while the control program is being changed, resolving the contradiction between maintaining safety control continuity and enabling program changes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The data refresh program continues to execute continuously during control program changes, ensuring that safety control data is constantly updated and safety control remains active. This continuous execution of the useful data refresh action prevents the unnecessary stop of safety control while allowing the control program to be changed.

Inventive Principle:

Principle #20Continuity of useful action

2Productivity

If the computation control part continues executing all programs including data refresh when receiving a control program change, then safety control continues, but the control program cannot be changed properly

Engineering Contradiction:

Improvesafety control continuityVSAvoidprogram change reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system program is divided into the data refresh program and the control program as separate executable entities. This segmentation enables the data refresh program to continue executing while the control program is stopped and replaced, ensuring both the reliability of program changes and the continuity of safety control.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of stopping or continuing all programs entirely, the system applies partial action by selectively stopping only the control program while allowing the data refresh program to continue. This partial execution approach resolves the contradiction by applying the appropriate level of action to each program component.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS10935935B2Safety control unit, safety control method, and safety control program

Publication Date: 2021.03.02 OMRON CORP

AI summary

A safety control unit includes: a memory; a computation control part; and an input and output unit for connecting the computation control part to a safety input device and an output device to be safely controlled. A system program includes a data refresh program for executing a data refresh of safety control data of the safety input device and the output device and the control data of the memory via the input and output unit. If the computation control part receives a change of a control program, the computation control part stops executing the control program. The computation control part executes the change of the control program while executing a part of the system program including the data refresh. The computation control part resumes executing the control program.