Redundant Control Node Architecture for Real-Time I/O Punctuality
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Solution Overview
Problem
Control systems in factory and process automation face challenges in maintaining punctuality and reliability, especially when upgrading or replacing resources, as they require high availability and cannot be frequently stopped, and existing techniques do not provide methods for changing programs or computers while maintaining high punctuality.
Innovation Solution
A control system architecture with a control node running a general-purpose OS and an I/O node running a real-time OS, allowing for synchronized operation and resource changes without stopping the system, using a determination execution unit to generate control commands and an I/O program to execute them with high punctuality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a real-time OS is used to ensure high punctuality in control systems, then control timing precision is improved, but program complexity and adaptability deteriorate because programs developed for general-purpose OS cannot be easily executed on real-time OS
Solution Approach 1:
The system is divided into two independent parts: a control program developed on general-purpose OS and an I/O program executed on real-time OS. These segments communicate through well-defined interfaces (transmission data structures), allowing each to operate in its optimal environment without compromising the other.
Solution Approach 2:
Transmission data structures serve as intermediaries between the control program (on general-purpose OS) and the I/O program (on real-time OS). These data structures enable data exchange and coordination while maintaining the independence and compatibility benefits of both environments.
2Reliability
If the control system is configured with redundancy to maintain continuous operation, then system availability is improved, but program synchronization complexity and difficulty of operation worsen
Solution Approach 1:
When a control program is updated, the updated version is copied to both the current control node and the standby control node. This ensures both nodes have identical program versions, simplifying synchronization in redundant configurations.
Solution Approach 2:
The system monitors the operational status of control nodes and automatically switches to standby nodes when failures are detected. This feedback mechanism maintains system availability while reducing the operational burden of managing redundancy.
3Reliability
If the control system is stopped to replace software or hardware, then resource reliability is improved, but productivity and loss of time worsen due to frequent stoppages
Solution Approach 1:
Standby control nodes are prepared in advance with identical or updated program versions. When a control node needs maintenance or replacement, the system can immediately switch to the pre-prepared standby node, avoiding stoppages and maintaining productivity.
Solution Approach 2:
The system dynamically switches between control nodes based on operational status. This dynamic allocation allows maintenance and replacements to occur without interrupting control functions, as the system adapts by activating standby resources.
Data Source
AI summary
In a control system including one or more control nodes and one or more I/O nodes connected to one or more devices and communicable with the control nodes, the control nodes execute at least one control program on a first OS, and the I/O nodes execute at least one I/O program on a second OS with higher punctuality. The control program generates a control command based on state control set in advance for the device and transmits the control command to the I/O node. The I/O program stores the control command received from the control node in a storage unit, and executes processing related to the device according to the control command stored in the storage unit.