EVIDENCE GUIDE

What to record during a Modbus commissioning session

Record the layer that can answer the next person’s question. A trend explains how decoded values changed. Raw traffic explains which protocol exchange created the value or failure. In difficult cases you may need both, aligned around one short reproduction.

01

Use Trends for process behavior

Attach only the signals relevant to the event and confirm every source is running. Capture a stable period before the action, the action itself, and recovery. Keep units and decoding definitions with the project so exported numbers remain interpretable.

02

Use Raw Traffic for protocol behavior

Record when investigating exceptions, retries, latency, unexpected function codes, or malformed responses. Filter after the capture rather than discarding surrounding frames too early; the request immediately before the failure is often relevant.

03

Keep a small reproducible package

Save the project after reviewing private endpoints and certificate paths. Add the native session and a short note describing expected versus actual behavior. Export CSV or a report for convenience, but keep the original session as the inspectable evidence.

KEEP THE EVIDENCE

Use the manual beside the live protocol.

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