CAN-Open Redundancy Switching in PLC Wellsite Control
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Solution Overview
Problem
Existing PLC-based control systems for wellsite operations face challenges in ensuring continuous communication and control due to limitations in CAN-open protocol features, particularly in configurations where redundancy is necessary but not fully supported.
Innovation Solution
The implementation of a system that includes multiple programmable logic controllers (PLCs) and CAN modules, with a fail-over logic mechanism that allows seamless switching between primary and backup PLCs and CAN modules, ensuring continuous operation even in case of failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single CAN module is used in the PLC-based control system, then the device complexity is reduced, but the reliability is insufficient due to lack of redundancy
Solution Approach 1:
The system pre-configures multiple CAN modules (primary and backup) and establishes fail-over logic before any failure occurs. The backup CAN module and associated PLC are ready in advance to take over communication functions if the primary CAN module fails, ensuring continuous operation without interruption.
Solution Approach 2:
The patent implements redundant CAN modules and fail-over mechanisms as a protective measure against potential CAN module failures. This cushioning approach ensures that if the primary CAN module fails, the backup module can immediately take over, preventing system downtime and maintaining reliability.
2Reliability
If CAN-open protocol features are fully utilized for redundancy, then the reliability is improved, but the ease of operation deteriorates due to configuration limitations
Solution Approach 1:
The patent introduces an intermediary layer (custom fail-over logic and communication protocols) between the PLC and CAN modules to enable redundancy functionality that goes beyond standard CAN-open protocol capabilities. This intermediary mechanism allows seamless fail-over without requiring complex CAN-open configuration.
3Reliability
If multiple PLCs and CAN modules are implemented with fail-over logic, then the reliability is enhanced, but the device complexity increases
Solution Approach 1:
The system pre-configures multiple PLCs and CAN modules with established fail-over logic before deployment. The backup components and switching mechanisms are prepared in advance, allowing automatic takeover without complex real-time decision-making when failures occur.
Data Source
AI summary
A system for controlling equipment at a wellsite includes a surface PLC, a first subsea PLC, a second subsea PLC, a first CAN module, a second CAN module, and a CAN network. The surface PLC is configured to receive a parameter that is measured by a sensor and to transmit a first signal to the first subsea PLC, the second subsea PLC, or both in response to the parameter. The first subsea PLC or the second subsea PLC, or both are configured to transmit a second signal to the first CAN module, the second CAN module, or both in response to the first signal. The first CAN module, the second CAN module, or both are configured to transmit a third signal to the CAN network in response to the second signal. The CAN network is configured to control the equipment in response to the third signal.