Redundant Field Bus Modules via Ethernet Switches
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Solution Overview
Problem
Existing fault-tolerant methods for process control systems incur undue computational and hardware overhead due to the need for duplicate data streams and complex protocols, leading to slow response times and increased complexity.
Innovation Solution
A system where two field bus modules (FBMs) are communicably coupled through Ethernet switches, with one FBM acting as a master and the other as a tracker, sharing a floating IP address, allowing data synchronization and role switching to ensure redundancy without duplicate data streams, thereby reducing bandwidth and processing overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant field bus modules communicate directly with each other through dedicated communication links, then data synchronization and fault tolerance are improved, but device complexity and bandwidth consumption increase
Solution Approach 1:
The patent merges the communication paths by having both master and tracker FBMs communicate through a common Ethernet switch infrastructure rather than dedicated direct links. This consolidation reduces overall system complexity while maintaining redundancy capabilities through shared network resources.
Solution Approach 2:
The Ethernet switches serve multiple functions: they handle communication between master FBM and tracker FBM, connect to the distributed control system, and provide network infrastructure for the entire FBM pair. This multi-functionality reduces the need for specialized communication hardware and simplifies the overall architecture.
2Reliability
If duplicate data streams are used for redundant FBMs, then data integrity is improved, but bandwidth consumption and processing overhead increase
Solution Approach 1:
Instead of maintaining complete duplicate data streams, the patent uses a master-tracker model where the tracker FBM receives and processes copies of critical data from the master FBM through the Ethernet network. This selective copying approach maintains data integrity for redundancy while significantly reducing overall bandwidth consumption compared to full duplication.
3Reliability
If complex synchronization protocols are implemented between redundant FBMs, then data consistency is improved, but response time deteriorates
Solution Approach 1:
The master and tracker FBMs perform preliminary synchronization actions during normal operation, with the tracker continuously receiving and validating data from the master through the Ethernet network. This preliminary synchronization ensures that when a failover is needed, the transition is rapid because the tracker is already prepared and synchronized, eliminating the need for complex real-time synchronization protocols during critical response moments.
Data Source
AI summary
A system and method for interfacing redundant devices to a distributed control system, includes a first and second redundant field bus modules communicably coupled to the distributed control system and to one another via switches. A pair of redundant field devices are coupled to the switches, one FD having an address. The FBMs adopt respective roles as master FBM and tracker FBM, so that the master FBM is configured to capture data from the one FD using the address, and to pass any data changes periodically to the tracker FBM, through the switches. The master FBM is configured to point to the other field device in the event the other field device has assumed the address. The FBMs are configured to switch roles in the event communication is disrupted between the master FBM and the FD having the address.