trigger

Overview

The trigger node creates timed message patterns. When triggered, it can immediately send an initial payload, wait for a configurable delay, then send a second payload. It supports three modes: send-then-wait, wait-then-send, and resettable timer. This makes it ideal for timeout patterns, watchdog timers, debouncing, and state-based automation.

Properties

Trigger Modes

// t=0: Send "ON" (1)
// t=5s: Send "OFF" (0)
// Great for: lights, alarms

// t=0: Start timer (no output)
// t=5s: Send payload
// Great for: debounce, cooldown

// Each msg resets the timer
// Only fires after silence
// Great for: watchdog, inactivity

Example: Motion Sensor Light Timer

Turn on a light immediately when motion is detected, then turn it off after 5 minutes of inactivity.

// Trigger node configuration
{
  "op": "send-wait",
  "initialPayload": 1,          // Send ON immediately
  "secondPayload": 0,           // Send OFF after delay
  "delay": 300000,              // 5 minutes (300,000 ms)
  "extend": true,               // Reset timer on new motion
  "reset": true                 // Allow manual reset
}

// Flow: [Motion Sensor] -> [Trigger] -> [Light Control]
//
// Timeline:
// 10:00:00 - Motion detected -> Light ON, timer starts (5 min)
// 10:02:30 - Motion detected -> Timer extends to 10:07:30
// 10:04:00 - Motion detected -> Timer extends to 10:09:00
// 10:09:00 - No more motion  -> Light OFF
//
// Output at 10:00:00: { "payload": 1 }  (ON)
// Output at 10:09:00: { "payload": 0 }  (OFF)

Example: Watchdog Timer

Alert when a sensor stops sending data for more than 60 seconds.

// Trigger node configuration (resettable watchdog)
{
  "op": "wait-send",
  "secondPayload": {
    "alert": "Sensor offline",
    "severity": "warning"
  },
  "delay": 60000,               // 60 seconds timeout
  "extend": true,               // Each heartbeat resets timer
  "reset": false
}

// Flow: [Sensor MQTT] -> [Trigger] -> [Alert Handler]
//
// Normal operation:
// - Sensor sends data every 10 seconds
// - Each message resets the 60-second timer
// - Trigger never fires
//
// Sensor failure:
// - Last message at t=0
// - No messages for 60 seconds
// - Trigger fires at t=60s with alert payload
// - Alert Handler sends email / dashboard notification

Common Use Cases