Question 1

How to create a custom ROS 2 message using rosidl?

Accepted Answer

Define a .msg file in your package's msg directory with the message structure, then use rosidl_generate_interfaces() from rosidl_cmake in CMakeLists.txt to automatically parse and generate C/C++ code during the build process. Ensure your package depends on rosidl_cmake and related packages.

Question 2

What's the difference between rosidl and ROS 1's genmsg?

Accepted Answer

rosidl is the ROS 2 successor to ROS 1's genmsg, introducing a modular, language-agnostic approach based on .idl files instead of direct code generation. It supports additional interface types like actions and integrates better with modern build systems like CMake for improved scalability.

Question 3

Can I use rosidl without installing full ROS 2?

Accepted Answer

No, rosidl is tightly coupled with the ROS 2 ecosystem and requires ROS 2's build tools, dependencies, and workspace setup. It's designed to work within a colcon build environment and isn't a standalone IDL tool for generic use.

Question 4

How to generate Python code for ROS interfaces with rosidl?

Accepted Answer

rosidl itself focuses on C/C++ generation; for Python, you need additional packages like rosidl_generator_py. In a ROS 2 package, Python bindings are typically generated automatically when built with colcon, assuming the package declares the correct dependencies and follows ROS 2 conventions.

Question 5

rosidl vs Protobuf for robotics applications – which is better?

Accepted Answer

For ROS 2-native projects, rosidl is the standard and ensures seamless integration with ROS 2 middleware and tools. Protobuf is more general-purpose and portable but requires additional layers to interface with ROS 2, so choose rosidl for ecosystem consistency and Protobuf for cross-platform systems outside ROS.

Question 6

Troubleshooting common CMake errors with rosidl code generation

Accepted Answer

Common errors include missing file paths or incorrect dependencies. Check that .msg files are in the correct directories (msg/, srv/, action/) and that rosidl_cmake is properly included in CMakeLists.txt. Refer to ROS 2 documentation for specific error codes and ensure your package meta files are up to date.

rosidl_generator_cpp

What is rosidl_generator_cpp?

Overview

Use Cases

Best For

Related Projects

Found a gem we're missing?

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions