Industry 4.0 — OT/IT convergence

Industry 4.0, stripped of the marketing, is the problem of getting plant-floor data into enterprise systems in a form those systems can act on. The hard part is almost never transport (networks and brokers are a solved problem); it is semantics: what a value means, which machine and which batch it belongs to, and whether two machines from different builders describe the same event the same way. AEI Corporation works on that layer: OPC UA and DDS integration, machine-to-MES interfaces, edge gateways and the cloud path above them.

Any of a dozen protocols will move a temperature reading from a machine to a server. None of them tell the server that the reading is a barrel-zone temperature, that it belongs to injection cycle 4,812, that the cycle belongs to a production order, or that “cycle complete” on this machine means what it means on the one beside it.

That gap is what re-appears as integration cost. It is the reason two projects with identical network diagrams differ by an order of magnitude in effort, and the reason information models — OPC UA's address space, its companion specifications, DDS topic types — are the real engineering surface. A project that spends its design time on the model and its implementation time on the transport tends to finish; the reverse tends not to.

The reference frame is ISA-95 (standardised as IEC 62264), which layers production from the control level up through manufacturing operations (MES) to business planning (ERP), and defines what information legitimately crosses each boundary. It is worth using even informally: most “our MES needs a direct tag subscription from the PLC” requests are boundary violations that later become maintenance problems.

• OPC UA (IEC 62541) — the interoperability layer at the boundary: a typed address space, standardised security, client/server and pub/sub, and companion specifications that give an industry a shared vocabulary. This is what MES and SCADA generally consume.
• DDS — the data-centric publish/subscribe backbone inside a distributed system: high-rate, peer-to-peer, with fine-grained QoS. Complementary to OPC UA far more often than competing with it.
• Cloud and IIoT — what belongs above the plant at all, and the store-and-forward, identity and cost questions that come with sending it there.
• Edge gateways — where brownfield reality lives: serial, I2C and fieldbus devices aggregated and given a modern interface without replacing the machine.

Below all of this sits the deterministic layer: industrial real-time Ethernet and fieldbus, a different engineering problem with different constraints, which should not be designed as if it were part of the IT network.

We design and implement the interface between those two worlds: OPC UA servers and information models on machines, companion-specification implementations (PackML, EUROMAP and others), DDS backbones and their QoS design, machine-to-MES connectivity, and the edge gateway work underneath, including brownfield equipment that predates all of it. The common thread is that we work on both sides of the boundary, which is usually where the failures actually are.

• IEC 62264 (ISA-95) — enterprise-control system integration; the layer model and the information crossing each boundary
• IEC 62541 — OPC Unified Architecture, the multi-part specification series
• OMG DDS — the Data Distribution Service specification family, including the DDSI-RTPS wire protocol
• ISA-88 / PackML — batch control and packaging machine state models (see the companion-specification page)

• Technology namespace
• Industrial real-time Ethernet — the deterministic layer below
• MQTT — the messaging alternative, and where it does and does not fit
• AEI Corporation — system integration