Create3 connects but goes into error mode when command is sent

[rushabhdhoke]

I am working with create3 education [raspberrypi 4b + RPLidar and D435i camera on top] in my lab, for the past few days I was having difficulty connecting it to wifi and getting access to its topics using another pc, found my wifi was blocking subnets.

So today I connected the robot, RPI4 and my pc to mobile hotspot.

Now I can see the topics and nodes of the robot. But now I have another issue that when ever I send any command even something as simple as

ros2 topic echo /<robot_name>/battery_state

sometimes I can get the output of the script, but then immediately the robot's light becomes solid Red and my connection automatically disconnects. After a few seconds, If I do

ros2 daemon stop
ros2 daemon start

The robot turns back on and connects to the wifi and I can see topics again. This is a wierd behaviour, didn't find any other issues similar to this.

Specs:
Create3
-- Version H.2.5
-- Ubuntu 22.04
-- Humble

PC specs:
-- Jazzy
--Ubuntu 24.04

IDK if this is a ros2 inter-compatibility issue, {messages from Jazzy are not able to be understood by Humble}?

[royito55]

This is not an inter-compatibility issue between Jazzy and Humble.

It is an inherent hardware/DDS issue with the Create 3. The multicast DDS data that is sent/received by the Create 3 is too much for its memory, so the PC crashes and the light becomes red.

This is why iRobot added the ROS Discovery server and the ability to add a custom DDS XML file in the web server: to improve DDS communication issues.

Also, starting/stopping the daemon doesn't do anything. It exists purely for introspection, but in a small PC like this one, even starting the daemon considerably increases the memory load, so maybe that's why stopping it felt like something was happening.

Your best bet is to follow either the ROS Discovery server instructions or create a custom DDS XML file that defines how the nodes in the Create 3 communicate.

We actually have a video on this topic, but it's for the TurtleBot 4. You can watch here, it might give you some ideas.