Unable to echo ros2 topic from drone to a computer

[Aniruddha]

Hello, I was trying to use subscribe to ros2 topics from drone to my computer. I can see the ros2 topics lists from drone on to the computer. But when it try to use ros2 topic echo command from computer I am getting following error.

terminate called after throwing an instance of 'std::bad_alloc'
what(): std::bad_alloc

If I use echo on drone I can see topics printing. but can't do it on computer. can anyone help me with this.

[ApoorvThapliyal]

Hey @Aniruddha,
Thanks for reaching out, could you provide more information about your setup and how things are communicating?

[Aniruddha]

@ApoorvThapliyal, Hi, I set ros domain id on both drone and the pc. they are connected it through the access point. I can ping both drone and pc from one and another and I can even connect drone to qgroundcontrol. That is why I am thinking it might be the ros side issue. I also check for micro dds agent and it was enable and running. I have setup the static ip on drone. I added following command in /etc/dhcpcd.conf file

interface wlan0
static ip_address=192.168.x.xx/24
static routers=192.168.x.xx
static domain_name_servers=8.8.8.8

Let me know if you need anything else you need.

[ApoorvThapliyal]

Hey @Aniruddha
As I understand it, you are able to see the topics on your computer but cant echo them. Which topic are you trying to echo so I can try to recreate it on my end?

[Aniruddha]

@ApoorvThapliyal I was trying to echo /imu_apps

[Aniruddha]

@ApoorvThapliyal I forgot to mention that the error occurred on drone side for voxl_mpa_to_ros2_node. While on computer it is not printing anything

[ApoorvThapliyal]

Hey @Aniruddha
I tried recreating the issue on my setup using a Starling V2 Max connected to my computer over Wi-Fi. On my end, I’m able to echo ROS 2 topics both on the drone and from the computer without any issues. I even added the same static IP configuration you used, and I was still able to echo my topics without any errors.

You also mentioned seeing an error on the drone side for the voxl_mpa_to_ros2_node, could you clarify what the exact error is? Are you unable to run ros2 topic echo directly on the drone as well, or is the problem only when echoing from your computer? Additionally, which drone model are you using?

[Aniruddha]

@ApoorvThapliyal

This is how its being showing

[ApoorvThapliyal]

@Aniruddha
What version SDK are you using? What are the versions of voxl-mpa-to-ros2, voxl-microdds-agent , voxl-ros2-foxy and voxl-px4. You can find it with the command: voxl-version
My suspicion is that the ros2 message being published is of a different size than what ros2 subscriber is expecting, and that's causing the break
Here are the versions I used that worked for me:
voxl-mpa-to-ros2 0.0.7-202511100959
voxl-microdds-agent 3.0.0-0-202511141239
voxl-ros2-foxy 0.0.1-202511141235
voxl-px4 1.14.0-2.0.134

[Aniruddha]

@ApoorvThapliyal sorry for the late reply. my drone got bricked so I had to reinstall everything. I am still facing the same issue.

here are the sdk versions
voxl-sdk is 1.6.3
voxl-mpa-to-ros2 0.0.7
voxl-microdds-agent 3.0.0-0
voxl-ros2-foxy 0.0.1
voxl-px4 1.14.0-2.0.133

also one more thing I forgot to mention before was I was initially was not able to see ros2 topics from drone on my computer but when I install netcat on drone then I was able to see those topics. but I still can't echo them

[ApoorvThapliyal]

@Aniruddha
Even after matching the versions, I am not able to recreate your error
I will try relfashing my voxl2, to start from a clean slate similar to your setup right now.
Since you reflashed the voxl2, is there something you changed on the voxl2 for your goals? I assume that after a reflash, I should have the same setup as you

[Aniruddha]

@ApoorvThapliyal does my ros2 version on my computer could be an issue. I have ros2 jazzy running on my computer where drone has foxy

[ApoorvThapliyal]

Hey @Aniruddha
I was able to recreate your issue with ROS2 jazzy, seems like there is a mismatch between topic size between the versions.
I use humble on my laptop and havent faced any issues, try using it and let me know your results

I'll investigate this issue further

[Aniruddha]

@ApoorvThapliyal Thank you for your help. also I was able to work with jazzy by only subscribing and printing with node. since error only occurred when I tried to echo the topic and not when another node is subscribing it. but using docker seems like most viable option to me since I m using ubuntu 24.04. Thank you for your help again