Hands-On ROS for Robotics Programming

A node that listens to the topic

As there is one node that publishes the incremental counter in the /counter topic, we will now launch a node that subscribes to this topic.

To start, let's visualize the current ROS graph by issuing the following command in T3:

T3 $ rqt_graph

A window pops up and shows this:

There is a single node, that is, the one we launched in T2. The /counter topic does not appear because no other node is listening to it. In order to make the topic show, launch the listener in T4:

T4 $ rosrun ros_basics topic_subscriber.py

You will see this log in the bottom-right terminal window, a neverending live data stream unless you ...