Heartbeat

Heartbeat is the at-a-glance liveness check for the dashboard: it shows ALIVE, STALE, or NO SIGNAL from whether messages are still arriving on Topic, with no message-type field and no payload check, so it works against any topic. For a fuller connection summary (status, latency, topic count, bandwidth), Robot Status (Pro) is the richer widget.

Point Topic at /odom (nav_msgs/msg/Odometry), which a mobile base publishes continuously while running. Leave Timeout (ms) at the shipped default of 3000: elapsed time under that reads ALIVE, up to 3x Timeout (9 seconds here) fades to STALE in amber, and beyond that flips to NO SIGNAL in red. Size Timeout (ms)around your topic's normal publish interval, not a guess, since that 3x window is the only grace period before it reads fully dead.

• A topic that only fires once, like a latched static transform, reads ALIVE for one Timeout (ms) window, then fades through STALE to NO SIGNAL exactly like a dead topic. Pick a continuously-publishing topic, not a one-shot.
• Heartbeat reads alive from any message arriving, never the content. A node publishing malformed data still shows ALIVE, so this is a link check, not a data-quality check.