EtherCAT Cable Redundancy for Stable Distributed Clock Synchronization
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Solution Overview
Problem
EtherCAT systems face challenges in maintaining both cable redundancy and distributed clock synchronization when disconnections occur, leading to synchronization issues among slave devices.
Innovation Solution
A method and master device that support cable redundancy and distributed clock synchronization by establishing network topology information, disabling redundant connections temporarily, performing synchronization procedures, and enabling connections as needed to maintain synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cable redundancy is implemented in EtherCAT systems, then system reliability is improved, but distributed clock synchronization accuracy deteriorates when disconnections occur
Solution Approach 1:
The system dynamically adjusts the network topology by temporarily disabling redundant connections during disconnection events, transforming the static redundant topology into a dynamic configuration that maintains synchronization accuracy. The master device controls the switching between redundant and non-redundant modes based on real-time network status, allowing the system to adapt its structure to preserve clock synchronization precision.
2Measurement precision
If redundant connections are disabled temporarily to maintain synchronization, then synchronization accuracy is improved, but system availability deteriorates
Solution Approach 1:
The system performs preliminary configuration of redundant connections in normal operation, preparing the network topology in advance for potential disconnection events. When disconnections occur, the pre-configured redundant paths can be quickly activated or adjusted without requiring complex real-time reconfiguration, thus maintaining both synchronization accuracy and system availability.
Solution Approach 2:
The system changes the operational parameters of redundant connections by adjusting their enable/disable states based on network conditions. By dynamically modifying the connection parameters (enabled/disabled) rather than the physical topology, the system maintains synchronization accuracy while preserving availability through parameter adjustment rather than structural change.
3Measurement precision
If distributed clock synchronization procedure is performed after reconnection, then synchronization accuracy is improved, but time consumption increases
Solution Approach 1:
The system performs preliminary clock synchronization configuration during normal operation before disconnections occur. This preliminary setup includes pre-calculating time delay parameters and establishing reference clock relationships, so that when disconnections and reconnections happen, the synchronization can be quickly restored using the pre-prepared configuration data without requiring a complete resynchronization procedure.
Data Source
AI summary
In the initial phase, the master device is configured to disable the connection between the junction device and the last slave device before performing the EtherCAT distributed clock synchronization procedure. After completion, the connection between the junction device and the last slave device is enabled. When a disconnection occurs in a closed loop topology, the junction device can serve to provide a redundant path for forwarding datagrams, thereby achieving cable redundancy. After the disconnection is fixed, the system time delay of each slave device calculated during the initial phase can still be applied without needing to perform again the distributed clock synchronization procedure.