Questions about Blank messages of ROS2 Toolbox

Hello!

I have a problem with the ROS2 Toolbox.

I want to change the blocks from ROS1 to ROS2, but when I try to set the message type to geometry_msgs/poseArray, it will automatically change to another types, which means I can't select this type of message.

Do you know why and how can I solve it？

Thanks!

Answer 1

[Abhijeet Gadkari]

Hello Xiaochen,

Information about variable sizes of a ROS message is stored in the model workspace, when you save a Simulink model with a ROS block that has a message type that has fields with variable sizes. You can change the maximum length of variable-size messages using the VariableSize Messages app in SIMULATION > PREPARE tab under ROS TOOLBOX section.

Adding a ROS 2 block to a Simulink model previously saved with ROS blocks, corrupts this information and causes problems when selecting ROS 2 block message type parameter.

Possible solutions are as follows:

1. Create a new model by copying non-ROS blocks and add the ROS 2 blocks
2. To avoid creating a new model, delete the ROS variable size data from the model and save the model. Use the following MATLAB commands and save the model:

modelWs = get_param(<modelName>, 'ModelWorkspace');
evalin(modelWs, 'clear SL_ROS_VariableLengthArrays_MaxSizes');
save_system(<modelName>);

- Abhijeet