MQTT

In modern industrial environments, the need for fast, lightweight, and reliable data exchange is growing. In this article, we explain what MQTT for IIoT means, why it is useful for IIoT integrations, and what steps you should take to prepare a production or field environment for MQTT messages. The explanation is practical and intended for both technicians and management and documentation teams.

MQTT for IIoT: Brief Overview

MQTT is an open, lightweight publish/subscribe protocol that runs on top of TCP/IP. It is designed for telemetry in networks with limited bandwidth and high reliability requirements. Thanks to the publish/subscribe model, you send messages to a central broker, and other systems subscribe to relevant topics. This creates a flexible layer between OT systems and cloud or IT systems.

What is MQTT

MQTT works via a broker: devices publish messages, and subscriptions lead to delivery to interested recipients. This is especially useful if there are many devices, network bandwidth is limited, or your systems are distributed or cloud-based. MQTT supports features such as quality levels for delivery (QoS), topic structures, and security via TLS.

Key Features

Important properties you should know:

1. Lightweight protocol: minimal overhead, ideal for embedded devices.
2. Publish/Subscribe architecture: scalable through central broker.
3. Asynchronous communication: devices do not always have to be online.
4. Security: TLS encryption and authentication via username/password or certificates.
5. Topic structure: hierarchical topics such as factory/line1/temperature.
6. Quality of Service (QoS): QoS 0, QoS 1, and QoS 2 for delivery guarantees.

Supported Devices and Applications

MQTT is widely used in both industrial and commercial environments. Typical examples include PLCs, edge gateways, sensors, and cloud platforms. Modern PLCs can publish MQTT messages via extra modules or gateways; in many cases, a gateway helps to connect older systems without native MQTT connectivity. The first mention of PLCs is often linked to solutions for secure connections and data logging for legacy systems: see PLCs and legacy support.

Practical Integrations and Examples

Many installations use a gateway or router layer to translate traditional protocols (e.g., S7) to MQTT. Well-known gateways and hardware variants (ServiceGate modules) are often used to connect legacy systems without native MQTT: an example is the ServiceGate family. For management and access to endpoints, you can use tools such as a remote access infrastructure or a remote portal for overview and connections.

Setting up an Environment for MQTT

Follow these basic steps to use MQTT reliably and securely:

1. Install or use an MQTT broker: popular brokers are Mosquitto, EMQX, and HiveMQ CE. Choose local or in the cloud.
2. Configure network and security: MQTT uses standard port 1883 (unsecured) and 8883 (TLS). Activate TLS, certificates, and strong authentication to mitigate risks. Cybersecurity remains a top priority here.
3. Determine topics and message structure: use clear, hierarchical topic names such as production/line1/status.
4. Configure devices: set up PLCs, gateways, or edge controllers to publish or subscribe to topics.
5. Integration with existing systems: run MQTT in parallel with traditional protocols; use gateways for protocol conversion.

Quality, Security, and Reliability

Ensure that your QoS settings match the impact of lost messages. Use TLS and certificates for encryption, and consider network segmentation and VPNs for extra security. For operational management and access, a combination of secure remote access tooling and logging platforms is often used; this allows you to audit and analyze connections and data flows.

What to Consider During Implementation

Practical considerations:

1. Define clear topic conventions and retention policies.
2. Limit message size and frequency on low-bandwidth links.
3. Use broker-high-availability and monitoring for production environments.
4. Link device management to your security and patch policy; security and cybersecurity must be included from the design phase.
5. Make use of available management apps and integrations such as the remote-connect-control-app for management and connections.

Conclusion

Thanks to its lightweight protocol, publish/subscribe model, and broad support by devices and platforms, MQTT is very suitable for IIoT integrations between OT and IT/cloud. With a correct broker, clear topic structure, security via TLS, and good device management, you can deploy MQTT safely and scalably. In many projects, gateways (e.g., ServiceGate modules) and smart controllers form the bridge between traditional PLC systems and modern cloud platforms, and solutions for remote access and portals are used to streamline management and logging. For practical examples and products, you can also visit the provider pages and solution pages of Remote.