PLC Database Response Time Logging for Control System Debugging
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Solution Overview
Problem
Control systems with PLCs connected to database systems face challenges in analyzing delays and inefficiencies, as existing techniques lack efficient methods for measuring and analyzing response times, making it difficult to diagnose and address performance issues.
Innovation Solution
A controller with a communication interface connected to a database system, featuring an access processing unit that generates and transmits statements, measures response times, and stores this information for analysis, allowing for efficient debugging and soundness checking by recording transmission and reception times and displaying this data for further processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PLC accesses the database system to store and retrieve data, then the control system can maintain logs and process data, but the process time becomes longer than assumed and performance deteriorates
Solution Approach 1:
The patent applies preliminary action by recording the statement transmission time before the PLC accesses the database system. This allows the system to pre-capture the starting point of the operation, enabling accurate response time calculation without adding measurement overhead during the actual database access process. The transmission time is recorded in advance in the operation log, so when the response is received, the response time can be immediately calculated by subtracting the pre-recorded transmission time from the current time.
2Productivity
If the control system increases the speed of the control process or improves database response performance, then the process time can be reduced, but the complexity of analyzing and implementing improvements increases
Solution Approach 1:
The patent implements feedback by automatically recording and storing the response time of database operations in the operation log. This creates a feedback mechanism where the system continuously monitors its own performance, providing data that can be analyzed to identify bottlenecks and guide optimization efforts. Instead of requiring complex manual analysis, the system automatically collects performance data, making it easier to identify which aspects of the control process or database operations need improvement.
3Difficulty of detecting and measuring
If the system records detailed information about statement transmission and response reception, then the cause of delays can be analyzed, but the amount of data to be processed and stored increases
Solution Approach 1:
The patent applies the taking out principle by extracting only the essential time-related information needed for performance analysis. Instead of recording all possible details about database operations, the system specifically extracts and records the statement transmission time and response reception time. This selective extraction of critical data points provides sufficient information for delay analysis while keeping the data volume manageable. The operation log stores only these key temporal markers, which can then be used to calculate response times without requiring extensive data processing.
Data Source
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AI summary
This invention provides a technique capable of efficiently performing debugging in a program and checking of soundness in a control system including a controller and a database system. A CPU unit (104) has a communication interface for connection to a database device (400). The CPU unit (104) executes a user program (186) to call a DB connection service in accordance with an instruction included in the user program and generate a statement to access the database device (400). In the DB connection service, a statement according to an access instruction is generated, and the generated statement is transmitted to a database system. After that, information indicative of time until a response from the database system is received is acquired, and the acquired information is stored as a log into a memory. A support device (300) acquires the information and displays it on a monitor.