How to implement multi device data recording setup?

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Thank you very much.

I assume it is worth to test it with WiFi and see how well it works. One Pi would collect LiDAR data (2D) at 20 Hz and the other Pi's would collect IMU data at 120 Hz. Do you think this could already be too much for the bandwidth?

Thanks for the link, I will try to understand as much as I can. Do you know which hardware solution they used for the wireless connection?

I would also need to ensure that data is recorded in bag files preferably on both the master and the client, so that in case connection interrupts, the recording is not interrupted.

I have no idea for the bandwidth. But generally, ROS 1 over Wifi is not the best idea. I am not sure how well the disconnections are handled by the master. Another solution would be to run one master per Pi (like in the video), and communication between the Pis managed differently. We have used rosserial over TCP to do such use case.

Thanks for the quick reply. Maybe then it is better to record on the clients directly instead of streaming everything to the master, for safety reasons. Sending commands to start/stop recording from the master should be no issue via rosbridge I suppose. You mention ROS 1, would you say I should look into ROS 2 for this setup? I have no experience yet with ROS 2.

Another follow up question on your initial answer: If I can see the topics sent by the clients, will I also see which client is publishing them? And can I send messages via service to certain clients?

In theory, ROS 2 handle Quality of Service to deal with bad connections. But I have not personally tried it. Yes, you can communicate in both directions with the clients.