IIoT and machine connectivity glossary.

IIoT

Industrial Internet of Things · FR: IIoT, internet industriel des objets

The Industrial Internet of Things is the network of sensors, controllers and machines in industry that send data to other systems. It is the industrial branch of the Internet of Things, the wider network of connected devices.

What separates it from consumer IoT is the cost of being wrong: a machine stopped by a network problem or a value read incorrectly has consequences on output and safety. That is why industrial protocols such as OPC UA and MQTT focus on reliable delivery, structured data and security.

PLC

Programmable Logic Controller · FR: automate programmable

A programmable logic controller is the industrial computer that runs a machine: it reads its inputs, executes the control program in a fast cycle and drives its outputs. It is the most common source of machine data.

Its program was written to run the machine, not to report on it, so the values a production system needs (a cycle count, a state, an alarm) may not exist as clean variables. Reading data from a controller often starts with agreeing which variables to expose, and how.

Sensor

FR: capteur

A sensor converts a physical quantity into a signal: presence, position, temperature, pressure, vibration, flow. It is the first link between a physical process and any system that records it.

Most production data comes from sensors through the machine’s controller rather than directly. Adding a sensor to equipment that has none is often the simplest way to count cycles or detect a state on an old machine, with the signal brought in through a gateway.

SCADA

Supervisory Control and Data Acquisition

SCADA is software that supervises and controls processes across many machines or a whole site: it collects values from controllers, displays them, raises alarms and lets operators issue commands.

It sits at ISA-95 level 2, focused on the process as it runs. An MES sits above it and works in terms of orders, products and people rather than tags and alarms; on many sites the two coexist, and the MES reads some of its data through the same connections.

HMI

Human-Machine Interface · FR: IHM

A human-machine interface is the screen or panel through which an operator monitors and controls a machine or process. It can be a panel on the machine itself or a station supervising several.

A machine HMI shows the machine’s own world: its states, alarms and settings. An MES operator terminal shows the production world: the order, the counts, the reason for the stop. Putting both on one screen is possible; keeping them distinct in purpose avoids confusion on the line.

OPC UA

OPC Unified Architecture

OPC UA is an open, platform-independent standard for exchanging industrial data securely, with information models that describe what each value means as well as its value. It is the successor to the original Windows-based OPC.

Many recent controllers include an OPC UA server, so a production system can browse and subscribe to their variables directly. Its information models are its strength and its cost: richer than a raw register, and more work to set up well. VZIAM MES reads OPC UA natively.

MQTT

Message Queuing Telemetry Transport

MQTT is a lightweight messaging protocol in which devices publish messages to named topics on a broker and other systems subscribe to the topics they need. It was designed for unreliable networks and small devices.

The broker decouples the sender from the receivers, so a new consumer can be added without touching the machine. MQTT defines the transport, not the meaning of the payload, so a plant using it has to agree topic names and message formats. VZIAM MES reads MQTT natively.

Publish and subscribe

Pub/sub · FR: publication et abonnement

Publish and subscribe is a messaging pattern in which senders publish messages to a topic without knowing who will receive them, and receivers subscribe to the topics they want. A broker in between delivers each message to every subscriber.

Its opposite is polling, where a client asks each device for its values in turn. Pub/sub sends values when they change, which suits events such as a stop or a count; polling suits devices that cannot publish. Many plants use both.

HTTP push

Webhook

HTTP push is a device or system sending data to a receiving server by HTTP request whenever there is something to report, rather than waiting to be asked. A webhook is the same idea between software applications.

It uses the most widely supported protocol there is, so data boxes, gateways and scripts can all send it. It suits events and periodic summaries; for high-frequency values from many machines a broker is usually more efficient. VZIAM MES accepts HTTP push natively.

Modbus

Modbus RTU, Modbus TCP

Modbus is a simple, long-established protocol for reading and writing registers in industrial devices, over a serial line (RTU) or Ethernet (TCP). Many controllers, meters and drives support it.

Its registers are numbers without names, so using its data means knowing from the device documentation what each address holds. It is polled rather than event-driven. VZIAM MES connects to Modbus devices through a gateway that translates their registers into MQTT or HTTP.

Siemens S7

S7 protocol

S7 is the communication protocol of Siemens SIMATIC S7 controllers, used to read and write their data blocks over Ethernet. It is proprietary, though widely supported by third-party drivers.

Recent S7 controllers also offer an OPC UA server, which is usually the cleaner route for a production system. For older ones, a gateway reads the S7 data and passes it on. VZIAM MES connects to S7 controllers through such a gateway.

Protocol gateway

Data acquisition box, edge gateway · FR: passerelle

A protocol gateway is a device or piece of software that reads data in one protocol and passes it on in another, such as from Modbus registers or a proprietary controller to MQTT. It is how equipment that cannot speak a modern protocol joins a connected system.

Node-RED and dedicated data acquisition boxes are common gateways. Each one is a configuration that has to be kept, so the mapping from each register to each named value is worth documenting. VZIAM MES uses gateways for Modbus, S7 and proprietary controllers.

Tag

Data point, variable · FR: variable

A tag is a named data point in an industrial system: one value, such as a temperature, a state or a counter, with its name, type and source address. Controllers, SCADA systems and historians are organised in tags.

Tag names are where most integration time goes: the same quantity is called something different on every machine, by every integrator, in every year. A naming convention agreed before connecting machines saves more effort than any later mapping tool.

Data historian

Process historian · FR: historien de données

A data historian is a database built to store the values of many tags over time, efficiently and in order, and to retrieve them by tag and time range. It is the long-term memory of a process.

It records what the values were, not what they meant: a historian knows a counter rose, but not which order was running or why the machine stopped. An MES adds that context, and many plants keep both, the historian for the process and the MES for production.

Time-series data

FR: série temporelle

Time-series data is a sequence of values recorded with their timestamps, such as a machine’s state, speed or temperature over a shift. Most machine data has this shape.

Its quality depends on the timestamps as much as the values: clocks that drift between machines make it impossible to tell which stop came first. Storing state changes rather than sampled values keeps the record exact and compact for production questions.

Edge computing

FR: informatique en périphérie

Edge computing processes data close to where it is produced, on or near the machines, rather than sending everything to a central server or a cloud. It reduces latency and the volume of data that has to travel.

In a plant the edge is often a gateway or an industrial PC beside the line, doing protocol translation, filtering or simple calculations. Where the central system itself runs on the plant network, much of what is sold as edge computing is already local.

Unified namespace

UNS

A unified namespace is an architecture in which every system publishes its current data to one shared, hierarchically named structure, usually on an MQTT broker, and every other system reads from it. The hierarchy typically follows the plant: site, area, line, machine.

It replaces point-to-point interfaces with one place to publish and subscribe. Its success depends almost entirely on the naming hierarchy and on discipline in keeping to it, which is an organisational decision more than a technical one.