PLC Data Publishing Control for Secure External Access
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Solution Overview
Problem
Existing programmable logic controllers (PLCs) face challenges in managing data exchange with external devices, as the data requirements vary depending on situations, and there is a need for improved security and precise control over process values and their accessibility.
Innovation Solution
A programmable logic controller (PLC) system that dynamically manages data exchange based on the execution result and operating state of the control program, allowing specific settings for process value accessibility and changeability, with enhanced security features to prevent unauthorized access, using a communication protocol like OPC-UA for interoperability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If data exchange with external devices is allowed freely, then ease of operation is improved, but security is worsened
Solution Approach 1:
The patent implements dynamic publishing settings that automatically adjust data accessibility based on the PLC's operating state. Process values are published or unpublished depending on whether the PLC is in operation, program change mode, or other states, resolving the contradiction between ease of operation and security by making the system adaptive rather than static
Solution Approach 2:
The system changes the publishing parameter of process values based on operating states. When the PLC is in a safe state (e.g., program change mode), data is unpublished; when in operation, data is published. This parameter change approach allows the system to maintain security while enabling operation as needed
2Ease of operation
If all process values are published for external access, then ease of operation is improved, but device complexity is worsened
Solution Approach 1:
The PLC automatically manages its own data publishing based on its operating state without requiring external intervention. The system self-determines which process values should be published based on predefined rules tied to operating states, reducing the complexity burden on operators while maintaining ease of data access when appropriate
3Reliability
If data exchange is restricted for security, then reliability is improved, but ease of operation is worsened
Solution Approach 1:
The system dynamically adjusts security restrictions based on operating states rather than maintaining constant restrictions. Data accessibility is enabled when the PLC is in safe states and restricted when in vulnerable states, resolving the contradiction by making security adaptive to operational context
Solution Approach 2:
The publishing parameter of process values is changed according to operating states. The system transitions between published and unpublished states based on whether the PLC is operating or in program change mode, allowing security to be adjusted without permanent operational restrictions
Data Source
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AI summary
An object is to provide a function of managing data exchanged with an external device. A control device (100) defines a publishing setting (126) of a process value (124) in accordance with information on at least one of an execution result of a control program (122) and an operating state of the control device (100). The control device (100) exchanges a data set (128) including at least part of one or more process values with the external device in accordance with the defined publishing setting (126).