41 lines
1.8 KiB
Markdown
41 lines
1.8 KiB
Markdown
Use this ROS2 package to create custom interfaces, eg. topic (*.msg) and/or service (*.srv) files.
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This package must only be used for interface files and __no__ Python scripts.
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The following steps describe how to create a new custom topic or service.
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## 1. Create new interface file
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Topic *.msg files got into `msg` directory,
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Service *.srv files got into `srv` directory.
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Create these files according to the example on this [instructions page](https://docs.ros.org/en/foxy/Tutorials/Writing-A-Simple-Py-Service-And-Client.html).
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## 2. CMakeLists.txt
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Edit the `CMakeLists.txt` file by adding the newly created *.msg or *.srv files to this part:
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```cmake
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rosidl_generate_interfaces(${PROJECT_NAME}
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"msg/CustomMsg1.msg"
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"msg/CustomMsg2.msg"
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"srv/CustomSrv1.srv"
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DEPENDENCIES builtin_interfaces
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)
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```
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## 3. Build colcon workspace
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Move back to the root of your _colcon_ workspace and rebuild it: `colcon build --symlink-install`
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It should build without any errors. If you encounter errors fix these before continuing.
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After a successful build you must __close and reopen all terminals__ in order to source the newly built workspace. For this to happen you must have edited _.bashrc_ and added your current workspace (`sudo nano ~/.bashrc` and follow [this example](https://egit.irs.uni-stuttgart.de/RoverLehre/ROS2_pubsub/src/branch/master/non-ros-files/bashrc_overlay.bash)).
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## 4. Import interfaces
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Import the newly created interfaces into the Python scripts. These scripts must be located in _Python packages_ inside the same workspace (or another _sourced_ workspace):
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* Topics:
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```python
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from custom_interfaces.msg import CustomMsg1
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```
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* Services:
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```python
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from custom_interfaces.srv import CustomSrv1
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```
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Now you can work with your custom interface in order to exchange custom information between nodes.
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