Device Pin Data Change Trigger

The Device Pin Data Change trigger fires an automation rule every time a specific pin on a specific device receives a new value. It is the most common trigger type — ideal for threshold alerts, data-driven relay control, and any reaction to real-time sensor readings.

How It Works

Every time a data point arrives for the chosen device + pin combination — whether from the device's firmware over MQTT, from the dashboard UI, or from the REST/external API — the trigger fires and the rule is evaluated.

Device publishes V1 = 87.4
         │
         ▼
   Trigger fires
         │
         ▼
   Conditions checked (e.g. V1 > 80?)
         │
         ├─ PASS → Actions run (notification, pin set, webhook…)
         └─ FAIL → Rule exits silently

Every Data Point

The trigger fires on every incoming data point, even if the value has not changed. If your device sends 10 identical readings per second, the trigger fires 10 times per second.

Use a Cooldown (Step 5) to prevent action spam, and use Conditions (Step 3) to filter by value range rather than relying on the trigger to filter itself.

When to Use This Trigger

Use Case	Example
Threshold alert	Temperature pin V1 > 80 → send push notification
Relay control	Soil moisture A0 < 30 → turn on irrigation (D1 = 1)
Data-driven webhook	Vibration pin V3 changes → POST to external system
State tracking	Motion sensor D0 receives `1` → log and notify
Multi-pin correlation	Pressure V2 spikes AND temperature V1 > threshold (via Conditions)

Step-by-Step Setup

Step 1 — Basics

Give the rule a clear name (e.g. "High Temp Alert") and optionally a description. Select the Project that owns the device.

Step 2 — Trigger

Select Device Pin Data Change from the trigger type list.

Field	Description
Device	The device to watch. Only devices in the selected project are shown.
Pin	Which pin to monitor. Any virtual (`V0`–`V255`), digital (`D0`–`D15`), or analog (`A0`–`A7`) pin.

Once both are selected the trigger is configured. The rule will fire on the next data point for that device + pin.

Step 3 — Conditions (recommended for threshold rules)

Without conditions, the rule fires on every single data point. Add a condition to filter:

Example: only fire when V1 exceeds 80

Field	Value
Device	(same sensor device)
Pin	`V1`
Operator	`>`
Value	`80`

Available operators:

Operator	Meaning
`>`	Greater than
`≥`	Greater than or equal
`<`	Less than
`≤`	Less than or equal
`=`	Exactly equal
`≠`	Not equal
`between`	Value is between min and max (inclusive)
`Δ ≥`	Absolute change from previous value ≥ threshold

The Δ ≥ (delta) operator is especially useful here — fire only when the reading jumps by at least N rather than crossing a static threshold. Useful for vibration, pressure spikes, and rate-of-change alerts.

Step 4 — Actions

Action	Example use
Send Notification	Push alert to mobile app with current reading
Send Alarm	Looping alarm sound until dismissed
Set Pin Value	Turn relay on (`D0 = 1`) when threshold exceeded
Toggle Pin	Flip relay state
Delay	Wait N seconds between actions
Call Webhook	POST data to an external system
Send Email	Email alert (Pro+)

Use Template Variables in message bodies to embed the live pin value:

Temperature alert! Sensor reading: {{VW-KNZWRK:V1}}°C

Step 5 — Options

Option	Recommendation
Cooldown	Set to at least your device's publish interval to avoid repeated alerts on every reading
Active Time Window	Optional — restrict alerts to business hours (e.g. `08:00`–`22:00`)
Active Days	Optional — uncheck weekends to skip off-days
Timezone	Set to your local timezone when using time window or active days

Template Variables

In notification, alarm, and email message bodies you can reference pin values using:

{{<Device ID>:<pin>}}

The Device ID is the VW-XXXXXX identifier shown on the device detail page under Device Credentials.

Examples:

Placeholder	Renders as
`{{VW-KNZWRK:V1}}`	Current value of V1 (the trigger pin)
`{{VW-KNZWRK:V2}}`	Value of V2 (if used in a condition)
`{{VW-KNZWRK:D0}}`	Value of D0

Geofence variables

If you are using the GPS Geofence trigger, two additional variables are available: {{geofence_event}} and {{distance_m}}. See the GPS Geofence Trigger guide.

