PLC Program Safety Barrier Search for Fault Tree Consistency
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Solution Overview
Problem
Technicians face significant time and effort in extracting events causing undesired events in plant control programs, and maintaining consistency between fault tree analysis and program logic is challenging due to modifications in the PLC program.
Innovation Solution
An analysis assistance apparatus and method that obtain control programs, extract event information, and search for safety barriers by identifying causal relationships between input and output variables, automating the process of finding safety barriers within the control program.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a technician manually analyzes PLC program code to extract events causing undesired events, then the fault tree analysis can be performed, but the task requires an enormous amount of time and effort
Solution Approach 1:
The patent replaces the manual mechanical analysis process with an automated computer-based system. The analysis assistance apparatus automatically extracts events causing undesired events by processing PLC program code through software algorithms, eliminating the need for technicians to manually analyze program code while maintaining analysis accuracy.
Solution Approach 2:
The system enables self-service by allowing the fault tree analysis process to perform its own data extraction automatically. The analysis assistance apparatus independently identifies events and causal relationships from the PLC program without requiring continuous human intervention, making the system self-sufficient in the analysis task.
2Reliability
If fault tree analysis is performed manually, then the initial analysis can be completed, but inconsistencies may be created when PLC program is modified requiring re-analysis
Solution Approach 1:
The patent implements feedback by continuously monitoring PLC program modifications and automatically updating the fault tree analysis. When the PLC program is modified, the analysis assistance apparatus detects the change, re-extracts relevant events, and updates the fault tree to maintain consistency between the analysis and current program logic.
Solution Approach 2:
The system transforms the static fault tree analysis into a dynamic process that automatically adapts to program changes. The analysis assistance apparatus continuously synchronizes with PLC program modifications, making the fault tree analysis flexible and responsive to system changes rather than requiring manual re-analysis.
3Reliability
If manual extraction of events from PLC program code is performed, then safety barriers can be identified, but the process is time-consuming and labor-intensive
Solution Approach 1:
The patent replaces manual extraction of safety barrier information with automated computer-based processing. The analysis assistance apparatus uses software to systematically identify and extract safety barriers from PLC program code, maintaining accuracy while dramatically improving productivity by eliminating manual labor in the extraction process.
Data Source
AI summary
An analysis assistance apparatus 10 includes: a control program obtainment unit 11 that obtains a control program of a plant based on sensor data from a sensor installed in the plant; an event information obtainment unit 12 that obtains event information, which includes a variable that defines a state of the plant when a predetermined event has occurred and a value thereof, as information necessary for searching the control program for a safety barrier for avoiding the occurrence of the predetermined event in the plant; and a safety barrier search unit 13 that extracts, from the control program, a causal relationship between an input variable and an output variable, and searches the control program for the safety barrier based on the variable and the value included in the event information and on the extracted causal relationship.