ROS2 Service Server: Reset Counter

Lab 01 – ROS2 Service Server Implementation

• Nombre del proyecto: ROS2 Service Server (Lab 01)
• Equipo / Autor(es): Isaac Antonio Pérez Alemán
• Curso / Asignatura: Applied Robotics
• Fecha: 19/02/2026

---

1. Activity Goals

• Add a functionality to reset the counter to zero.
• Create a Service Server: Create a service server inside the existing number_counter node.
• Name the service: /reset_counter.
• Service Type: Use the isaac_interfaces/srv/SetBool type.
• When the server is called, check the boolean data from the request; if it is true, set the counter variable to 0.
• Call the service directly from the command line.
• Create a custom node to call the /reset_counter service for extra practice.

---

3. Materials

• No materials required

---

4. Code

4.1. Package (package.xml)

In this part, we have to add the necessary dependencies in our package.xml:

<?xml version="1.0"?>
<?xml-model href="[http://download.ros.org/schema/package_format3.xsd](http://download.ros.org/schema/package_format3.xsd)" schematypens="[http://www.w3.org/2001/XMLSchema](http://www.w3.org/2001/XMLSchema)"?>
<package format="3">
  <name>my_robot</name>
  <version>0.0.0</version>
  <description>TODO: Package description</description>
  <maintainer email="isaac_aleman_@todo.todo">isaac_aleman</maintainer>
  <license>TODO: License declaration</license>

  <depend>example_interfaces</depend>
  <depend>rclpy</depend>
  <depend>my_robot</depend>
  <depend>isaac_interfaces</depend>

  <test_depend>ament_copyright</test_depend>
  <test_depend>ament_flake8</test_depend>
  <test_depend>ament_pep257</test_depend>
  <test_depend>python3-pytest</test_depend>

  <export>
    <build_type>ament_python</build_type>
  </export>
</package>

4.2. Node Logic & Callback Analysis

Before writing the full code, we define the node class IsaacCounter(Node) and create the function for the callback. The callback evaluates the boolean request.data: - If True: It resets the counter to 0, logs the event, and returns a success response (True) with a confirmation message. - If False: It takes no action and returns a response indicating the reset was not performed (False).

4.3. Full Node Code (isaac_counter.py)

python
#!/usr/bin/env python3
import rclpy
from rclpy.node import Node
from isaac_interfaces.msg import Int64 
from isaac_interfaces.srv import SetBool

class numCounter(Node):
    def __init__(self):
        # Initialize node with the name "isaac_counter"
        super().__init__("isaac_counter")

        # Creates a service server type SetBool. (Service type, service name, callback function)
        self.server_ = self.create_service(SetBool, "/reset_counter", self.read_bool_callback) 

        # Start the counter on 0
        self.counter = 0 

        # (Type, topic name, callback function, queue size)
        self.subscriber = self.create_subscription(Int64, "/number", self.callback_receive_info, 10) 

        # (Type, topic name, queue size)
        self.publisher = self.create_publisher(Int64, "/number_count", 10) 

    # Subscriber callback. Triggers every time a message is received on /number. 
    # Adds the received value to the internal counter and publishes the updated total.
    def callback_receive_info(self, msg: Int64):
        # Accumulate received value
        self.counter += msg.data

        # Create message to publish
        out_msg = Int64()
        out_msg.data = self.counter

        # Log received value and current counter state
        self.get_logger().info(f"Received: {msg.data} | Counter: {self.counter}") 

        # Published updated counter value
        self.publisher.publish(out_msg)

    # Service callback for /reset_counter. If request.data is true, reset the counter to 0.
    def read_bool_callback(self, request, response):
        # Boolean condition
        if request.data:
            # reset counter
            self.counter = 0
            # Indicates successful reset
            response.success = True
            response.message = "Counter reset to 0"
            # Log reset event
            self.get_logger().info("Counter restarted to 0")
        else:
            # No reset performed
            response.success = False
            response.message = "Counter not reset"

        return response

def main(args=None):
    rclpy.init(args=args)        # Initialize rclpy
    counter_node = numCounter()  # Create node instance
    rclpy.spin(counter_node)     # Keep the node alive and processing callbacks
    rclpy.shutdown()             # Shutdown rclpy

if __name__ == "__main__":
    main()

4.4. Workspace Configuration (setup.py)

python
from setuptools import find_packages, setup

package_name = 'my_robot'

setup(
    name=package_name,
    version='0.0.0',
    packages=find_packages(exclude=['test']),
    data_files=[
        ('share/ament_index/resource_index/packages',
            ['resource/' + package_name]),
        ('share/' + package_name, ['package.xml']),
    ],
    install_requires=['setuptools'],
    zip_safe=True,
    maintainer='isaac_aleman',
    maintainer_email='isaac_aleman@todo.todo',
    description='TODO: Package description',
    license='TODO: License declaration',
    extras_require={
        'test': [
            'pytest',
        ],
    },
    entry_points={
        'console_scripts': [
            'C3P0 = my_robot.my_first_node:main',
            'number_publisher = my_robot.number_publisher:main',
            'number_counter = my_robot.number_counter:main',
            'c3p0 = my_robot.c3p0:main',
            'publisher = my_robot.publisher:main',
            'listener=my_robot.listener:main',  
            'todayclas = my_robot.todayclas:main',
            'status_pub = my_robot.status_pub:main',
            'num_publisher = my_robot.number_publisher:main',
            'num_counter = my_robot.number_counter:main', 
        ]
    }
)

---

5. Execution & Testing

First, we run the nodes for the publisher and the counter in separate Ubuntu terminals:

bash
# Terminal 1: Run the publisher
ros2 run my_robot num_publisher

# Terminal 2: Run the counter
ros2 run my_robot num_counter

Then, we test the reset function by calling the service directly from the command line:

bash
# Terminal 3: Call the reset service
ros2 service call /reset_counter isaac_interfaces/srv/SetBool "{data: true}"

---

Architecture Diagram