Node RED flow development for DEXI

You want to make sure you don't lose any of your flow development. Make sure to map the host "flows" directory to the container directory as shown below. This will store the flow on your host machine if/when the container is destroyed.

Running on Physical Hardware (default)

docker run -it -p 1880:1880 -v ${PWD}/flows:/data --name dexi-node-red droneblocks/dexi-node-red:latest

Running in Simulation Environment

For simulation environments, override the websocket URL:

docker run -it -p 1880:1880 -e ROS2_WEBSOCKET_URL=ws://ros2-dev:9090 -v ${PWD}/flows:/data --name dexi-node-red droneblocks/dexi-node-red:latest

The default websocket URL is ws://192.168.4.1:9090 (physical hardware). Set the ROS2_WEBSOCKET_URL environment variable to customize for different environments.

Node RED custom node development for DEXI

1. Clone the repo:

git clone https://github.com/droneblocks/node-red-dexi

cd node-red-dexi

2. Launch the container from the base node-red image:

docker run -it -p 1880:1880 -v ${PWD}/flows:/data -v ${PWD}:/node-red-dexi --name dexi-node-red nodered/node-red:latest-debian

3. Connect to the container

docker exec -it dexi-node-red /bin/bash

4. First, install the package dependencies in the mapped directory

cd /node-red-dexi
npm install

5. Install the nodes for local development since we already mapped the host folder node-red-dexi to the container folder /node-red-dexi

cd /usr/src/node-red
npm install /node-red-dexi

6. Install other nodes

npm install node-red-contrib-ui-led
npm install node-red-node-ui-iframe

7. Stop and start container to pick up changes.

Shipped flows

flows/flows.json holds these tabs. Every tab and dashboard page ships disabled: enabled subscriptions stream PX4 topics through rosbridge from first boot whether or not anyone is watching, which cost an ARK CM4 most of a core. Enable a tab from its properties and Deploy.

| Tab | What it does | Runs on | |---|---|---| | 1 · Start Here | PX4 telemetry on the dashboard, LED ring color and effects | sim and drone | | 2 · Fly with the Offboard Manager | arm, take off, move and land through /dexi/offboard_manager | sim and drone | | 3 · AprilTags and YOLO | detections lighting the LED ring | AprilTags on both, YOLO on the drone | | 4 · Tag Navigation | the tag-hop mission and its dashboard | sim and drone | | 5 · AVR 2026 | the competition YOLO flow | drone | | 6 · Compute Kit (drone only) | servo, GPIO and laser pulse | drone |

DEXI Tag Navigation flow

flows/flows.json includes the DEXI Tag Navigation tab and its dashboard (/ui). One generic command node drives the on-board tag_nav and px4_offboard_manager services. The mission is a list of tag ids in the mission (steps as data) function node. The dashboard shows the camera, the tag in view, and ENGAGE, DISENGAGE, LAND and RESET buttons.

It needs tag_nav (dexi_apriltag) and the offboard manager (dexi_offboard) running on the aircraft or in the sim; dexi_apriltag documents the command contract they share.

flows/examples/tag_navigation.json is the same tab as an import file. Node-RED loads only flows.json; the files in flows/examples/ are for importing and do not appear as tabs on their own.