Modbus_ROS2

Overview

A ROS 2 package for Modbus with TCP

Keywords: ROS 2, Modbus, Modbus TCP

License

The source code is released under a MIT license.

Installation

Dependencies

• Robot Operating System (ROS) 2 (middleware for robotics),
• libyaml-cpp-dev ,
• libmodbus-dev (Modbus library)

Building

cd ros2_workspace/src
git clone -b main --recursive https://github.com/Capacites/ros2_modbus.git
cd ..
colcon build --symlink-install --packages-select ros_modbus_msgs ros_modbus

Node

Architecture

The package provides a C++ node: ros2 run ros_modbus modbus_node

While continuously updating the state of the Modbus device's IOs, the node may publish two types of messages:

• The IO's state (on timer or on event depending on the configuration file)
• The node state (indicating wether published data should be considered valid or not, and a debug code)

Published Topics

• state ([ros_modbus_msgs/State])

  Publishes the node state in a custom message, the state will be published on timer and on event:

    std_msgs/Header header            # header info
    bool state                        # Data validity
    uint8 error 					  # error number
  

• report_timer ([ros_modbus_msgs/Modbus])

  Publishes in a custom message the IO values on timer callback for IOs configured as such in the configuration file:

    std_msgs/Header header            # header info
    string[] in_out                   # name of each I/O
    uint16[] values                   # value of each I/O
  

• report_event ([ros_modbus_msgs/Modbus])

  Publishes in a custom message the IO values on event callback for IOs configured as such in the configuration file:

    std_msgs/Header header            # header info
    string[] in_out                   # name of each I/O
    uint16[] values                   # value of each I/O
  

Subscribed Topics

• command ([ros_modbus_msgs/Modbus])

  Subscribes to commands, write the received values on the associated outputs of the device:

    std_msgs/Header header            # header info
    string[] in_out                   # name of each I/O
    uint16[] values                   # value of each I/O
  

Parameters

• sub_queue_size
  • Type: integer
  • Description: Queue size for subscribers
  • Default value: 10
• pub_queue_size
  • Type: integer
  • Description: Queue size for publisher
  • Default value: 5
• name
  • Type: string
  • Description: Name of the device, must be the same in the configuration file
  • Default value: test_device
• YAML_config_file
  • Type: string
  • Description: File containing the configuration to be loaded
  • Default value: FULL/PATH/TO/YOUR/config_file.yaml

Configuration file

A configuration file example can be found in ros_modbus/config as configuration.yaml