Explore historical trends

Why history matters

Controller values describe the current machine state, but PLC logs are often too short for later production analysis. PlantWatch stores configured states and process values so teams can review them after an event.

Historical context helps distinguish a brief anomaly from a recurring pattern.

Choose a focused time window

Start with the period surrounding the event you want to understand. Include enough time before the event to see whether a value was already changing.

Expand the window when you need to compare a shift, day, or reporting period. A narrow window reveals event order; a wider window reveals recurrence and drift.

Compare related signals

Look at signals that describe the same part of the process, such as an operating state together with load, temperature, alarm, or interlock values.

Changes that occur close together can provide useful context, but timing alone does not prove causation. Confirm interpretations with process and automation knowledge.

Compare periods consistently

When comparing shifts or dates, use equivalent production conditions where possible. Product changes, planned maintenance, and different operating modes can otherwise make two periods look more different than they are.

Record the question and selected period so another team member can repeat the comparison.

Turn trends into recurring information

When a comparison is needed regularly, summarize it through Automated reports. For a specific production stop, return to Analyze downtime.