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Your First Node-RED Flow

Conceptual introduction to creating and deploying flows on IRIV PiControl.

What is a Flow?​

A Node-RED flow is a visual representation of connected nodes that process data and execute actions. Each flow consists of:

Nodes: Individual functional blocks (inputs, outputs, functions, logic) Wires: Connections between nodes that define data flow Messages: Data packets passed between nodes

Pre-Configured Dashboard​

The IRIV PiControl ships with a default dashboard flow that demonstrates basic functionality:

Control elements:

  • Buttons to control digital outputs (DO0-DO3)
  • LED control switches (LED0, LED1)
  • Buzzer activation button
  • Safe shutdown button (hold User Button for 5 seconds)

Monitoring elements:

  • Display system status on OLED
  • Show IP addresses
  • Monitor device states

Access: Navigate to iriv.local:1880/ui to interact with the pre-configured dashboard.

Flow Structure Overview​

A typical IRIV PiControl flow includes:

Input Nodes​

  • Inject nodes (manual triggers, timers)
  • GPIO input nodes (digital inputs DI0-DI3)
  • Dashboard button/switch nodes
  • Serial port input (RS485, RS232)

Processing Nodes​

  • Function nodes (JavaScript processing)
  • Switch nodes (conditional routing)
  • Change nodes (message modification)
  • Template nodes (data formatting)

Output Nodes​

  • GPIO output nodes (digital outputs DO0-DO3, LEDs, buzzer)
  • Dashboard display nodes
  • Serial port output
  • Debug nodes (development/troubleshooting)

Basic Flow Concepts​

Triggering Actions​

Manual trigger:

  • Inject node provides a button in the editor
  • Dashboard button node creates UI control element

Timed trigger:

  • Inject node configured with interval
  • Used for periodic sensor readings, status updates

Event trigger:

  • GPIO input node responds to digital input state changes
  • Dashboard input nodes respond to user interaction

Processing Data​

Function nodes:

  • Execute custom JavaScript code
  • Process sensor data, apply calculations
  • Format messages for output

Logic nodes:

  • Switch nodes route based on conditions
  • Filter nodes pass/block messages

Controlling Outputs​

GPIO control:

  • GPIO output node sets pin HIGH/LOW
  • Controls digital outputs, LEDs, buzzer

Display output:

  • Dashboard nodes update UI elements
  • OLED display updates via I2C function nodes

Deploying a Flow​

After creating or modifying a flow:

  1. Click "Deploy" button in the Node-RED editor
  2. Changes take effect immediately
  3. Test functionality via dashboard or direct interaction

Deploy options:

  • Full (deploys all flows)
  • Modified flows (only changed flows)
  • Modified nodes (only changed nodes)

Editing Existing Flows​

The pre-configured dashboard can be modified:

  1. Access editor: Navigate to http://iriv.local:1880
  2. View flows: Existing flows appear in the workspace
  3. Modify nodes: Double-click nodes to edit configuration
  4. Add connections: Drag between node output and input ports
  5. Deploy changes: Click Deploy button

Example Flow Pattern: Button Controls LED​

Conceptual flow structure:

[Dashboard Button] --> [Function: Toggle] --> [GPIO Output] --> LED0

Flow behavior:

  1. User clicks button on dashboard
  2. Function node toggles state (ON/OFF)
  3. GPIO output node sets GPIO20 HIGH or LOW
  4. LED0 illuminates or turns off

Step-by-step implementation instructions are available in the official hands-on tutorial.

Debugging Flows​

Debug nodes:

  • Display message content in the debug panel
  • Monitor data flow between nodes
  • Troubleshoot logic issues

Debug panel access:

  • Located on right side of Node-RED editor
  • Shows real-time message output from debug nodes

Flow Best Practices​

Descriptive naming:

  • Label nodes with clear, meaningful names
  • Group related functionality into separate flows

Modular design:

  • Create reusable subflows for common operations
  • Keep individual flows focused on specific tasks

Error handling:

  • Include catch nodes for error management
  • Validate input data before processing

Documentation:

  • Use comment nodes to annotate flow purpose
  • Document complex logic in function nodes

Learning Resources​

Official Hands-On Tutorial: IRIV PiControl Node-RED Tutorial

This beginner-friendly, 13-part series covers:

  • Basic flow creation
  • Dashboard design
  • GPIO control
  • Industrial integration

Node-RED Documentation:

  • Official Node-RED guides
  • Node library reference
  • Community cookbook examples

Next Steps​

  1. Explore industrial use cases
  2. Follow the hands-on tutorial for detailed implementation
  3. Experiment with the pre-configured dashboard
  4. Create custom flows for your application

Source(s):

  • IRIV PiControl Node-RED Tutorial (my.cytron.io)
  • IRIV PiControl CM4 User Manual, Rev 1.3, Nov 2025