INDUSTRIAL DATA INTEGRATION
Modbus to MQTT Gateway
vNode is a software Modbus to MQTT gateway that reads data from Modbus TCP and Modbus RTU devices and publishes it to MQTT brokers. It provides a configurable, no-code path from industrial registers to MQTT topics, with Store&Forward for resilient delivery and support for on-premise and cloud-connected architectures.
From Modbus to MQTT — with vNode
Collect industrial data from Modbus devices, process it in vNode, and publish it to any MQTT broker.
1 Connect Modbus Devices
Read data from Modbus TCP or Modbus RTU devices (PLCs, HMIs, I/O, meters, drives).
Modbus TCP
Modbus RTU
2 Collect & Process
vNode acquires the data, maps and transforms it (scaling, filtering, formatting).
MQTT Publish
3 Publish to MQTT
Data is published to MQTT topics and ready for your IT, cloud or applications.
HOW IT WORKS
How Does a Modbus to MQTT Gateway Work?
vNode bridges the polling model used by Modbus devices with the publish/subscribe model used by MQTT applications.
1 Connect
Connect to Modbus TCP devices over Ethernet or Modbus RTU devices over serial communications.
2 Read
Poll coils, inputs and registers and expose them as meaningful industrial tags.
3 Map
Organize the data for MQTT topics and structured payloads required by downstream applications.
4 Publish
Send the resulting data to an on-premise or cloud-connected MQTT broker.
PROTOCOL BRIDGE
Why Modbus Needs a Gateway to Communicate with MQTT
vNode bridges the two: it polls Modbus so MQTT applications never have to.
Modbus. Device-level industrial protocol. A client/master polls addresses such as coils and holding registers from PLCs, meters, drives and controllers.
MQTT. Broker-based publish/subscribe messaging. Applications consume data through topics and payloads without polling the field device directly.
Modbus TCP, RTU and Register Mapping
Modbus TCP to MQTT
vNode connects to Modbus TCP devices over Ethernet using the device IP address, TCP port and unit/slave ID, polling holding registers, input registers, coils and discrete inputs. The resulting tags are mapped to MQTT topics and published to any on-premise or cloud MQTT broker.
Modbus RTU to MQTT
For serial/RS-485 equipment, vNode connects over Modbus RTU using the port, baud rate, parity, stop bits and slave ID configured for each device, so legacy serial Modbus data can participate in the same MQTT architecture — through the same gateway.
Registers to MQTT Topics
Modbus organizes data into coils, discrete inputs, input registers and holding registers. vNode maps each raw address to a named tag — e.g. holding register 40001 becomes Line1.Temperature — published under a topic such as factory/line1/temperature.
Reliable Modbus to MQTT with Store&Forward
What happens if the MQTT broker, WAN or cloud connection goes down? vNode continues polling Modbus devices locally and stores the acquired data with full timestamps. Once connectivity is restored, the buffered data is automatically forwarded — separating plant-floor collection from temporary northbound communication failures.
Modbus TCP/RTU
Read Modbus data
MQTT connection interrupted
Automatic Resume
No data loss
Built-in local buffering
Automatic resume
Sends pending data when connection is restored
Reliable delivery
Handles intermittent connectivity
Simple configuration
No custom code required
Secure MQTT Delivery
TLS Encryption
Encrypt the connection between vNode and the MQTT broker.
Digital Certificates
Authenticate the gateway and the broker with certificate-based security.
Authentication
Control access to the MQTT broker with standard user authentication.
Connect Modbus Data to Cloud and IT Systems
The same Modbus data can reach on-premise or cloud MQTT infrastructure, historians, MES and analytics platforms.
Generic Broker
Any standard MQTT broker
Mosquitto
Open-source MQTT broker
HiveMQ / EMQX
Enterprise MQTT broker
AWS IoT
Cloud IoT platform
Azure IoT Hub
Cloud IoT platform
Beyond Modbus to MQTT
The same vNode deployment can combine Modbus with additional OT sources and enterprise destinations.
More OT Sources
More Destinations
MQTT, OPC UA, SQL, REST, cloud platforms, historians and enterprise applications.
Operational Scale
Unlimited tags/connections, Windows/Linux/ARM deployment and industrial resilience features.
Related vNode Modules to Build This Architecture
Connect Modbus Devices to MQTT
Use vNode to bridge industrial Modbus data with modern MQTT and cloud architectures.
Frequently Asked Questions
What is a Modbus to MQTT gateway?
It is software that reads data from Modbus devices and publishes that information to MQTT topics so IT, cloud and analytics applications can consume it.
Can vNode connect Modbus TCP to MQTT?
Yes. vNode’s Modbus Client supports Modbus TCP and the platform can deliver collected data to MQTT destinations.
Can vNode connect Modbus RTU / RS-485 to MQTT?
Yes. vNode supports Modbus RTU acquisition as well as MQTT data delivery, allowing serial Modbus data to participate in modern MQTT architectures.
How are Modbus registers mapped to MQTT topics?
Each Modbus coil, discrete input or register is mapped to a named vNode tag, which is then published under a configurable MQTT topic — for example, holding register 40001 can become the tag Line1.Temperature and the topic factory/line1/temperature.
Can Modbus data be published as structured MQTT payloads?
Yes, vNode can structure multiple Modbus tags into a single JSON payload per MQTT message, rather than publishing only raw, unstructured values.
What happens if the MQTT broker or network is unavailable?
vNode Store&Forward is designed to buffer undelivered data locally and forward it after communication is restored.
Can Modbus data be sent to AWS or Azure using MQTT?
Yes, Modbus data collected by vNode can be published to MQTT brokers and cloud services including AWS IoT and Azure IoT Hub.
Do I need to write code to connect Modbus to MQTT?
The standard Modbus-to-MQTT path is configured through vNode rather than requiring a custom protocol bridge application.
Can one vNode instance collect from multiple Modbus devices?
Yes, a single vNode instance can poll multiple Modbus TCP and Modbus RTU devices and publish their data to MQTT through one gateway.
Can vNode combine Modbus with OPC UA, Siemens or Rockwell data in the same architecture?
Yes, vNode supports 40+ industrial protocols in the same platform, so Modbus can be combined with OPC UA, Siemens S7, Rockwell EtherNet/IP and others feeding the same MQTT destinations.