networktables_bridge

Overview

networktables_bridge provides a ROS 2 lifecycle node that bridges selected NetworkTables (NT4) keys into ROS 2 topics. The current implementation is a C++ lifecycle node that listens to AdvantageKit/SystemStats topics on NetworkTables and publishes a frc_msgs/msg/MiscReport message on the misc_report topic.

This README focuses on the C++ bridge present in this package (executable: nt_bridge_node).

What this node does

• Connects to a NetworkTables server (typically a roboRIO or NT server) as an NT4 client.
• Subscribes to AdvantageKit/SystemStats and NTClients keys and converts them into ROS 2 frc_msgs/msg/MiscReport and frc_msgs/msg/NTClient messages.
• Publishes misc_report (type frc_msgs/msg/MiscReport).

Note: the node implements the ROS 2 managed lifecycle (rclcpp_lifecycle). After launching, you must transition the node to the activate state for it to start publishing.

Build / Install

Prerequisites

• ROS 2 (tested with Humble / Iron)
• Colcon build tool and rosdep
• System dependencies for WPILib/ntcore when building the node (the CMake file links against ntcore, wpinet, wpiutil, wpimath). Ensure your environment provides these libraries if you need NT4 integration.

Typical steps

# from your ROS 2 workspace root
git clone <repo-url> src/networktables_bridge
rosdep install --from-paths src --ignore-src -r -y
colcon build --packages-select networktables_bridge
source install/setup.bash

If your environment is missing WPILib/ntcore libraries, follow WPILib/ntcore installation instructions for your platform or build those packages into the workspace.

Launching

This package provides a launch file: launch/nt_bridge.launch.py.

Launch with the default (localhost) NetworkTables server:

ros2 launch networktables_bridge nt_bridge.launch.py

Provide a different NetworkTables server IP (e.g., roboRIO at 10.80.20.2):

ros2 launch networktables_bridge nt_bridge.launch.py nt_server_ip:=10.80.20.2

You can also run the executable directly (useful for debugging):

ros2 run networktables_bridge nt_bridge_node --ros-args -p nt_server_ip:=10.80.20.2

Lifecycle notes

• The node is a lifecycle node and will not publish until it is transitioned into the active state. Use the ROS 2 lifecycle CLI to transition the node:

ros2 lifecycle set /nt_bridge_node configure
ros2 lifecycle set /nt_bridge_node activate

After activation the node will publish misc_report periodically (50 Hz step timer logic inside the node).

Parameters

• nt_server_ip (string, default: 127.0.0.1) — IP address of the NetworkTables server.
• nt_remote_id (string, default: node name) — remote id used when starting the NT client.

These are set in the launch file by default; pass different values via the launch arguments or --ros-args -p when running the executable.

Topics and messages

• Publishes: misc_report — type: frc_msgs/msg/MiscReport (contains team number, battery values, various rail voltages/currents, NT client list, timestamp, etc.)

The node maps values from AdvantageKit/SystemStats and NTClients NetworkTables keys into the fields of MiscReport and NTClient messages.

Development notes

• Executable: nt_bridge_node (defined in CMakeLists.txt).
• The node uses networktables_common helpers (see networktables_common/nt_pubsub.hpp) to subscribe to NT topics.
• CMake links against ntcore, wpinet, wpiutil, and wpimath — these must be available at link time.

License

This package is licensed under LGPLv3 (see package.xml).

Contributing

Contributions welcome — please open issues or PRs with changes. For build or runtime problems, include logs and platform details.