Firmware Examples

Arduino / ESP8266 / ESP32
Python / Raspberry Pi
REST API

#include <VwireIOT.h>

VwireIOT vwire;

void setup() {
  vwire.begin("VW-KNZWRK", "your-auth-token");
}

void loop() {
  // Read a temperature sensor (DS18B20, DHT22, etc.)
  float temp = readTemperature();   // your sensor read function

  // Push to virtual pin V1 — triggers any rule watching this pin
  vwire.virtualWrite(1, temp);

  delay(5000);  // publish every 5 s
}

import vwire
import time

client = vwire.Client("VW-KNZWRK", "your-auth-token")

while True:
    temp = read_temperature()       # your sensor read function
    client.virtual_write(1, temp)   # triggers any rule watching V1
    time.sleep(5)

# PUT a value to V1 — triggers any rule watching this pin
curl -X PUT https://api.vwire.io/api/v1/devices/VW-KNZWRK/pins/V1 \
  -H "Authorization: Bearer your-auth-token" \
  -H "Content-Type: application/json" \
  -d '{"value": "87.4"}'

Worked Example — High Temperature Alert with Relay Cutoff

Scenario: A server room temperature sensor publishes to V1 every 30 seconds. When it exceeds 30 °C, send an alarm push and cut power to non-essential loads by setting relay D0 to 0.

Field	Value
Name	Server Room High Temp
Project	Server Room
Trigger type	Device Pin Data Change
Device	RoomSensor01
Pin	V1
Condition	V1 > 30
Action 1	Send Alarm — "Server room at `{{VW-KNZWRK:V1}}`°C — relay disabled"
Action 2	Set Pin — RoomSensor01 / D0 = `0`
Cooldown	300 s (5 minutes — prevent re-firing every 30s while temp stays high)
Active Days	All days

Troubleshooting

Rule never fires

Confirm the device is online and actively publishing data. Check Device → Pin History to verify data is arriving.
Confirm the trigger's Device and Pin match exactly what the firmware is writing.
Check that the rule is enabled (green toggle on the rule card).
If using a cooldown, the rule may be suppressed. Check Logs on the rule card — a suppressed execution is not logged.

Rule fires too often

Add a Cooldown in Step 5 (e.g. 300 seconds for a 5-minute minimum gap).
Add a Condition with a threshold so the rule only runs when the value is actually interesting.

Condition never passes even though value seems correct

Conditions compare values as numbers when both sides parse as numbers. If your device sends a string like "ON" instead of 1, use = with ON.
The condition reads the current cached pin value from Redis, not the historical average. A rapid spike that comes and goes in < 1 second may be missed.

Template variable shows raw `{{...}}`

Double-check the Device ID (VW-XXXXXX) against the Device Credentials section on the device detail page.
Confirm the pin name matches exactly (V1 vs v1 — case-sensitive).
The variable is only substituted for devices involved in the trigger or conditions of this rule.

Summary

Property	Value
Fires when	A new data point arrives for the selected device + pin
Fires on unchanged values	Yes — every data point, regardless of value change
Supported pin types	Virtual (`V0`–`V255`), Digital (`D0`–`D15`), Analog (`A0`–`A7`)
Filter by value	Use Step 3 Conditions (`>`, `<`, `=`, `between`, `Δ≥`)
Spam prevention	Cooldown in Step 5 Options
Available plans	Free, Pro, Pro Plus, Enterprise

How It Works​

When to Use This Trigger​

Step-by-Step Setup​

Step 1 — Basics​

Step 2 — Trigger​

Step 3 — Conditions (recommended for threshold rules)​

Step 4 — Actions​

Step 5 — Options​

Template Variables​

Firmware Examples​

Worked Example — High Temperature Alert with Relay Cutoff​

Troubleshooting​

Rule never fires​

Rule fires too often​

Condition never passes even though value seems correct​

Template variable shows raw {{...}}​

Summary​