MQTT Communication Setup

This guide shows you how to configure MQTT communication between your OV20i camera and external devices using Node-RED. MQTT enables lightweight, reliable messaging for IoT applications and remote device communication.

When to Use MQTT Communication: IoT device integration, remote monitoring systems, publish/subscribe messaging patterns, low-bandwidth environments, distributed sensor networks, or when you need reliable message delivery with automatic reconnection.

Prerequisites

• OV20i camera system set up and connected
• Network connectivity between camera and MQTT broker
• MQTT broker available (local or cloud-based)
• Basic understanding of MQTT concepts (topics, publish/subscribe)
• Active recipe configured on the camera

MQTT Communication Overview

MQTT Key Concepts:

• Broker: Central server that routes messages between clients
• Topics: Message categories (e.g., "camera/status", "commands/trigger")
• Publish: Send messages to a topic
• Subscribe: Receive messages from a topic
• QoS: Quality of Service levels (0, 1, 2)

Step 1: Verify Network Configuration

1.1 Check Camera Network Settings

1. Navigate to System Settings
2. Note camera IP address (e.g., 192.168.0.100)
3. Verify network connectivity to MQTT broker

1.2 MQTT Broker Requirements

Ensure MQTT broker accessibility:

• Same network: Camera must reach broker IP address
• Port access: Default MQTT port 1883 (or 8883 for TLS)
• Authentication: Username/password if broker requires it
• Firewall: Allow MQTT traffic on required ports

1.3 Network Requirements

Component	IP Address	Port	Notes
Camera	192.168.0.100	N/A	Must reach broker
MQTT Broker	192.168.0.200	1883	Standard MQTT port
Client Devices	192.168.0.xxx	Variable	Any devices subscribing

Step 2: Access Node-RED Editor

2.1 Navigate to IO Block

1. Open your active recipe in Recipe Editor
2. Click "IO Block" in breadcrumb menu
3. Click "Configure IO" to enter Node-RED editor

2.2 Verify MQTT Nodes Available

Check Node-RED palette for MQTT nodes:

• mqtt in - Subscribe to MQTT topics
• mqtt out - Publish to MQTT topics

Checkpoint: You should see MQTT nodes in the Network section of the left panel.

Step 3: Configure MQTT Broker Connection

3.1 Add MQTT Broker Configuration

1. Drag "mqtt in" node onto canvas (for initial setup)
2. Double-click the node to open configuration
3. Click pencil icon next to Server field
4. Click "Add new mqtt-broker"

3.2 Configure Broker Settings

Basic Broker Configuration:

Setting	Value	Description
Name	Camera MQTT Broker	Descriptive identifier
Server	192.168.0.200	MQTT broker IP address
Port	1883	Standard MQTT port
Protocol	MQTT V3.1.1	Recommended version
Client ID	(auto-generate)	Leave blank for automatic

3.3 Authentication Settings (If Required)

If broker requires authentication:

Setting	Description
Username	MQTT broker username
Password	MQTT broker password
Use TLS	Enable for secure connections (port 8883)

3.4 Advanced Settings

Connection Options:

Setting	Recommended Value	Description
Keep Alive	60 seconds	Heartbeat interval
Clean Session	True	Start fresh each connection
Auto Connect	True	Reconnect automatically

3.5 Save Broker Configuration

1. Click "Add" to save broker settings
2. Click "Done" to close node configuration
3. Broker configuration is now available for all MQTT nodes

Step 4: Configure MQTT Input (Subscribe)

4.1 Set Up MQTT In Node

1. Select the "mqtt in" node you added
2. Double-click to configure
3. Configure subscription settings:

4.2 MQTT In Configuration

Subscription Settings:

Setting	Example Value	Description
Server	Camera MQTT Broker	Select configured broker
Topic	camera/commands	Topic to subscribe to
QoS	0	Message delivery quality
Output	auto-detect	Message format
Name	Command Listener	Node identifier

4.3 Topic Naming Conventions

Recommended topic structure:

Purpose	Topic Example	Usage
Commands	camera/commands	Receive control commands
Status requests	camera/status/request	Status information requests
Configuration	camera/config	Configuration changes

4.4 Configure Message Processing

1. Add "debug" node to monitor incoming messages
2. Connect: MQTT In → Debug
3. Configure debug node to show complete message

Step 5: Configure MQTT Output (Publish)

5.1 Add MQTT Out Node

1. Drag "mqtt out" node onto canvas
2. Double-click to configure
3. Select same broker configuration

5.2 MQTT Out Configuration

Publishing Settings:

Setting	Example Value	Description
Server	Camera MQTT Broker	Same broker as input
Topic	camera/responses	Topic for camera responses
QoS	0	Message delivery quality
Retain	False	Don't store last message
Name	Response Publisher	Node identifier

5.3 Response Topic Structure

Recommended response topics:

Response Type	Topic Example	Usage
Status updates	camera/status	Camera status information
Results	camera/results	Inspection results
Acknowledgments	camera/ack	Command confirmations

