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Parameters are per node in ROS 2. There is no a global parameter server like ROS 1. It is possible to set a param on a node with ros2 param set
$ ros2 run demo_nodes_cpp parameter_blackboard &
...
$ ros2 param set /parameter_blackboard foo bar
Set parameter successful
$ ros2 param list /parameter_blackboard
foo
use_sim_time
If you'd like to set a parameter on all running nodes, you'll need to enumerate them and set the parameter on each one. If you would like to set a parameter on a lot of nodes that you're launching, the parameter should be passed into each launch_ros.actions.Node.
import launch
import launch_ros
def generate_launch_description():
use_sim_time = launch.substitutions.LaunchConfiguration('use_sim_time', default=False)
return launch.LaunchDescription(
[
launch_ros.actions.Node(
package='demo_nodes_cpp', node_executable='talker',
node_name='talker',
parameters=[{'use_sim_time': use_sim_time}]),
launch_ros.actions.Node(
package='demo_nodes_cpp', node_executable='listener',
node_name='listener',
parameters=[{'use_sim_time': use_sim_time}]),
])
I used a LaunchConfiguration in this example. You can give it a value on the command line
$ ros2 launch example_launch.py use_sim_time:=True
...
$ ros2 param get /listener use_sim_time
Boolean value is: True
It doesn't seem to be possible at the moment. But it is listed on the feature list for the next ROS 2 distribution: https://github.com/ros2/ros2/issues/734
passing key-value parameters on CLI
Can I use the same node for another rclcpp::SyncParametersclient?
I have a node named foo_node running and do
void Foo::init()
{
auto parameters_client = std::make_shared<rclcpp::SyncParametersClient>(this);
this->declare_parameter("foo");
auto sub = parameters_client->on_parameter_event(
[this](const rcl_interfaces::msg::ParameterEvent::SharedPtr event) -> void
{
for (auto & changed_param : event->changed_parameters)
if (changed_param.name == "foo")
{
RCLCPP_INFO(this->get_logger(), "Foo is set");
}
});
}
and when I run ros2 set param /foo_node foo true in another process, the callback is not triggered but instead it logs [INFO] [Logger]: Hey.
Any thoughts?
Asked: 2019-06-20 13:17:19 -0500
Seen: 1,068 times
Last updated: Jun 20 '19
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