MQTT Simply Explained
MQTT (Message Queuing Telemetry Transport) is a lightweight, event-driven protocol that operates on a publish/subscribe architecture, making it an efficient alternative to the conventional client-server model.
Clients in an MQTT network, such as buttons, temperature sensors or touch panels, publish or subscribe to messages under specific topics. A broker (server) ensures seamless communication and secure data exchange as a central entity.
Thanks to its compact message format and event-based communication, which does not require continuous data transmission, MQTT uses minimal bandwidth and memory. This makes MQTT ideal for use in resource-constrained IoT applications.
Key Terms and Functions at a Glance
Any device with an MQTT library can be integrated into the network as an MQTT client. Depending on the function, the clients behave differently: sensors only publish their status (publish), while smartphones usually act as subscribers, displaying the current status of loads or building segments. Room control units or controllers also serve as clients, capable of subscribing to and publishing messages, thus functioning in a controlling manner within the MQTT network.
The MQTT Broker
Communication in an MQTT network occurs via the MQTT broker, which is an edge device or server that organizes and coordinates the messages and communication of MQTT clients. The broker serves as the central manager and distributor of messages between end devices. Unlike traditional client/server architectures, devices in an MQTT network do not communicate directly with one another.
News and Topics
MQTT messages are sent from clients to the broker and require very little memory – one of the protocol’s strengths. In addition to the data (payload), the topic is also published. The broker filters the messages by topics and forwards them to all subscribed clients.
Topics can be organized hierarchically in MQTT and structured with forward slashes (/). For instance, a temperature sensor in a conference room could publish a message under the topic BuildingA/Meeting1/Temperature.
Three different Quality of Service (QoS) levels allow network designers to choose between minimum data transmission and maximum reliability. At the lowest level (QoS 0), each message is sent exactly once, without confirmation. In the middle stage (QoS 1), a message is sent multiple times until a receipt confirmation is received, ensuring it arrives at least once. QoS 2 is the most reliable level but also the most complex and resource-intensive. Here, the message arrives at the broker only once, leading to higher CPU usage and lower battery life for battery-operated devices.
How MQTT Works with WAGO
The following components and solutions ensure the success of your IoT project – whether in buildings or other industries.
WAGO I/O System 750
Whether inside or outside the control cabinet, WAGO’s I/O systems provide automation exactly where you need it – even under harsh conditions.
WAGO PFC200 Controller
Our PFC200 Series Controllers offer a variety of functions, making them ideal for building automation applications. The PFC200 (Generation 2) supports MQTT connections from the outset.
WAGO Compact Controller 100
With its DIN-rail-mount enclosure and integrated I/Os, the Compact Controller 100 needs minimal control cabinet space. This compact solution enables you to address automation tasks tailored to your specific environment.
WAGO Edge Controller
The WAGO Edge Controller features a quad-core ARM Cortex-A9 processor and offers a wide range of interfaces. Its extensive functionalities make it ideal for customized applications across various industries.
WAGO Touch Panel 600
WAGO's Touch Panels (HMI – Human Machine Interface) enhance the operability of machines and systems, showcasing impressive design and technology. The Touch Panel 600 supports MQTT connections right from the start.
Multi-Cloud Connectivity – Single License
“Multi-Cloud Connectivity” enables the simultaneous connections of a device to two different cloud systems, IoT platforms or MQTT brokers, allowing tasks to be performed in the most suitable cloud application.
Sparkplug Software – Single License
Sparkplug is an MQTT-based specification designed for IoT applications. It defines the topic and payload formats, enabling controllers to exchange data directly with Sparkplug-compatible systems, such as SCADA.
WAGO Application Solutions and MQTT
Pre-Programmed Solutions for Greater Simplicity
WAGO offers pre-programmed applications for room automation, lighting, energy data management and load management in charging parks. These applications require no programming, simplifying your tasks. WAGO Application Solutions utilizes MQTT in various ways; for example, pre-programmed applications in combination with MQTT are useful for connecting to third-party systems. This facilitates effective data transmission to higher-level systems, such as Building Management Systems (BMS) or the cloud. Learn more about WAGO’s application solutions on our website.
