Industry 4.0 technologies are usually summarised as nine pillars, from the Industrial Internet of Things and cloud computing to simulation, autonomous robots and augmented reality. In this explainer you will learn what each pillar actually means on a plant floor, what it needs to work, and why a shared messaging layer such as MQTT is the thread that turns nine separate technologies into one connected system.
Where the Nine Pillars Come From
The term Industry 4.0 originated in Germany in the early 2010s as a name for the fourth industrial revolution: the combination of physical production with digital information and networking. The nine-pillar grouping became popular through consulting and industry publications as a practical way to explain what that combination involves. It is not a formal standard, and other frameworks group the technologies differently, but the nine pillars are a useful map.
What the lists often miss is that the pillars are not independent purchases. A simulation is only as good as the live data feeding it. Analytics need data from machines. Augmented reality is useful when it shows the current state of the equipment in front of you. Almost every pillar depends on the same thing: reliable, structured, real-time data from production. That is why our Industry 4.0 guide treats connectivity as the first step.
The 9 Industry 4.0 Technologies at a Glance
| Pillar | What it does | Data it needs | Role of MQTT |
|---|---|---|---|
| 1. Industrial IoT | Connects machines, sensors and devices | Raw signals from the floor | Primary transport from edge to broker |
| 2. Big data and analytics | Finds patterns, predicts failures, optimises | Historical and live process data | Feeds historians and analytics pipelines |
| 3. Cloud computing | Provides elastic compute and storage | Data from many sites | Outbound, firewall-friendly path to the cloud |
| 4. Horizontal and vertical integration | Links machines, MES, ERP and suppliers | Shared context across systems | Unified Namespace as the shared hub |
| 5. Simulation and digital twins | Models processes and assets virtually | Live state and history | Live feed that keeps the twin current |
| 6. Autonomous robots | Performs tasks with little supervision | Commands, positions, status | Status and fleet coordination messages |
| 7. Cybersecurity | Protects connected systems | Identity, logs, network design | TLS, authentication, outbound-only design |
| 8. Additive manufacturing | Builds parts layer by layer | Job data, machine status | Printer status and job tracking |
| 9. Augmented reality | Overlays information on the physical world | Current asset state, instructions | Live values pushed to headsets and tablets |
The Pillars Explained
1. Industrial Internet of Things
IIoT is the foundation layer: PLCs, sensors and controllers connected so their data can leave the machine. In practice that means gateways that read PLC tags or sensor values and publish them over a lightweight protocol. MQTT dominates this role because it is small, event-driven and works through firewalls with outbound connections only. If the publish/subscribe model is new to you, start with what an MQTT broker does.
2. Big data and analytics
Once data flows, analytics can turn it into decisions: overall equipment effectiveness, energy per part, early warning of bearing failure. Today this pillar increasingly includes machine learning. The quality of the result depends far more on clean, contextualised data than on the algorithm, so topic naming and payload design matter as much as the model.
3. Cloud computing
Cloud platforms provide storage and compute that scale across many sites without buying servers for each plant. They also make it practical to compare sites against each other. The design challenge is getting data out of segmented OT networks safely, which is where outbound-only MQTT connections to a cloud MQTT broker fit well.
4. Horizontal and vertical system integration
Vertical integration links the shop floor to MES and ERP. Horizontal integration links the plant to suppliers, logistics and customers. Historically, both were built with point-to-point interfaces. The modern approach is a Unified Namespace: one event-driven hub where every system publishes what it knows and subscribes to what it needs, organised by the ISA-95 hierarchy.
5. Simulation and digital twins
Simulation lets engineers test a layout, a schedule or a control strategy before touching real equipment. A digital twin goes further by staying synchronised with the physical asset through live data. Our digital twin technology guide explains the different levels of twin, from a 3D visual model to a full physics simulation.
6. Autonomous robots
Industrial robots have existed for decades. Industry 4.0 robots are more flexible, more collaborative and more connected: mobile robots navigate the plant, cobots work beside people, and fleets report status centrally. Safety-critical motion control stays on dedicated controllers and fieldbuses, while MQTT typically carries status, job assignments and telemetry to supervisory systems.
7. Cybersecurity
Connecting everything increases the attack surface. This pillar covers network segmentation, identity, encryption, monitoring and patching across both IT and OT. For messaging specifically, the essentials are TLS on every connection that leaves a zone, per-device credentials and a design that never requires inbound ports into the plant. See our MQTT security best practices for details.
