sas_datalogger

Tip

Repository for this module: https://github.com/SmartArmStack/sas_datalogger
More information about SmartArmStack is available at https://smartarmstack.github.io/.

Quick start

mkdir -p ~/sas_datalogger/docker/sas_datalogger_example
cd ~/sas_datalogger/docker/sas_datalogger_example
curl -OL curl -OL https://raw.githubusercontent.com/SmartArmStack/sas_datalogger/refs/heads/jazzy/docker/sas_datalogger_example/compose.yml

docker compose up

Important

To stop, press Ctrl + C. Do not forget to remove the containers:

docker compose down -v

The saved .mat file will be located at ~/sas_datalogger/docker/sas_datalogger_example/logs.

ROS 2 Nodes & Parameters

This package provides a datalogger server and suitable client APIs in C++ and Python. Each node is launched through its own launch file, which loads parameters from config/config.yaml (pass a different file with config_file:=/path/to/config.yaml).

Node: sas_datalogger

Property	Value
Executable	sas_datalogger_node.py
ROS node name	sas_datalogger (set by the name launch argument of sas_datalogger_launch.py)
Description	Main datalogger node. Subscribes to /sas_datalogger/log and stores received values in memory. When the node is shut down it saves the collected data to a MATLAB-compatible .mat file (via scipy.io.savemat).

Parameters

The server declares no ROS parameters — it subscribes to the fixed topic /sas_datalogger/log.

Sample launch

ros2 launch sas_datalogger sas_datalogger_launch.py

Node: sas_datalogger_gui_node

Property	Value
Executable	sas_datalogger_gui_node.py
ROS node name	sas_datalogger_gui_node (set by the name launch argument of sas_datalogger_gui_launch.py)
Description	A Qt-based GUI that reads the datalogger's internal dictionary and creates execution-time plots for numeric values.

Parameters

Parameter	Type	Mandatory / Optional	Default	Purpose
whitelist	string array	Optional	[' ']	List of values to plot. The single-space entry [' '] is the package convention for "plot all values" (the node maps it to None)

Sample launch

ros2 launch sas_datalogger sas_datalogger_gui_launch.py

To plot only specific values:

ros2 launch sas_datalogger sas_datalogger_gui_launch.py config_file:=/path/to/config.yaml

Node: sas_datalogger_client_example (C++ example client)

Property	Value
Executable	sas_datalogger_client_example
ROS node name	sas_datalogger_client_example (set by the name launch argument of sas_datalogger_client_cpp_example_launch.py)
Description	C++ example client. Publishes matrices, vectors, scalars and strings to the datalogger topic.

Parameters

The C++ example client declares no ROS parameters.

Sample launch

ros2 launch sas_datalogger sas_datalogger_client_cpp_example_launch.py

Node: sas_datalogger_client_example_py_rclpy (Python example client)

Property	Value
Executable	sas_datalogger_client_example_py.py
ROS node name	sas_datalogger_client_example_py_rclpy (fixed in the script; the script creates two nodes, so no name launch argument is set)
Description	Python example client. Publishes matrices, vectors, scalars and strings to the datalogger topic.

Parameters

Parameter	Type	Mandatory / Optional	Default	Purpose
execution_times	integer	Optional	5	How many times the example logs the sample values

Sample launch

ros2 launch sas_datalogger sas_datalogger_client_python_example_launch.py

Note

The Python example client executable creates two nodes (an rclcpp node and an rclpy node). The execution_times parameter is declared on the rclpy node, whose fixed code name is sas_datalogger_client_example_py_rclpy; the corresponding block in config/config.yaml is keyed by that name.