BAS & IoT Glossary
This glossary covers core terminology in Building Automation Systems (BAS), Internet of Things (IoT), and energy management, organized by category for quick reference.
A — Automation & Control
| AI (Analog Input) | Receives continuously variable physical signals (temperature, pressure, flow), typically 0-10V or 4-20mA |
| AO (Analog Output) | Outputs continuous control signals, e.g., valve position or VFD frequency |
| API | Application Programming Interface — protocols for software system interaction, e.g., RESTful API for data upload |
B — Building Automation
| BACnet | Building Automation and Control Networks — ANSI/ASHRAE 135 standard protocol designed for building automation |
| BAS | Building Automation System — integrated system for automatic monitoring and control of building mechanical/electrical equipment |
| BIM | Building Information Modeling — digital 3D model covering full building lifecycle, can integrate real-time sensor data |
C — Communication
| CAN | Controller Area Network — high-reliability serial protocol widely used in automotive and industrial control |
| CO₂ Sensor | Carbon dioxide sensor — monitors CO₂ concentration, commonly using NDIR technology |
| Current Transformer | Converts large current to proportional small current for energy monitoring |
D — Digital & Data
| DDC | Direct Digital Control — closed-loop control system centered on digital computers, foundation of BAS |
| DI (Digital Input) | Receives binary status signals (on/off, run/stop, alarm/normal) |
| DO (Digital Output) | Outputs binary control signals for equipment start/stop, valve open/close |
| Digital Twin | Virtual mapping of physical systems with real-time synchronization, used for simulation and optimization |
E — Energy Management
| EMS | Energy Management System — software platform for real-time monitoring, analysis, and optimization of building energy consumption |
| Enthalpy | Total heat content of air (sensible + latent), used for HVAC fresh air energy-saving control |
H — HVAC
| HVAC | Heating, Ventilation and Air Conditioning — collective term for building climate control systems |
I — IoT
| IoT | Internet of Things — network connecting objects and people through information sensors |
| IP Rating | e.g., IP65 = dust-tight and water jet resistant; IP67 = temporary immersion capable |
M — Communication Protocols
| Modbus | Serial communication protocol (RTU for serial, TCP for Ethernet), most widely used in industrial applications |
| MQTT | Lightweight publish/subscribe protocol designed for low-bandwidth IoT devices |
| MS/TP | BACnet serial communication sub-protocol over RS-485 bus |
N — Network
| NDIR | Non-Dispersive Infrared — core detection technology for CO₂ sensors, high accuracy and stability |
O — Open Standards
| OPC UA | Open Platform Communications Unified Architecture — secure data exchange standard for industrial automation with semantic modeling |
P — Sensors & Control
| PM2.5 | Fine particulate matter ≤2.5μm aerodynamic diameter, affecting air quality and health |
| PID Control | Proportional-Integral-Derivative — most common closed-loop control algorithm for precise regulation |
| PT100/PT1000 | Platinum resistance temperature sensors — high accuracy and stability |
R — Communication Interface
| RS-232 | Serial interface standard — point-to-point, max 15m, being replaced by RS-485 |
| RS-485 | Differential serial standard — 32 nodes, 1200m range, physical foundation of field buses |
| RTU | Remote Terminal Unit — remote data acquisition and control device, common in SCADA |
S — Systems
| SCADA | Supervisory Control and Data Acquisition — centralized monitoring platform for large facilities |
| Sensor | Device converting physical quantities to electrical signals, foundation of IoT perception |
T — Transmission
| TCP/IP | Transmission Control Protocol / Internet Protocol — foundational Internet protocol suite |
| Transmitter | Converts sensor signals to standard industrial signals (0-10V / 4-20mA) |
V — Variable & Measurement
| VFD | Variable Frequency Drive — adjusts motor speed for energy savings, key for fan/pump efficiency |
| VOC | Volatile Organic Compound — indoor air pollutant affecting health and comfort |
Z — Wireless
| Zigbee | Low-power wireless Mesh protocol based on IEEE 802.15.4, ideal for sensor networks |
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