Use a parameter for the serial port

Author: stefanscherzinger

schunk_gripper_driver/launch/driver.launch.py

@@ -16,16 +16,30 @@
 
 from launch import LaunchDescription
 from launch_ros.actions import Node
+from launch.actions import DeclareLaunchArgument
+from launch.substitutions import LaunchConfiguration
+
+
+port = DeclareLaunchArgument(
+    "port",
+    default_value="/dev/pts/13",
+    description="The gripper's serial port",
+)
+args = [port]
 
 
 def generate_launch_description():
     return LaunchDescription(
-        [
+        args
+        + [
             Node(
                 package="schunk_gripper_driver",
                 namespace="schunk",
                 executable="driver.py",
                 name="driver",
+                parameters=[
+                    {"port": LaunchConfiguration("port")},
+                ],
             )
         ]
     )

schunk_gripper_driver/schunk_gripper_driver/driver.py

@@ -28,12 +28,13 @@ class Driver(Node):
 
     def __init__(self, node_name: str, **kwargs):
         super().__init__(node_name, **kwargs)
-        self.mb_client = ModbusSerialClient(
-            port="/dev/pts/13", baudrate=9600, timeout=1
-        )
+        self.declare_parameter("port", rclpy.Parameter.Type.STRING)
+        self.port = self.get_parameter_or("port", "/dev/ttyUSB0").value
+        self.mb_client = ModbusSerialClient(port=self.port, baudrate=9600, timeout=1)
 
     def on_configure(self, state: State) -> TransitionCallbackReturn:
         self.get_logger().info("on_configure() is called.")
+        self.get_logger().info(f"Connecting on port {self.port}")
         if not self.mb_client.connect():
             self.get_logger().warn("Modbus client connect failed")
             return TransitionCallbackReturn.FAILURE