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00
Guided beta caseProbeginnerPublisher control flow

The topic exists but publishes nothing

Restore odometry output without changing the message type or topic name.

Pairs with Topics and message flow in ROS 2 Systems Debugging. Read the concept first, then diagnose it here.

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Operator report

`/wheel/odometry` has a publisher, but `ros2 topic hz` receives no samples.

Ubuntu 24.04, ROS 2 Jazzy, Python and C++ nodes, browser telemetry workspace

01

System boundary

Trace only the relevant path.

3 nodes
  1. 01encoder timer→
  2. 02odometry publisher→
  3. 03/wheel/odometryOUT
02

How this lab works

You diagnose it. No command list.

Open the repair workspace and gather your own evidence in a real terminal. No diagnostic commands are handed to you - finding the fault is the exercise. Stuck? Progressive hints unlock inside the workspace.

03

Verification

Pass more than the visible symptom.

4 checks
  • Odometry rate exceeds 25 Hz
  • Timestamps increase monotonically
  • Hidden regression behavior
  • Root cause explanation