Context card
What a connectivity server does between an AI system and a machine
What does an industrial connectivity server or integration platform do between an AI system and a machine?
The short answer
An industrial connectivity server collects data from controllers and devices through protocol-specific drivers, normalizes it, and offers it through standardized interfaces such as OPC UA and MQTT; an integration platform additionally routes and transforms data flows toward IT systems. For an AI system this layer is the defined handover point: it supplies stable read access and turns a released action into one addressable write or method call. It is not an AI component and it does not decide whether an action is permitted — configured permissions and the plant's own safeguards do.
For: Automation engineers and technical writers documenting OT/IT integration
Key points
- Connectivity servers hide controller-specific protocols behind one normalized access point.
- MQTT carries messages; OPC UA adds an addressable information model with services, states and methods.
- AI sits above this layer: it interprets data and proposes actions, it does not transport them.
- Whether a write or method call is accepted depends on configured client and write permissions, not on the AI output.
- Logging and uniform addressing make it traceable which client read or wrote which value.
The context
Three layers, one handover point
Industrial architectures that use AI results separate transport, structure and interpretation. MQTT forms the message- and event-oriented level: clients publish to topics on a broker and subscribers receive states and events, and can send defined messages back. OPC UA forms the structured industrial level: data points, states, events, released write accesses and method calls become addressable in an information model, and companion specifications define domain-specific models maintained by the OPC Foundation. The AI layer sits above both. It classifies states, detects anomalies or produces an option — it does not move data.
Between field level and these interfaces sits the connectivity server. It uses device-specific drivers for PLCs, machines and legacy OPC interfaces, normalizes tags and data types, and publishes them once for many clients. PTC's Kepware Server is an example of this function; inray's OPC Router is an example of an integration layer that additionally routes between OPC UA, MQTT, SQL, SAP and REST. Naming them here is descriptive, not an endorsement.
What this layer decides and what it does not
The value of the layer for AI operations is limitation, not freedom. An AI output can remain a recommendation, an MQTT message or a defined OPC UA call. Whether it becomes an intervention depends on client, user, group and write permissions configured in the server: vendor documentation for Kepware Server, for example, describes project settings for OPC UA client access, including whether clients may write and how method calls relate to I/O write permissions (as of September 2026). Configuring such settings does not make a system safe or compliant; interlocks, limit values, safe states, approvals and human intervention remain part of the plant concept.
What to document
Document which tags and methods are exposed to which client identity, which AI function may trigger which call, the release step between proposal and execution, and where the log entry for a write is kept. A stable interface must not hide a change behind it: if the underlying controller, address or permission model changes, the documented handover point changes too.
Questions readers ask next
- Is a connectivity server an AI component?
- No. It is communication and integration software. It transports, normalizes and mediates data; interpretation and proposal generation happen in the AI layer above it.
- Why not let the AI talk to the controller directly?
- Direct access would require the AI to handle every controller dialect and would spread credentials and write rights across systems. A single normalized access point concentrates permissions, logging and addressing.
- What is the difference between a connectivity server and an integration platform?
- A connectivity server focuses on device drivers and standardized interfaces for many clients. An integration platform focuses on routing and transforming data flows between OT and IT systems. Products often combine both roles.
Sources
- Project Properties — OPC UA — PTC Support (Kepware Server Help), September 29, 2026
- How to configure client access permissions and security in Kepware Server — PTC, September 29, 2026
- OPC Router: Automate IT/OT data flows — inray Industriesoftware, September 29, 2026
- UA Companion Specifications — OPC Foundation, September 29, 2026
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