KNOWLEDGE CENTER
OPC UA, OPC DA, DCOM, MQTT, Sparkplug B, Kepware and more: short, accurate definitions of the terms used in industrial data integration.
The network of nodes (objects, variables, methods) and references that an OPC UA server exposes to clients.
A client browses the address space to discover what data exists. A well-designed address space reflects the equipment hierarchy instead of a flat tag list.
The MQTT server that distributes messages from publishers to subscribers.
The broker manages connected clients, subscriptions and retained messages. In production, redundant deployment and authentication are part of the design.
An existing, operating plant full of installed equipment and systems; the opposite of a newly built (greenfield) plant.
In brownfield plants the aim is to get data out without touching the running PLC program; drivers and gateways make this possible.
Read moreAn additional specification that standardizes the OPC UA information model for a specific industry or machine type.
For example, a shared model lets machine builders make different machines readable in the same way, which lowers integration cost.
Microsoft’s distributed COM technology; the machine-to-machine transport of classic OPC.
DCOM is complex to configure, hard to troubleshoot and unfriendly to firewalls. Microsoft’s DCOM hardening updates of recent years can cause connection problems in older OPC DA installations.
Read moreA digital model of a physical asset or process, fed with real data.
A digital twin depends on a reliable real-time data flow; the OPC UA information model provides a suitable basis for building it.
Read moreAn intermediate security zone between IT and OT networks that prevents direct two-way access.
Data-collection servers and brokers are often placed in this zone; the OT side only makes outbound connections.
The component that speaks the communication protocol of a device family and translates the data to a standard interface.
Separate drivers exist for protocols such as Modbus, Siemens S7 and EtherNet/IP. Choosing a driver starts from the device and the protocol it speaks.
Read moreA computer or device running close to the field that collects, pre-processes, buffers and forwards data to upper systems.
The edge gateway forms the boundary between legacy devices and the cloud or UNS; protocol translation and buffering happen here.
The combination of an OPC UA server’s address with the security mode and policy it offers.
A server can offer several endpoints (for example insecure for testing and signed-and-encrypted for production). The client selects the endpoint during connection.
Enterprise resource planning: the system that manages purchasing, inventory, finance and production planning.
Data flow between the ERP and the shop floor is usually built through an MES or an integration layer.
A time-series database that stores process data with timestamps efficiently and makes it queryable.
A historian keeps history for trends, reports and analysis. The timestamp and quality of every record determine how trustworthy it is.
The series of standards for the cybersecurity of industrial automation and control systems.
It defines the zone and conduit concepts and is the reference for network segmentation and access design.
Industrial Internet of Things: field devices sharing data with networks and cloud services.
The success of IIoT projects usually depends on first building solid data acquisition at the field.
Read moreThe structure of types, units and relationships that defines what data means; where OPC UA departs from flat tag lists.
With an information model, a “Pump” is defined as an object whose speed, current and state are its properties. The same model can be reused across devices from different vendors.
The international standard that divides integration between enterprise systems (ERP) and manufacturing systems into levels and roles (IEC 62264).
ISA-95 defines the field (levels 0–2), MES (level 3) and ERP (level 4) layers. It is the starting point for the naming hierarchy in architectures such as the UNS.
The industrial connectivity platform that connects to hundreds of devices and protocols through drivers and serves the data as OPC UA and OPC DA (formerly KEPServerEX).
In Kepware Server, configuration follows a channel, device and tag hierarchy. It brings PLCs from many vendors under one standard interface and bridges legacy systems and new applications.
Read moreManufacturing execution system: manages production orders, recipes, traceability and production results.
The MES is the layer between the ERP and the shop floor. It works with real-time data from PLCs and therefore depends on a reliable data acquisition layer.
Read moreA simple and widespread serial/Ethernet communication protocol developed in 1979.
Modbus TCP uses port 502 by default. Thanks to its simplicity it is still very common in meters, drives and analysers.
Read moreA lightweight publisher–subscriber messaging protocol designed for low bandwidth and unreliable networks.
