Value Display
FREENumeric or text value from any topic
When to reach for it
Value Display reads one field from a topic by dot path and shows it as a number or a line of text: the generic fallback when nothing else fits. For a trend, use Sparkline or Time Series (both Pro).
For battery percentage, Battery Gauge handles the fill and color bands; for a full pose, Pose Display (Pro) reads all six numbers at once.
Worked example: battery voltage on a TurtleBot 4
TurtleBot 4's Create 3 base publishes sensor_msgs/msg/BatteryState on /battery_state. Set Topic there, Field Path voltage, Format Number, Unit V, Decimal Places 2. On Pro, set Alert Direction to Warn when below and set Warning and Critical Threshold to whatever voltage matters for your pack.
Watch out for
- Field Pathpointed at a struct doesn't show the struct. Number mode fails its type check and falls back to
--; Text mode stringifies the object and renders the literal[object Object]. Point it at a leaf value instead. - Warning Threshold and Critical Threshold both default to 0, and color coding only activates once one of them is nonzero: leave both alone and Alert Direction silently does nothing.
- The subscription is capped at 10 Hz regardless of the topic's real publish rate, dropped before parsing. A fast IMU field will step visibly, not glide.
Configuration fields
The topic this widget reads data from. While connected, tap to pick from the topics the robot advertises.
Which field inside the message to read, as a dot-path, e.g. pose.position.x. Leave blank to use the message main value.
Which side of the threshold triggers a color change.
WITH PRODrives the Warning/Critical thresholds below. "Warn when above" is right for temperature, current, error counters; "Warn when below" is right for battery, signal strength, fluid levels.
Value at which the display turns amber.
WITH PROCombined with Alert Direction, this is the first warning band. Text shifts to the theme's warning color so you notice it without reading the number. Critical Threshold is the harder line below.
Value at which the display turns red.
WITH PROHard alarm band. Text turns red and the widget border pulses subtly. Use for thresholds where the operator should stop and check the robot, like battery below 10%, current draw past safe limits, or error counters incrementing.
Show the running minimum and maximum since the widget connected.
WITH PROTiny "min / max" pair under the live value. Useful for one-off measurement runs (peak current, max temperature on a long run, deepest dive) without wiring up a full plot. Resets when the widget reconnects.
Text prepended to the value.
WITH PROFor things like "Pkg #" before an integer, or "→ " before a string. Pairs with Suffix for full custom labelling without wrapping the widget in another component.
Text appended to the value.
WITH PROCommon uses: units the widget doesn't already know (" kg", " rpm"), state markers (" OK"), or symbols (" ∘C"). Independent of the Unit field, which is locked to a fixed list.
Show a name on the widget.