Virtualized Controller Role Switching Over OT Lines
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Solution Overview
Problem
In distributed control systems, failures in connection cables or communication links can lead to unstable control signals and conflicts between active and standby devices, making it difficult to maintain stable control, especially when using general-purpose networks like Ethernet.
Innovation Solution
Implementing an OT network communication line for transmitting control signals and existence confirmation signals between controller virtualization devices, allowing them to switch roles based on signal reliability, thereby preventing conflicts and ensuring stable control even in failure scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If general-purpose networks like Ethernet are used for transmitting existence confirmation signals between controller virtualization devices, then device complexity is reduced and ease of manufacture is improved, but reliability deteriorates due to cable failures and link breaks causing control signal conflicts
Solution Approach 1:
A dedicated communication line acts as an intermediary channel specifically for transmitting existence confirmation signals between controller virtualization devices. This separate communication path prevents interference from general-purpose network failures, ensuring reliable heartbeat signal transmission while maintaining the use of standard Ethernet for other purposes.
Solution Approach 2:
The communication infrastructure is segmented into separate channels: one for control signals and existence confirmation signals via dedicated communication lines, and another for general data traffic via Ethernet. This segmentation isolates critical control communications from potential network failures, improving reliability without adding complex hardware systems.
2Reliability
If redundant configuration with active and standby devices is implemented, then availability is improved, but device complexity increases due to the need for switching circuits and role management
Solution Approach 1:
Controller virtualization devices transmit existence confirmation signals to each other to provide feedback on their operational status. Based on receiving or not receiving these signals, devices automatically determine their role as active or standby, enabling intelligent role management without complex external switching circuits.
Solution Approach 2:
The controller virtualization devices themselves manage their own role switching based on mutual existence confirmation signals. Each device independently determines whether it should be active or standby by monitoring the absence or presence of signals from its peer, eliminating the need for external switching circuitry and reducing overall system complexity.
3Reliability
If dedicated communication lines are used for existence confirmation signals, then reliability is improved by preventing control signal conflicts, but ease of manufacture deteriorates due to additional cabling requirements
Solution Approach 1:
The dedicated communication line serves multiple functions: transmitting existence confirmation signals, maintaining synchronization between devices, and providing a reliable control channel. This multi-functionality justifies the additional cabling by consolidating several critical functions into a single dedicated infrastructure.
Data Source
AI summary
A controller virtualization device includes: a plurality of controller virtualization devices each configured to generate a control signal for a control object and including at least one virtual machine; and at least one OT line for transmitting the control signal from each of the plurality of controller virtualization devices to the control object. The plurality of controller virtualization devices are configured to mutually transmit and receive an existence confirmation signal or a reliability confirmation signal of the virtual machine via the at least one OT line.