Redundant Supervisory Control System with Circular Loop Networks
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Solution Overview
Problem
Conventional supervisory control systems face issues with temporary interruptions and inaccessibility of remote I/O units due to failures in transmission paths, especially when multiple locations are affected, leading to incomplete data transmission and system disconnection.
Innovation Solution
A redundant supervisory control system with multiple loop interface units and circular loop connections allows for automatic selection of operational units and prioritization of control rights based on connection statuses, enabling continuous operation without switching control rights when failures occur in non-overlapping loop network segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ring connection scheme is used to improve system reliability against single failures, then the controller can access remote I/O units after single failures, but the system becomes inaccessible when failures occur in multiple locations
Solution Approach 1:
The patent divides the ring network into multiple independent segments by introducing a bypass path that creates alternative communication routes. When failures occur in specific segments, the system can segment the network logically to isolate failures and maintain accessibility to remote I/O units through alternative paths, thus resolving the contradiction between reliability and accessibility under multiple failures.
Solution Approach 2:
The patent introduces an intermediary bypass path that acts as a mediator between the controller and remote I/O units. This bypass path provides alternative routing when the primary ring path is blocked by multiple failures, maintaining system accessibility while preserving the reliability benefits of the ring structure.
2Reliability
If a dual supervisory control system is used to provide redundancy, then the system can continue control after breakdowns, but control is temporarily interrupted when switching from active to standby system
Solution Approach 1:
The patent implements preliminary action by pre-configuring multiple loop interface units and establishing their operational status before failures occur. The system proactively monitors and identifies functional units in advance, so when failures occur, the switch to backup units can be performed without temporary control interruption, as the backup units are already prepared and validated.
Solution Approach 2:
The patent employs feedback mechanisms to continuously monitor the operational status of loop interface units and dynamically adjust the active/standby configuration. This real-time feedback enables the system to detect functional units and switch control without interruption, eliminating the time loss associated with traditional active-standby switching.
3Reliability
If automatic switching between active and standby systems is implemented to maintain control, then system continuity is improved, but unnecessary switching occurs when failures are localized and do not affect common transmission paths
Solution Approach 1:
The patent applies local quality by enabling independent operation of multiple loop interface units with different communication paths. Each unit can be evaluated locally for functionality, and the system can maintain control through the functional unit without requiring global switching. This localized evaluation prevents unnecessary switching while maintaining system continuity.
Solution Approach 2:
The patent implements dynamic adaptability by allowing the system to flexibly select among multiple operational configurations based on real-time failure conditions. Rather than rigid active-standby switching, the system dynamically determines the optimal operational mode, preventing unnecessary switching while maintaining continuity and reducing control complexity.
Data Source
AI summary
An object is to provide a redundant supervisory control system and a redundancy switching method thereof. In the redundant supervisory control system, remote I/O apparatuses are less likely to be inaccessible, even in a case where failures occur in plural locations. Thus, the reliability of the system is enhanced. The redundant supervisory control system including a plurality of first loop interface units in each of a pair of controllers, second loop interface units, and communication cables each connecting the plurality of first and second loop interface units with one another in a circular loop. The redundant supervisory control system is configured by connecting the controllers and the remote I/O units to one another in a plurality of loop networks. In a case where abnormality in the loop networks is detected by use of received data in the networks, the first and second loop interface units that can perform normal reception are automatically selected.