Graph card

The Graph card plots one or more device metrics over time. It is the card most dashboards are built from, and the one that follows the dashboard's time range.

Use it when

• You need to see how a measurement changes over time.
• You want to compare related measurements on the same axis.
• You want a card that moves with the dashboard time range.

Configure it

Select the device, then the metric, for each series you want to plot. That order is the same everywhere in BDI Cloud — Connections, devices, and metrics explains why.

Values produced by a Virtual Device can be plotted here too, alongside raw device metrics.

The card takes its window from the dashboard rather than carrying its own. Changing the dashboard time range changes every Graph card on the page at once.

Two Y axes

A Graph card has a left axis and an optional right one. Each carries its own devices, metric, unit and label, which is what lets you plot two quantities that share a time base but nothing else.

This is the answer to plotting a crackmeter against temperature. On one axis the temperature swamps the displacement and the displacement looks flat; on two, both are readable and any correlation between them becomes visible.

Use it when the two measurements are related and you want to see them together. Don't use it to squeeze unrelated series onto one card — a reader has to check which axis each series belongs to, and that cost is only worth paying when the comparison is the point.

Set the unit per axis rather than accepting the default when a metric can arrive in more than one. Decimal precision is also per card, and worth reducing when values are noisy.

Reading it

Hovering a point shows its value with the unit, which is the quickest way to confirm a series is in the units you assumed.

The legend can be hidden entirely or sorted A–Z from card settings, and individual series hidden or isolated by clicking them. On a card carrying more than a handful of series, isolating one is usually faster than rebuilding the card to look at it alone.

Getting a readable chart

Plot things that share a unit and a sensible range on the same axis. A measurement in millimetres and one in degrees on one axis will leave the smaller as a flat line. Either use the second axis or use separate cards.

Watch the number of series. A card with dozens of series is a colour-matching exercise, not a chart. Split by instrument group or location instead.

Check the unit before drawing conclusions. A vendor export may deliver raw counts or frequencies rather than engineering values, so a series that looks wrong in magnitude is often correct data in an unexpected unit.

A flat line is ambiguous

A flat trace can mean a stable site, or it can mean the readings stopped arriving and you are looking at nothing. The chart looks the same either way.

This is why a Device health card belongs on any dashboard people rely on, and why stale data alerts exist.