The ROS bridge enables two-way communication between ROS and CARLA. The information from the CARLA server is translated to ROS topics. In the same way, the messages sent between nodes in ROS get translated to commands to be applied in CARLA.
*__ROS Kinetic/Melodic__ — Install the ROS version corresponding to your system. Additional ROS packages may be required, depending on the user needs. [rviz](http://wiki.ros.org/rviz) is highly recommended to visualize ROS data.
*__CARLA 0.9.7 or later__ — Previous versions are not compatible with the ROS bridge. Follow the [quick start installation](start_quickstart.md) or make the build for [Linux](build_linux.md).
*__CARLA release packages__ — Provide support for Python2 and Python3, so these can be used with any ROS version.
*__Windows build__ — Provides Support for the default Python installation in the system, so the ROS installation should match this.
*__Linux build__ — Provides support for Python3 by default (ROS Noetic). If Python2 is needed, the PythonAPI can be built for Python2 running the following command in the CARLA root directory.
To install ROS bridge versions prior to 0.9.10, change to a previous version of the documentation using the pannel in the bottom right corner of the window, and follow the old instructions. 
A catkin workspace is needed to use the ROS bridge. It should be cloned and built in there. The following code creates a new workspace, and clones the repository in there.
The path to CARLA Python is missing. The apt installation does this automatically, but it may be missing for other installations. Execute the following command with the complete path to the <i>.egg</i> file (included). Use the one supported by the Python version installed.
To modify the way CARLA works along with the ROS bridge, edit [`share/carla_ros_bridge/config/settings.yaml`](https://github.com/carla-simulator/ros-bridge/blob/master/carla_ros_bridge/config/settings.yaml).
*__Host/port.__ Network settings to connect to CARLA using a Python client.
*__Synchronous mode.__
*__If false (default).__ Data is published on every `world.on_tick()` and every `sensor.listen()` callbacks.
*__If true__ The bridge waits for all the sensor messages expected before the next tick. This might slow down the overall simulation but ensures reproducible results.
*__Wait for vehicle command.__ In synchronous mode, pauses the tick until a vehicle control is completed.
*__Simulation time-step.__ Simulation time (delta seconds) between simulation steps. __It must be lower than 0.1__. Take a look at the [documentation](adv_synchrony_timestep.md) to learn more about this.
*__Role names for the Ego vehicles.__ Role names to identify ego vehicles. These will be controllable from ROS and thus, relevant topics will be created.
To control the step update when in synchronous mode, use the following topic. The message contains a constant named `command` that allows to __Pause/Play__ the simulation, and execute a __single step__.
The [Control rqt plugin](https://github.com/carla-simulator/ros-bridge/blob/master/rqt_carla_control/README.md) launches a new window with a simple interface. It is used to manage the steps and publish in the corresponding topic. Simply run the following when CARLA in synchronous mode.
