Programmable Controller Data Access Rules
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Solution Overview
Problem
Existing programmable logic controllers require changes to the content of original sequence programs when modifying or sharing data with customized programs, limiting data sharing flexibility.
Innovation Solution
A programmable controller with a first and second data storage unit, a rule setting unit for access rules, and a program executing unit that executes sequence programs while adhering to these rules, allowing data sharing without modifying the original program's content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a general data management method is used to share data between original program and modified program, then data sharing is enabled, but the content of the original program must be changed
Solution Approach 1:
The data storage is segmented into first data storage unit (for original program) and second data storage unit (for modified program). The rule setting unit segments access permissions by creating access rules that define which programs can access which data storage units. This segmentation allows data sharing while maintaining program independence, as the original program continues to access only the first data storage unit without modification.
Solution Approach 2:
The rule setting unit acts as an intermediary that manages access between the original program and modified program to shared data storage units. It creates and enforces access rules that allow the modified program to access the first data storage unit while preventing the original program from being modified. This intermediary mechanism enables data sharing without requiring changes to the original program content.
2Adaptability or versatility
If the shared data storage unit definition is modified to accommodate changes in the second sequence program, then data access flexibility is improved, but the first sequence program must be modified
Solution Approach 1:
The system dynamically adjusts access permissions through the rule setting unit rather than modifying program content. When the second sequence program needs to access data in the first data storage unit, the rule setting unit dynamically creates or modifies access rules to permit this access. This dynamic permission management provides data access flexibility while keeping the original program's composition stable and unchanged.
Solution Approach 2:
The solution adds a new dimension of access control by introducing the rule setting unit and access rules layer between programs and data storage units. Instead of modifying the original program's data storage definitions, the system manages access permissions in this additional dimensional layer, allowing flexible data access without affecting the stability of the original program's internal structure.
3Adaptability or versatility
If multiple sequence programs share the same data storage unit, then data sharing is achieved, but access control and unexpected operations become problematic
Solution Approach 1:
The rule setting unit applies local quality control by creating specific access rules for each program-data storage unit combination. Each rule locally defines whether a specific program can read or write to a specific data storage unit. This localized access control ensures that the original program maintains reliable execution by preventing unauthorized access or modifications to its data storage unit, while still allowing controlled sharing with the modified program.
Data Source
AI summary
A programmable controller sets access rules relating to permission or denial of access to a first data storage unit during execution of a second sequence program. In addition, a first sequence program is executed while accessing only the first data storage unit, whereas the second sequence program is executed while accessing the first data storage unit and a second data storage unit in accordance with the set access rules.