PLC Serial Communication Mapping for Fast Reconfiguration
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Solution Overview
Problem
Existing programmable logic controllers (PLCs) require significant changes to user programs when the connection position of the communication interface device is altered, leading to inefficiencies in reconfiguration.
Innovation Solution
A programmable logic controller with a memory that stores user programs and setting documents, where user programs record commands and command target information, and setting documents save address information, allowing for minimal changes to the user program when the connection position of the communication interface device is changed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the connection position of the communication interface device is changed, then the adaptability of the system is improved, but the user program has to be rewritten which increases the time required for reconfiguration
Solution Approach 1:
The patent divides the system configuration into two separate parts: the user program containing communication commands and device identifiers, and the setting document containing address information mapping device identifiers to physical connection positions. This segmentation allows the user program to remain unchanged while only the setting document needs updating when connection positions change, thereby resolving the contradiction between adaptability and reconfiguration time.
2Reliability
If the command and command target information are recorded together in the user program, then the completeness of the control logic is improved, but the complexity of modifying the user program increases when connection position changes
Solution Approach 1:
The patent extracts the address information mapping from the user program and places it in a separate setting document. The user program retains only the communication commands and device identifier information, while the mapping between identifiers and physical addresses is stored externally. This extraction maintains the completeness of control logic in the user program while reducing the complexity of modifications when connection positions change.
3Ease of manufacture
If the address information is embedded in the user program, then the integration of control logic is improved, but the ease of reconfiguration deteriorates when communication interface device position changes
Solution Approach 1:
The patent introduces a setting document as an intermediary between the user program and the physical connection configuration. This intermediary layer contains the address information mapping that translates device identifiers in the user program to actual connection positions. By using this intermediary, the system achieves easy reconfiguration (only update the setting document) while maintaining integrated control logic (user program remains unified and complete).
Data Source
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Figure 3a~3b
AI summary
A programmable logic controller (10) is connected to external equipment (40) through a serial communication unit (30), and the programmable logic controller (10) includes: a memory (7), including a user program (11) and a setting document (13), where the user program (11) records both of a command for the communication interface device and command target information thereof, and the setting document (13) saves address information corresponding to the command target information; and a processor (8), reading the user program (11) and the setting document (13) to execute the command.