In MQTT, data is published to topics through a broker and distributed to subscribers. It has three quality-of-service levels: at most once (0), at least once (1) and exactly once (2). Standard ports are 1883 (plain) and 8883 (TLS).
Read moreOverall equipment effectiveness: availability × performance × quality.
OEE calculation relies on accurate state information, counters and standardized downtime codes, which makes data collection critical.
Read moreThe classic COM/DCOM-based OPC Data Access interface; it runs only on Windows.
OPC DA has been one of the most widespread OPC interfaces in the field since the 1990s. Because it relies on DCOM for security and remote access, migration to OPC UA comes onto the agenda as network segmentation and security requirements grow.
Read moreThe non-profit organization that develops OPC specifications and runs their certification.
The foundation also coordinates the development of companion specifications alongside OPC UA.
Read moreIntegration software that lets you configure data movement between systems visually with triggers, mapping and transformation rules.
OPC Router connects endpoints such as PLCs, OPC UA servers, SQL databases, MES/ERP and MQTT. Because it works in both read and write directions, it suits two-way scenarios such as order and recipe transfer.
Read moreCarrying classic OPC (DA) traffic over OPC UA so that DCOM is removed between machines.
It is a practical way to give an old DA client or server a secure, firewall-friendly connection without changing it, and serves as an interim step in a migration.
Read moreThe platform-independent industrial interoperability standard with certificate-based security and a rich information model (IEC 62541).
OPC UA presents data not only as values but together with type, unit and relationships. The default port is 4840, and signing and encryption are supported. It is not tied to Windows and is preferred over OPC DA for new projects.
Read moreOPC UA’s publisher–subscriber model; it delivers data to many subscribers without sessions, over UDP multicast or MQTT/AMQP.
PubSub complements the client–server model for scenarios with many consumers or low-latency needs. Client–server is still used for commands and queries.
Read moreHardware and software that directly monitors and controls the production process; it has different availability and safety priorities than IT.
In IT/OT integration the OT network is kept in separate zones, and data is shared through controlled gateways (DMZ).
Read moreProgrammable logic controller: a controller that reads field inputs and drives outputs in a repeating scan cycle.
PLC data is reached with vendor-specific protocols; drivers hide this difference and present one standard interface.
Read moreThe status code that indicates a data point’s reliability: Good, Uncertain or Bad.
In OPC UA, quality is expressed in the severity bits of the status code. Reports must not present a bad-quality value as if it were a normal one.
Read moreSupervisory software that collects data from controllers, shows it to operators, records it and sends commands.
SCADA and HMI applications usually get their data from OPC servers, so the quality of the OPC connection shows directly in operator screens.
The Eclipse Foundation specification that adds a topic namespace, payload format and device lifecycle rules on top of MQTT.
Sparkplug B uses BIRTH and DEATH messages to announce when a device comes online or goes offline, so subscribers know whether data is current or stale. It aims to make products from different vendors interoperate.
Read moreStoring data locally when the target is unreachable and forwarding it in order once the connection returns.
Buffer size is chosen for the longest expected outage, and identifiers and timestamps are used to prevent duplicate records.
Read moreThe name given to an addressable data point in a device; it carries value, type and access properties.
Tag names should be unique and meaningful within the driver and device hierarchy, because reports, alarms and integrations bind to them.
Information showing when data was produced or received; OPC UA keeps source and server timestamps separate.
The difference between the two reveals latency and stale data. Timestamps cannot be trusted without clock synchronization (NTP).
Read moreThe list of certificates an OPC UA application trusts; it must be populated on both sides before a connection can be made.
Most servers place an unknown client certificate in a “rejected” list and wait for an administrator’s approval. The connection drops when a certificate expires, so renewal is an operational task.
Read moreAn architectural approach in which all systems publish and read data in one hierarchical namespace, usually on an MQTT broker.
A UNS is a rule rather than a product: an ISA-95-style hierarchy from enterprise to cell is reflected in the topic name and becomes the single source of truth for current state. It aims to reduce the number of point-to-point integrations.
Read moreNo matching terms.
