SCADA & Automation Glossary
Essential terms and definitions for industrial automation professionals.
Showing 48 of 48 terms
A
Alarm Management—System for detecting, notifying, and managing abnormal process conditions. See ISA-18.2.
Analog Input (AI)—Continuous signal (0–10V, 4–20mA) representing a process variable like temperature or pressure.
B
Batch Control—Automated control of batch manufacturing processes. See ISA-88/S88.
BACnet—Building Automation and Control Networks protocol for HVAC and building systems.
C
CIP (Common Industrial Protocol)—Application layer protocol used by Ethernet/IP and DeviceNet.
Cold Standby—Redundancy mode where the backup server starts only when the primary fails.
CFR 21 Part 11—FDA regulation for electronic records and signatures in regulated industries.
D
DCS (Distributed Control System)—Control system with autonomous controllers distributed throughout the plant. More integrated than SCADA.
Deadband—Range of values within which a change does not trigger an alarm or historian sample.
Digital Twin—Virtual replica of a physical process for simulation and analysis.
E
Ethernet/IP—Industrial Ethernet protocol by ODVA, used primarily with Allen-Bradley PLCs.
E-Signature—Electronic signature compliant with 21 CFR Part 11 for audit trails.
F
Faceplate—Pop-up display showing detailed information about a single tag or device.
Fieldbus—Family of industrial network protocols for real-time distributed control (e.g., PROFIBUS, Foundation Fieldbus).
G
GAMP5—Good Automated Manufacturing Practice guide for validation of computerized systems in pharma.
Gateway—Device that bridges communication between different industrial protocols or networks.
H
Historian—Database optimized for storing time-series process data with compression.
HMI (Human-Machine Interface)—Operator interface for monitoring and controlling industrial processes. Often part of a SCADA system.
Hot Standby—Redundancy mode where the backup server runs in parallel and takes over instantly.
I
IIoT (Industrial Internet of Things)—Network of connected industrial devices sharing data for monitoring and optimization.
ISA-18.2—Standard for alarm management in process industries. Covers alarm lifecycle, rationalization, and performance metrics.
ISA-88 (S88)—Standard for batch control systems. Defines procedure hierarchy: procedure → unit procedure → operation → phase.
ISA-95—Standard defining the integration between enterprise (IT) and control (OT) systems.
L
Ladder Logic—Graphical PLC programming language resembling electrical relay diagrams. One of the IEC 61131-3 languages.
M
MES (Manufacturing Execution System)—Software that tracks and manages manufacturing operations between ERP and the shop floor.
Modbus—Serial/Ethernet communication protocol. Variants: Modbus RTU (serial), Modbus TCP (Ethernet). Simple register-based read/write.
MQTT—Lightweight publish-subscribe messaging protocol for IIoT applications.
O
OEE (Overall Equipment Effectiveness)—Performance metric: Availability × Performance × Quality. Target: 85%+.
OPC UA—Open Platform Communications Unified Architecture. Modern, secure, cross-platform industrial communication standard.
OT (Operational Technology)—Hardware and software for monitoring and controlling physical processes. Distinct from IT.
P
PID Controller—Proportional-Integral-Derivative controller. Feedback loop mechanism for maintaining a process variable at a setpoint.
PLC (Programmable Logic Controller)—Industrial computer for real-time control of machinery and processes.
PROFINET—Industrial Ethernet standard by Siemens for communication between controllers, I/O, and drives.
Purdue Model—Reference architecture for industrial network segmentation (Levels 0–5).
PWA (Progressive Web App)—Web application that works offline and can be installed on mobile devices like a native app.
R
RBAC (Role-Based Access Control)—Security model where permissions are assigned to roles, not individual users.
Redundancy—Duplicate systems (hot/cold standby) to ensure high availability.
RTU (Remote Terminal Unit)—Field device that collects data from sensors and sends it to a SCADA master station.
S
S7 Protocol—Siemens proprietary protocol for direct communication with S7-300/400/1200/1500 PLCs.
SCADA—Supervisory Control and Data Acquisition. System for monitoring and controlling industrial processes from a central location.
SFC (Sequential Function Chart)—Graphical programming method for sequential/batch processes. Used in ISA-88.
SOE (Sequence of Events)—High-resolution (1ms) recording of events for incident investigation.
SPC (Statistical Process Control)—Use of statistical methods to monitor and control a process, ensuring it operates at its full potential.
T
Tag—Named data point in a SCADA system representing a process variable (temperature, pressure, flow, etc.).
TLS/SSL—Transport Layer Security. Encryption protocol for secure communication between SCADA clients and servers.
V
VFD (Variable Frequency Drive)—Device that controls motor speed by varying the frequency of the electrical power supplied.
W
WAL (Write-Ahead Logging)—Database technique where changes are written to a log before the database, ensuring data integrity.
WebSocket—Full-duplex communication protocol enabling real-time data updates between server and browser.
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