Dual CAN-FD Bus Redundancy for Deterministic Fail-Over
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is no standard for redundancy on a CANOpen FD network, and existing approaches for CANOpen redundancy reduce deterministic operation and make bumpless fail-over in bus failures problematic.
Innovation Solution
A method for a CAN-FD network with dual busses, where a SYNC message designates one bus as active and another as backup, with frames including sequence numbers, ensuring frames with correct sequence numbers are processed and duplicates are deleted, and implementing fault detection and management to maintain high availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a managed approach to network redundancy is used for CANOpen, then device independence and manufacturer independence are improved, but deterministic operation is reduced and bumpless fail-over becomes problematic
Solution Approach 1:
The system segments the redundant bus configuration into two distinct modes: active-standby mode for deterministic operation and active-active mode for enhanced redundancy. This segmentation allows the system to choose the appropriate mode based on requirements, resolving the contradiction between adaptability and deterministic operation by providing both specialized configurations within a unified protocol framework
Solution Approach 2:
The system dynamically switches between operational modes (active-standby and active-active) and between primary and backup busses based on real-time bus health status and configuration settings. This dynamic behavior enables bumpless fail-over while maintaining deterministic operation characteristics, as the transition mechanisms are predefined and controlled through the CAN-FD protocol
2Reliability
If redundancy is implemented on CANOpen network, then protection against hardware failures is improved, but the deterministic operation and bumpless fail-over capability deteriorate
Solution Approach 1:
The system performs preliminary actions by pre-configuring both primary and backup busses with all necessary communication parameters, device identifiers, and operational modes before any failure occurs. The backup bus remains pre-loaded and ready to activate immediately, eliminating fail-over time delays and enabling bumpless transition while maintaining protection against hardware failures
Solution Approach 2:
The system continuously monitors bus health status through feedback mechanisms including error counters, message acknowledgment verification, and periodic health check messages. This real-time feedback enables automatic detection of bus failures and triggers immediate switch to the backup bus, minimizing fail-over time while ensuring protection against hardware failures through continuous surveillance
3Reliability
If dual CAN-FD busses are used for high availability, then fault detection capability is improved, but system complexity increases
Solution Approach 1:
The system implements universal fault detection mechanisms that operate across both single and dual bus configurations using the same protocol and message structures. The CAN-FD protocol itself provides multi-functionality by handling both data transmission and bus health monitoring through integrated error counters and acknowledgment messages, reducing system complexity while maintaining enhanced fault detection capability through dual bus architecture
Data Source
AI summary
Controller Area Network with Flexible Data Rate (CAN-FD) system and method providing high availability, redundant process control I/O. A server device coupled to dual CAN-FD busses generates a SYNC message designating one of the dual busses as active and another one as backup. The server device transmits the SYNC message on the active bus and then immediately transmits the SYNC message on the backup bus. A client device coupled to the dual busses transmits process data frames on the busses in response to the SYNC message. Each of the process data frames includes a sequence number for the current communication cycle and indicates on which of the dual busses the process data frame is being transmitted.