PLC Variable Monitoring for Real-Time State Change Diagnostics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current monitoring systems for industrial installations driven by programmable controllers are inefficient in tracking the evolution of internal variables in real-time, leading to unpredictable behaviors, incorrect data calculations, and loss of information, as they require external analysis systems that are complex, costly, and often unable to detect fugitive variable changes within a cycle turn.
Innovation Solution
Implementing specific monitoring modules within the user program of the programmable controller to read and record the logic state of variables in real-time, comparing previous and current states, and time-stamping changes, allowing for accurate metadata collection and analysis of variable evolutions, which can be visualized graphically for easy interpretation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external analysis systems are used to monitor controller variables, then monitoring capability is provided, but device complexity and cost increase significantly
Solution Approach 1:
The monitoring functionality is merged directly into the controller by integrating a monitoring module within the controller's memory and processing units. This allows the controller to monitor its own variables without requiring external analysis systems, thereby reducing device complexity and cost while maintaining monitoring precision.
Solution Approach 2:
The controller performs self-monitoring through an integrated monitoring module that automatically tracks variable states, detects changes, and generates alerts without external intervention. This self-service approach eliminates the need for complex external monitoring systems while providing continuous variable surveillance.
2Loss of information
If external analysis systems continuously query the controller, then variable evolution is tracked, but controller resources are overloaded and response times increase
Solution Approach 1:
The monitoring module operates autonomously within the controller, independently tracking variable states and detecting changes without requiring external queries. This eliminates the overhead of continuous external communication and preserves controller response times while maintaining complete variable evolution tracking.
Solution Approach 2:
The monitoring module proactively detects variable state changes as they occur during normal controller operation, rather than waiting for external systems to query for updates. This preliminary detection mechanism ensures no information is lost while minimizing interference with controller productivity.
3Measurement precision
If monitoring is implemented to detect variable changes, then diagnostic accuracy improves, but controller cycle time increases
Solution Approach 1:
The monitoring module uses event-driven periodic action, actively checking for variable state changes only at relevant points during the controller cycle rather than continuously monitoring all variables. This approach maintains high diagnostic accuracy by detecting all state changes while minimizing the time added to controller cycle time.
Solution Approach 2:
The monitoring functionality is selectively applied to specific variables and program locations where state changes are most critical for diagnostics. This localized monitoring approach provides high diagnostic accuracy for key variables without the overhead of monitoring all variables throughout the entire program, thus preserving controller cycle time.
Data Source
AI summary
A method of monitoring and assessing program variables of an industrial installation driven by a controller (C) by instructions programmed in a user program. Specific monitoring modules (MS1 to MSt) are implanted, as close as possible in time to the variable(s) (V1 to Vt) to be monitored to monitor evolution in real-time. During execution, each specific monitoring module (MSy) reads, in real-time, the logic state of each of variables which it monitors in an instantaneous cycle turn (TCi) of the controller (C), compares this logic state with the previously recorded logic state, and, only in the case of a state change, records the new logic state read as well as the real-time time-stamp of this event in a global memory unit (UM_G). The recorded metadata is analyzed in order to check behavior of the installation, use this production data and identify a possible malfunction of program and/or the installation.