What is MQTT Sparkplug?

Since its launch in 1999, MQTT (Message Queuing Telemetry Transport) has been a valuable standards-based messaging protocol for automation applications. Its lightweight, efficient “publish-subscribe” model makes it ideal for communication between and across various devices, systems, and services. MQTT has transformed applications in supply chain management, quality control, predictive maintenance, M2M communication, and industrial energy management.

Designed for general-purpose messaging between low-constraint devices, MQTT has remained vendor-neutral. However, certain drawbacks have limited its widespread adoption in manufacturing and industrial automation. For example, the devices used and data communicated in these industries are rarely always inter-operational, often using different formats or protocols.

The diversity of devices, data formats, and transmission protocols makes device-to-device communication using MQTT cumbersome. Each device would require individual configuration to subscribe to specific topics and interpret the received data.

This led Arlen Nipper, the original developer of MQTT, to create a similar protocol to MQTT — one’s that’s reliable, scalable, and efficient. Meet MQTT Sparkplug, a protocol designed to meet the industry-specific needs in the manufacturing sector.

What is MQTT Sparkplug?

MQTT Sparkplug is an M2M messaging protocol based on MQTT but designed for the Industrial Internet-of-Things (IIoT). This protocol adds features to the existing MQTT standard, making it more suitable for applications in the manufacturing sector.

For instance, Sparkplug:

Introduces MQTT topic namespaces, which provide a structured way to organize data within MQTT topics.
Offers state management, which effectively implements mechanisms for managing device states and data updates.
Provides a standardized format for encoding and decoding data into MQTT payloads.

Thanks to these features, different devices or software platforms can easily be discovered by other network components. Sparkplug adds context to the MQTT data, making it more interpretable between devices. This means previously incompatible devices or applications from different equipment manufacturers and software providers now have a way to exchange data and integrate it into a standard network.

The protocol also ensures a single source of truth, creating a unified view of the data across an entire network. All data over the MQTT Sparkplug is communicated with TLS encryption to ensure high-quality security. (Note: to use Sparkplug, an MQTT broker must implement the MQTT version 3.1.1.)

Sparkplug is implemented by MQTT brokers, allowing non-interoperable devices in a manufacturing setup to communicate effectively without engineering overhead. The MQTT Sparkplug is a valuable tool for building reliable and scalable IIoT applications. Due to its industry-tailored design, the protocol is widely used in industrial automation, smart manufacturing, energy management, and supply chain management.

MQTT versus MQTT Sparkplug

Plain MQTT and MQTT Sparkplug are extremely different. As mentioned, the MQTT Sparkplug was developed on top of the MQTT standard. Here are a few of their differences:

While MQTT is confined to general-purpose messaging between devices over a low-bandwidth network, Sparkplug is specifically tailored for the IIoT.
While MQTT supports a flexible user-defined topic structure, Sparkplug has a standardized topic namespace.
While MQTT supports no predefined data format, Sparkplug has a defined data model and payload structure.
While MQTT has no built-in platform for discovering data sources, Sparkplug provides mechanisms for finding new data sources within the network.
While adding context to the data in MQTT is impossible, Sparkplug makes it possible to transform data into more interpretable assets.

Plain MQTT is the foundation on which Sparkplug was built to add more structure and capabilities. Essentially, Sparkplug has transformed the protocol into a practical and efficient solution for the IIoT. It’s made it possible to integrate incompatible devices into a standard industrial communication network.