Simulator Guide

Goal: Test your workspace with simulated data before connecting real devices.

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What is the Simulator?

The OpenIndustrial simulator:

Feature	Description
Custom data	Configure any telemetry structure you need
Three tabs	Settings, Variables, and Template for full control
Customizable	Adjust data ranges, frequencies, device IDs
Instant	Data flows immediately after deployment

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Prerequisites

• Active workspace
• At least one data connection created

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Option A: Using the UI

Step 1: Add Simulator to Canvas

1. Locate the Simulator in the Node Bank (flask icon, top of the left panel)
2. Drag the Simulator onto the canvas

Step 2: Configure Settings

Click the Simulator node to open the Inspector. In the Settings tab:

Setting	Description	Example
Name	Simulator identifier	"BreweryTelemetry"
Message Interval (ms)	Milliseconds between messages	5000 (5 seconds)
Messages per Device	Total messages to send (0 = infinite)	0

Step 3: Define Variables

In the Variables tab, click Add Variable to create data points for things you want to simulate:

Variable Name	Type	Configuration
temperature	Random Integer	Min: 65, Max: 75
humidity	Random Integer	Min: 40, Max: 60
pressure	Random Float	Min: 14.5, Max: 15.5

Available variable types:

Type	Description
Static	Fixed value that never changes
Random Integer	Random whole number between min/max
Random Float	Random decimal between min/max
Incrementing	Increases by 1 each message

Step 4: Define Message Template

In the Template tab, use the UI to map your variables to the message structure. Define field names and assign your variables to each field.

The Template UI lets you visually build your message structure without writing JSON directly.

Step 5: Connect to Data Connection

1. Draw a line from the Simulator to your data connection node
2. The edge will show "simulates" label
3. Commit and deploy to start data flow

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Option B: Ask Azi

Example prompts:

• "Create a simulator for my connection with temperature and humidity"
• "Add a simulator to brew-data that sends pressure readings every 5 seconds"
• "Set up simulated telemetry for test-sensors"

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Verifying Data Flow

After attaching the simulator:

1. Click your data connection node
2. Open the Inspector panel (right side)
3. You should see impulses arriving:

{
  "timestamp": "2026-01-18T10:30:00Z",
  "deviceId": "sim-temp-01",
  "temperature": 72.5,
  "humidity": 45.2
}

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Customizing Simulator Output

You can adjust simulator behavior:

Setting	What It Controls
Frequency	How often data is generated (default: 5 seconds)
Device count	Number of simulated devices
Value ranges	Min/max for numeric fields
Noise	Randomness in generated values

To Customize:

1. Click the simulator node
2. Open Inspector
3. Adjust settings in the configuration panel
4. Changes apply immediately

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Troubleshooting

Issue	Solution
No data appearing	Check simulator is attached (line should connect to data connection) and deployed
Data stopped	Simulator may have been paused - check status in Inspector
Wrong data format	Update your Variables and Template tabs to match expected structure
Too much data	Increase the Message Interval (ms) in Settings tab

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Best Practices

1. Test queries first - Build warm queries against simulated data before production
2. Match data shapes - Configure simulators to match your real device schemas
3. Clean up - Detach simulators after testing to keep workspace tidy
4. Document settings - Note variable names and template structure for team members

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Custom Code Simulators

For more complex simulation scenarios, you can write your own simulator in any language that supports the Azure IoT Hub SDK:

Language	Package
TypeScript/JavaScript	@azure/iot-device
Python	azure-iot-device
C#	Microsoft.Azure.Devices.Client
Java	com.microsoft.azure.sdk.iot

Custom simulators connect the same way as real devices - using the device connection string from your Connection node.

Getting the Connection String

1. Click your Connection node to open the Inspector
2. Find the Device Connection String in the connection details
3. Use this string in your custom simulator code

Example: TypeScript Simulator

import { Client } from 'azure-iot-device';
import { Mqtt } from 'azure-iot-device-mqtt';

const connectionString = 'YOUR_DEVICE_CONNECTION_STRING';
const client = Client.fromConnectionString(connectionString, Mqtt);

async function sendTelemetry() {
  const message = {
    deviceId: 'custom-sensor-001',
    temperature: Math.random() * 10 + 65,
    humidity: Math.random() * 20 + 40,
    timestamp: new Date().toISOString()
  };

  await client.sendEvent(JSON.stringify(message));
  console.log('Sent:', message);
}

// Send every 5 seconds
setInterval(sendTelemetry, 5000);

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Next Steps

If you want to...	Go to...
Connect real devices	IoT Hub Guide →
Route data to surfaces	Surfaces Guide →
Build queries on this data	Warm Queries Guide →