Clone the repo to your colcon_ws

cd colcon_ws/src
git clone https://github.com/dasc-lab/ros2-ping

Build the workspace

cd colcon_ws
colcon build

Source the workspace

source install/setup.bash

One one terminal, start pong node

ros2 run ping pong

This node waits for messages on the /ping topic. When it receives something, it will republish the same message to the /pong topic.

On the other terminal, start the ping node

ros2 run ping ping

This node sends out a message on the ping topic every 500ms. Whenever it receives a message on the pong topic, it alculates the time difference. It prints the time difference to console, and also publishes it to the /round_trip topic as a builtin_interfaces::msg::Duration msg.

One a single computer, the ping should be about 1 ms.