Hi Vex Forums,

First time poster solo apologies if any rules are broken. Please advise if they are.

I’m using the Rosserial package for the Vex V5 Brain, but experiencing issues making the brain receive any messages more complicated than basic strings (callback functions in C++ code on the brain are not executed, leading me to believe data is being sent but not properly received).

Has anyone else used this package before and would be willing to talk to me about solving some of these issues/allowing the brain to receive other messages, such as geometry_msgs/Twist?

Thank you!

I have some experience with rosserial on the brain, and have experienced similar issues to what you are saying. What helped fix it for me is to go into /include/ros_lib/V5Hardware.h, and find ROSVEX_BUFFER_INPUT_SIZE, which I believe was set to 32 bytes by default. I changed it to 512 and was then able to recieve joy messages. I suggest that you join the VEX Discord ( as several members there have significantly more experience with rosserial than I do and may be able to help you if this doesn’t.


That’s awesome, thank you very much! Looking forward to joining the discord!


FYI for anyone else viewing this thread: sazrock’s fix was what was wrong, he’s a real MVP!