Controller Support Apparatus Execution Time Estimation
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Solution Overview
Problem
Conventional methods for estimating the execution time of control programs in PLCs using general-purpose microprocessors are inaccurate due to optimization effects and variable execution times of library functions, leading to poor estimation accuracy.
Innovation Solution
A controller support apparatus that calculates an estimated execution time by using calibration data derived from measuring test execution times at both a simulator and a controller, allowing for more accurate prediction of control program execution times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If actual process time data is accumulated for each command in the control program, then execution time estimation can be obtained, but the estimation accuracy deteriorates due to optimization effects and variable execution times of library functions
Solution Approach 1:
The patent changes the approach from accumulating actual process time data for each command to measuring total execution time of the control program under different execution environments. By obtaining execution time data from both the controller support apparatus (simulator) and the actual controller, and calculating conversion coefficients based on the ratio of these times, the system achieves more reliable estimation that accounts for hardware differences and optimization effects.
2Ease of operation
If execution time is measured at the controller support apparatus simulator, then testing can be performed, but the measured execution time differs from actual controller execution time due to hardware and software environment differences
Solution Approach 1:
The patent introduces conversion coefficients as an intermediary element to bridge the gap between simulator execution time and actual controller execution time. These coefficients are calculated by comparing execution times of the same control program when run on both the controller support apparatus and the actual controller, allowing accurate prediction of controller execution time based on simulator measurements.
Solution Approach 2:
The system performs feedback by actually measuring execution time on the controller to determine conversion coefficients, then using these coefficients to correct and refine subsequent execution time predictions. This feedback loop ensures that the estimation accurately reflects real controller behavior while maintaining the convenience of simulator-based testing.
Data Source
AI summary
A controller support program causes a processor to acquire a first control execution time which is an execution time of a first control program which is an object program generated from a control source program, which is a source program of a control program generated in accordance with an object of control of a user, and operating at the simulator, the first control execution time being measured at the simulator. The processor also calculates an estimated execution time which is an estimated value of an execution time, at the controller, of a second control program which is an object program generated from the control source program and operating at the controller, by converting the first control execution time using the calibration data. Data representing the estimated execution time is output.