SCADA glossary

A configured condition that requires operator awareness or action, often with priority, acknowledgement, shelving, and event history.

Related: Deadband, HMI

A threshold range used to suppress insignificant changes, prevent alarm chatter, or reduce historian noise.

Related: Alarm, Historian

A time-series database and service layer for storing industrial process values, events, alarms, batches, and production context over time.

Related: Trend, Tag

Human-Machine Interface: screens operators use to view equipment state, issue commands, acknowledge alarms, and understand process behavior.

Related: SCADA, Alarm, Trend

Manufacturing Execution System: software layer that manages production execution, work orders, quality, traceability, recipes, and performance context.

Related: Recipe, Historian

Serial Modbus protocol commonly used over RS-485, where devices are addressed by unit ID and data is exchanged as compact binary frames.

Related: Register, Polling

Ethernet variant of Modbus that reads and writes coils and registers using TCP/IP, often on port 502.

Related: Register, Polling

Lightweight publish/subscribe messaging protocol commonly used for IIoT telemetry, edge gateways, and cloud-connected industrial systems.

Related: OPC UA, Polling

OPC Unified Architecture: platform-independent industrial interoperability standard with typed address spaces, subscriptions, security, and services.

Related: MQTT, SCADA

Programmable Logic Controller: rugged industrial controller that reads inputs, executes logic, and writes outputs for machines or processes.

Related: Tag, Register

A communication pattern where a client repeatedly requests data from a device or server at a configured interval.

Related: Deadband, Modbus TCP

A managed set of production parameters, setpoints, limits, or steps used to run a product, batch, or machine mode consistently.

Related: Setpoint, MES

A numbered data location in a device protocol such as Modbus, often represented as coils, discrete inputs, input registers, or holding registers.

Related: Modbus TCP, Tag

Supervisory Control and Data Acquisition: software and infrastructure used to monitor, visualize, alarm, historize, and sometimes control industrial processes.

Related: HMI, PLC, Historian

A target value entered by an operator, recipe, or control system for a controller or process variable to follow.

Related: Recipe, Tag

A named data point in an HMI/SCADA system, usually mapped to a controller address, calculation, alarm source, or historian point.

Related: Setpoint, Deadband

A visual plot of process values over time, used for operations, troubleshooting, and engineering analysis.

Related: Historian, Tag