01
Start with the medium
Inspect cabling, shielding, connectors, power and switch-port status before changing protocol settings. Physical errors and intermittent links can appear as higher-level communication faults.
02
Map the topology and timing
Document devices, address plans, paths and communication roles. Compare expected update intervals, timeout settings and network load with the requirements of control and diagnostic traffic.
03
Use protocol evidence
Check device diagnostics, counters, packet captures and controller logs together. Confirm identity, data mapping, quality indicators and recovery behavior after a link interruption.