8. Additive manufacturing
3D printing in metal and polymers enables complex geometries, spare parts on demand and short runs without tooling. From a connectivity standpoint, printers are machines like any other: their job status, build progress, chamber temperatures and alarms belong in the same namespace as the rest of the plant.
9. Augmented reality
AR overlays information onto what a technician sees: work instructions, live sensor values, maintenance history. It is only as useful as the data behind it. A headset that shows yesterday's temperature is worse than none. Live data pushed by MQTT over secure WebSocket is a natural fit for browser-based and mobile AR applications.
How MQTT Connects the Industry 4.0 Technologies
Look at the table again and a pattern appears: every pillar either produces or consumes live production data. Without a shared layer, each pairing becomes its own integration, which grows painfully as you add technologies. With an MQTT broker in the middle, each technology connects once.
Here is what a single message in a well-designed namespace might look like. One retained message on connectmq/acme/plant1/machining/line2/cnc07/telemetry:
{
"ts": "2026-10-16T08:30:00Z",
"state": "RUNNING",
"spindleSpeed": 8200,
"spindleLoad": 61.5,
"partCount": 1342,
"program": "O4512",
"coolantTemp": 24.8
}
The same message serves several pillars at once. The analytics pipeline stores it for trend analysis. The digital twin updates the 3D model's state. The AR tablet shows spindle load to the technician standing at the machine. The MES updates the part count against the work order. None of these consumers needed a new interface to the machine. You can see the publish/subscribe pattern live in a minute:
mosquitto_sub -h broker.connectmq.com -p 1883 -i i40-demo-$RANDOM \
-t 'connectmq/demo/i40-7f3a/#' -v &
mosquitto_pub -h broker.connectmq.com -p 1883 -i i40-pub-$RANDOM -r \
-t connectmq/demo/i40-7f3a/plant1/line2/cnc07/telemetry \
-m '{"state":"RUNNING","spindleLoad":61.5,"partCount":1342}'
Where to Start
Trying to adopt all nine pillars at once is a reliable way to get none of them working. A pragmatic order for most manufacturers:
- Connect a small set of critical machines (pillar 1) with a secure design (pillar 7).
- Put their data into a structured namespace that other systems can use (pillar 4).
- Add analytics and dashboards on top (pillar 2), in the cloud where it makes sense (pillar 3).
- Add simulation, AR, robotics and additive projects as business cases appear, reusing the same data layer.
Our IIoT architecture reference shows how these layers fit together technically. If you are also wondering how the newer Industry 5.0 agenda changes these priorities, read Industry 5.0 vs Industry 4.0.
The Messaging Layer, Managed
The data layer is the one piece every other pillar depends on, so it needs to be secure, available and easy to observe. ConnectMQ is a hosted MQTT broker supporting MQTT 3.1.1 and 5.0 over TLS and secure WebSocket. It detects ISA-95 and Unified Namespace topics, decodes Sparkplug B and republishes it into readable ISA-95 topics, and its portal includes a live topic explorer and threshold alerts. ConnectMQ also offers a 3D digital twin web demo of a factory with CNC, robot arm, furnace, tank, conveyor and pump, all driven live over secure WebSocket, which is a practical illustration of pillars 1, 4 and 5 working together.
Get Started with ConnectMQ
Create a free Serverless broker at app.connectmq.com, no credit card required. Connect one machine, give it a clean ISA-95 topic, and you have the foundation every other Industry 4.0 technology can build on.
Frequently Asked Questions
What are the 9 pillars of Industry 4.0?
Industrial IoT, big data and analytics, cloud computing, horizontal and vertical system integration, simulation, autonomous robots, cybersecurity, additive manufacturing and augmented reality.
Which Industry 4.0 technology should a factory adopt first?
Usually Industrial IoT connectivity with a secure design, because analytics, digital twins and AR all depend on live machine data being available.
Where does MQTT fit in Industry 4.0?
MQTT is the messaging layer that moves data from machines to every other technology. Its publish/subscribe model lets analytics, twins, MES and AR consume the same data without separate integrations.
Is AI one of the Industry 4.0 pillars?
Not in the original nine, but machine learning is now commonly treated as part of big data and analytics. It relies on the same connected, well-structured production data.
