Leveraging the Potential of MQTT in Industry 4.0

Summary

In this article, Sparkplug and OPC UA are compared as MQTT-based solutions according to the requirements of the Industry 4.0 scenarios Plug & Work and Condition Monitoring. While it can be reasonable to use Sparkplug, if a system’s configuration does not change too often and if a binary encoding is what is needed, OPC UA being a well-established international standard, has a lot to offer, e.g. regarding cybersecurity and scalable (re-) configuration based on semantic information models.
 
Interoperability and scalability are key requirements for the implementation of Industrie 4.0 (I4.0) application scenarios targeting flexible and resilient production systems. In place of the rigid structures and heterogeneous communication solutions used in Operational Technology (OT) today, loosely coupled systems using standardized interfaces and information models are needed in order to decrease the high manual effort for (re-)configuration.

With this regard, the Publish-Subscribe (PubSub) communication paradigm is well suited for the implementation of loosely coupled systems, that can e.g. be implemented using the MQTT application protocol. However, MQTT is data agnostic and does not address interoperability on the information layer, i.e. the definition of topic trees and payloads are up to the user. Specifications like Sparkplug B (Sparkplug) and the standard OPC Unified Architecture (OPC UA) use MQTT as a transport protocol and add such missing features.
 
Nevertheless, for end users it might be hard to identify distinguishing features and choose between different MQTT based solutions. In this article, Sparkplug and OPC UA are compared according to the following requirements of the I4.0 scenarios Plug & Work and Condition Monitoring:

1. Uniform Interface
2. Standardized Semantic Information Models
3. Scalability
4. Low Bandwidth
5. Cybersecurity
6. International Standard
7. Adoption
8. Compliance & Certification

 You can find the entire analysis in this full paper as a free download.