Simulink fails to create ROS subscriber

Hi,

I am trying to subscribe to a topic using the subscriber block in Simulink and I am getting the error shown in the attached image. I created the custom message and it appears in the command window when I do rosmsg list, so I don't know why it says it can't find that message in the library. Maybe there is something else I need to add so Matlab finds the generated message. I am using Matlab 2020b.

Thanks

Answer 1

[Cam Salzberger]

Hello Johan,

This may be because you have conflicting libraries on your platform's library path. It may be related to this bug, or this one, that were both fixed in R2020b Update 3. Try getting the latest update and see if that resolves the issue.

Also see here for a similar issue with suggested resolutions. Though that question is regarding ROS 2, similar issues may be found in ROS 1.

-Cam

[Johan Fanas]

I updated my Matlab and it fixed the problem, thanks a lot. I am encountering another problem when running the subscriber and using the ROS bag block (see image attached). I don't know if this might be an issue with my custom message (which I dont think so), but any suggestion would be great. Below is the output when I do rosmessage show from the command window. Everything is correct but I keep getting this error in Simulink. When I use the rosbag block I get the same error but with the timestamp.

msgInfo = rosmsg('show','obstd_radar/ObjectInfoList')

msgInfo =

'std_msgs/Header Header

uint32 VectorLen

ObjectInfo[] ObjectList'

[Cam Salzberger]

Hey Johan,

That issue is a little more difficult to diagnose from the error message. I'd suggest that you contact technical support with your custom message package(s) and your model. They can better dig into what's going on in the model, and diagnose the issue.

-Cam