ROS 2 package for interfacing serial devices

The serial interface node reads data from a serial port at a fixed rate, and publishes it as string with timestamp.

Requirements

• Ubuntu 20.04 LTS (Focal Fossa) or later
• ROS 2 Foxy Fitzroy or later
• install serial library for c++

  git clone https://github.com/RoverRobotics-forks/serial-ros2
  cd serial-ros2/
  make
  make install
  cd ~/dev_ws/ && colcon build --packages-select serial
  

Download

Clone the repository to your ROS 2 workspace

git clone https://github.com/RozaGkliva/ros2_serial.git

Usage

1. Create a yaml configuration file to declare the parameters and their attributes

   ~/<PATH_TO_THIS_REPO>/ros_cppserial/config/<device_name>.yaml
   

   Parameters (with example values):

   node_name:
     ros__parameters:
       serial_params:
         use_port: False             # if True, the serial port will be used to connect to a device
         port: "/dev/ttyS2"          # if the port is fixed it should be used instead of device_hwid
         baud: 115200
         device_hwid: "0403:6001"    # if the port is not fixed the serial interface node will scan the ports for a device with a specific hardware id
       incoming_message:
         header: "N26"               # set if the packet contains a header
         footer: "/r/n"              # set if the packet contains a footer
         packet_size: 0
         rate_hz: 50                 # determines the rate of polling the serial port
       outgoing_message:
         is_single: False 
         is_continuous: False
         message: "r"                # specific to ATI FT sensor: "s" for continuous reading, "r" for single reading 
         rate_hz: 100                # 100 Hz
       publish_topic:
         name: "sensor_data"
         frame_id: "sensor_id"

   The node names should follow the following scheme: <device_name>_interface. When launching the nodes the same <device_name> will be used to create the node names and to look for parameter yaml files.

2. Build the packages with colcon.

   cd ~/<path to workspace>
   colcon build --path ~/<PATH_TO_THIS_REPO>/* --symlink-install
   

3. With your devices connected, run the interface:

   ros2 launch ros2_cppserial multi_serial_interface.launch.py names:=device_names
   

   where 'device_names' is a comma-separated list of device names, e.g.,

   ros2 launch ros2_cppserial multi_serial_interface.launch.py names:='gps,axia80'
   

   will launch two nodes: gps_interface and axia80_interface, and will look for gps.yaml and axia80.yaml respectively.

Roadmap

• Write script that finds the serial port A script is not necessary. Added command in guide.
• Add Arduino example (check: using parameters from yaml to set up communications - https://arduinojson.org/); use .amentignore in Arduino directory
• Make node flexible with parameters in yaml file
• Published message type can be set in yaml, the actual message type can be defined in ros2_serial_interfaces, TODO: look into parsing the packet and populating the message (can I look into the message type to plan the parsing?)
• c++ version works better and faster. Consider removing the python version
• license got messed up when the repository structure changed. TODO: FIX!
• Hydromasts have set serial ports, gps does not but has a serial hardware id
• Clear buffer until recent message appears (there seem to be some old/incomplete packets in the buffer)

Notes

• As of March 2024 the python package (ros2_pyserial) is no longer updated as the c++ version was more stable and at least twice as fast.
• As of July 2024 the python package has been removed.