EtherNet/IP Device Level Ring fault isolation
Diagnose a degraded or faulted DLR network by proving supervisor identity, ring topology, port roles, last active nodes, fault location, speed, multicast load, gateway state, and physical media.
- Product
- EtherNet/IP Device Level Ring networks
- Level
- Advanced
- Read time
- 15 min
- Reviewed
- 2026-08-13
- Author
- Toolbox editorial team
- Reviewer
- Technical review
What to establish before troubleshooting
A DLR can continue passing traffic after one break, so healthy controller I/O does not prove the ring is normal or redundant.
Capture active supervisor, ring status, topology, last active nodes, fault count, gateway state, port counters, and physical order before opening the ring or power-cycling participants.
Abbreviated worked example
Example: machine runs with DLR in ring fault
All devices remain connected, but the supervisor reports a ring fault and the system has lost single-fault tolerance.
- 1Record supervisor diagnostics and the reported last active nodes on both sides of the break.
- 2Inspect only the bounded cable and two adjacent ports before changing supervisor or topology settings.
Result: The redundant path is restored without creating a second break or masking the original fault.
Caution: A second fault on a degraded ring can isolate multiple devices; use an approved maintenance window and preserve the physical order.
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