Choosing Between MQTT and OPC UA for Smart Automation and Manufacturing

Effective smart automation and manufacturing begin with collecting and analyzing sensor data to uncover valuable insights, including identifying patterns, trends, and anomalies. Two widely used industrial transmission protocols that stand out are Message Queuing Telemetry Transport (MQTT) and Open Platform Communications Unified Architecture (OPC UA). In this post, I’ll compare their key features to help you choose the best option for your application.

MQTT is a lightweight messaging protocol built for high efficiency and low bandwidth usage when transmitting data between devices. It uses a publish-subscribe model, where clients send messages to a center broker, and subscribers receive only the messages relevant to them. This model enables scalability with minimal overhead, making MQTT ideal for large-scale deployments. The raw data is transmitted in lightweight formats such as JavaScript Object Notation (JSON), plain text, or binary, which makes MQTT efficient for simple telemetry and event-driven data exchange. 

Introduced in 2006, OPC UA was designed to enable secure data exchange and seamless interoperability across industrial devices, applications, and enterprise systems. It supports both a client-server and a publish-subscribe communication model. In the client-server model, clients can request data, write values, or subscribe to updates, while servers store and provide data from sensors, machines. or other systems. OPC UA organizes information in a hierarchical structure of objects and variables, making it easier to navigate, maintain context, and enable real-time, deterministic data exchange between machines. 

Feature comparison: MQTT vs. OPC UA

The choice between MQTT and OPC UA depends on the specific needs of your application. MQTT, with its lightweight design and low bandwidth requirements, is ideal for cloud-centric use cases. It transmits raw data without needing a structured model, making it easy to integrate with big data platforms, analytics tools, and AI systems. Thanks to its broker-based architecture, MQTT can scale efficiently to support thousands or even millions of devices. In contrast, OPC UA is built for secure, machine-to-machine communication on the factory floor. Its hierarchical data models and rich semantic information enable interoperability across different PLCs, SCADA, MES, and ERP systems. By understanding the strengths of each protocol, you can select the one that best fits your needs and optimize your smart manufacturing and automation systems.