Step 6: Create Basic Communication Flow

6.1 Build Outgoing Message Flow

Create a flow to publish messages from the camera:

1. Add "inject" node for triggering messages
2. Add "function" node for message formatting
3. Add "mqtt out" node for publishing
4. Connect: Inject → Function → MQTT Out

6.2 Build Incoming Message Flow

Create a separate flow to receive messages:

1. Add "mqtt in" node for subscribing
2. Add "debug" node for monitoring
3. Connect: MQTT In → Debug

6.3 Configure Inject Node

1. Double-click inject node
2. Configure settings:
   • Name: "Send Test Message"
   • Payload: Timestamp
   • Topic: (leave empty)
3. Click "Done"

6.4 Configure Function Node

Simple message formatting:

// Format outgoing message
msg.topic = "camera/status";
msg.payload = "Camera online - " + new Date().toISOString();
return msg;

1. Double-click function node
2. Copy code above into "On Message" tab
3. Name: "Format Message"
4. Click "Done"

6.5 Configure MQTT Out Node

1. Double-click mqtt out node
2. Select broker: Camera MQTT Broker (configured earlier)
3. Topic: (leave empty - set by function node)
4. Name: "Publish Status"
5. Click "Done"

6.6 Configure MQTT In Node

1. Double-click mqtt in node
2. Select broker: Camera MQTT Broker
3. Topic: camera/commands
4. Name: "Command Listener"
5. Click "Done"

6.7 Configure Debug Node

1. Double-click debug node
2. Output: Complete msg object
3. Name: "Incoming Messages"
4. Click "Done"

6.8 Final Flow Structure

Your complete flow should be:

Outgoing: Inject → Function → MQTT Out Incoming: MQTT In → Debug

Step 7: Deploy and Test Configuration

7.1 Deploy Flow

1. Click "Deploy" button (top-right corner)
2. Verify deployment success message
3. Check node status indicators:
   • Green dot: Connected to broker
   • Red dot: Connection failed
   • Yellow dot: Connecting

7.2 Test Internal Communication

Test the camera's MQTT publishing:

1. Click inject button to send test message
2. Verify MQTT Out node shows activity
3. Check debug panel if you have external messages

7.3 External Testing (Optional)

Test with external MQTT client to send commands to camera:

Using command line tools:

# Send a test command to the camera
mosquitto_pub -h 192.168.0.100 -t "camera/commands" -m "test_command"

Expected result: Debug node should show the incoming message in Node-RED debug panel.

7.4 Verify Communication

Check these aspects:

Test	Expected Result	Status
Broker connection	Green status on MQTT nodes	☐
Message publishing	Inject triggers MQTT Out successfully	☐
Message reception	Debug shows external messages	☐
Reconnection	Auto-reconnect after network interruption	☐

Step 8: Troubleshooting MQTT Issues

8.1 Connection Problems

Problem	Symptoms	Solution
Cannot connect to broker	Red status indicators	Check broker IP and port
Authentication failure	Connection refused	Verify username/password
Network timeouts	Yellow connecting status	Check network connectivity
Firewall blocking	No connection attempt	Open MQTT ports

8.2 Message Issues

Problem	Symptoms	Solution
No messages received	Debug shows nothing	Check topic subscriptions
Messages not publishing	External clients see nothing	Verify publish topics
Message format errors	Parsing failures	Use simple text messages
Lost messages	Intermittent delivery	Check broker connection

8.3 Performance Issues

Problem	Symptoms	Solution
High latency	Delayed message delivery	Check broker performance
Connection drops	Frequent reconnections	Adjust keep-alive settings
Message flooding	Broker overload	Implement message throttling

8.4 Debug Techniques

Systematic troubleshooting:

1. Check broker connection status in Node-RED
2. Monitor Node-RED debug panel for message flow
3. Use simple text messages before complex data
4. Verify network connectivity with ping
5. Test with basic topics before advanced flows

Success! Your MQTT Communication is Ready

Your MQTT communication system can now:

• Connect to MQTT brokers with proper authentication
• Subscribe to topics for receiving commands and data
• Publish messages for status updates and responses
• Handle JSON message formats for structured communication
• Automatically reconnect after network interruptions
• Support multiple QoS levels for different message priorities

Ongoing Maintenance

Regular System Checks

• Monitor broker connection status in Node-RED
• Verify message delivery with test messages
• Check broker logs for any error patterns
• Update authentication credentials as needed

Performance Monitoring

• Track message latency and delivery times
• Monitor broker resource usage for scalability
• Analyze topic usage patterns for optimization
• Review QoS settings based on actual requirements

Next Steps

After setting up basic MQTT communication:

1. Implement specific messaging workflows for your application
2. Set up topic hierarchies for organized communication
3. Add security measures like TLS encryption
4. Integrate with external systems using established MQTT protocols
5. Create monitoring dashboards for system health

🔗 See Also

• Trigger over MQTT
• TCP Communication Setup
• RS-232 Communication Setup
• Connect to PLC ( Ethernet/IP, PROFINET)
• Node-RED Basics