Modbus and DALI sensors are designed for different roles in building automation and lighting control. Modbus is a flexible, general‑purpose protocol widely used for industrial and building automation, while DALI is a specialized protocol created specifically for digital lighting control. A clear understanding of how these protocols differ in architecture, data handling, and typical applications is essential for selecting the right Andivi sensors and system design for your project.
Below you will find an overview of both protocols, their key functional differences, main advantages, and typical use cases, along with short answers to frequently asked questions.
Overview of Modbus Protocol
Modbus is an open communication protocol widely used in building management systems (BMS) and industrial automation for real‑time monitoring and control. It connects sensors, meters, I/O modules and controllers via simple read/write operations on registers, which store values such as temperature, humidity, CO₂, energy and status bits.
Most Andivi devices use Modbus RTU over RS‑485, with some systems also using Modbus TCP over Ethernet, giving flexibility for both smaller local networks and large sites. Andivi Modbus sensors are available as temperature, humidity, CO₂/air‑quality and differential pressure versions, and can be used indoors, outdoors, in ducts or on surfaces, all on the same bus line.
Because Modbus is so widely supported, Andivi Modbus sensors can be integrated into almost any modern PLC, SCADA or BMS without vendor lock‑in, making them a universal choice for HVAC, energy and process data acquisition.
Overview of DALI Protocol
DALI – Digital Addressable Lighting Interface – is a dedicated protocol for digital lighting control, standardised in IEC 62386 and further refined in DALI‑2. A DALI line is a 2‑wire, low‑speed bus with its own power supply, used to connect luminaires, LED drivers, presence and light sensors, and wall‑mounted control devices in professional lighting systems.
Each DALI network supports individually addressable devices and groups, enabling precise control of single luminaires, zones and scenes with simple commands (for example set group brightness, recall scene, query lamp failure). Presence and lux sensors on the DALI bus feed directly into the lighting logic, enabling occupancy‑based and daylight‑dependent dimming without complex external wiring.
Typically, DALI is used as the internal lighting subsystem, while integration with HVAC, energy monitoring or other protocols (like Modbus or BACnet) happens via gateways or multi‑protocol controllers.
Key Functional Differences
Modbus and DALI both use digital communication, but they differ strongly in data focus, architecture and network design.
Data and purpose
Modbus sensors expose numeric measurements and status in registers: temperature (°C), humidity (%), CO₂ (ppm), differential pressure, energy counters and digital I/O. DALI devices exchange lighting‑specific commands such as brightness levels, scenes, group control, occupancy flags and lux values for constant light control.Architecture and communication model
Modbus usually follows a master–slave / client–server pattern: a BMS or PLC polls Andivi Modbus sensors over RS‑485 or Ethernet, reading and writing registers cyclically. DALI uses a DALI controller and multi‑device bus, where commands between controller, luminaires and sensors are exchanged on the same line, and multiple control devices can exist on one network.Wiring and scale
Modbus RTU can support long distances and many devices on a single RS‑485 segment, and Modbus TCP scales over existing Ethernet infrastructure, making it suitable as a building‑wide backbone. DALI is limited to a defined number of devices and cable length per line, which fits floor or zone‑level lighting circuits but not general plant‑wide communication.
In practice, Modbus is chosen when broad, multi‑discipline automation is needed, while DALI is chosen when fine‑grained lighting control is the main objective.
Advantages of Each Protocol
Advantages of Modbus Sensors (Andivi)
Multi‑purpose sensing on one bus
Andivi Modbus sensors cover temperature, humidity, CO₂/air quality and differential pressure, so one Modbus line can collect most key HVAC and energy‑related data points in a building.Easy integration with BMS and PLCs
Modbus is supported by almost all building controllers and SCADA systems, which makes Andivi Modbus sensors easy to integrate into new and existing installations using a standard, well‑documented protocol.Flexible installation options
Andivi offers Modbus sensors for indoor rooms, outdoor areas, ducts, ceilings, surface mounting and even special applications such as radiation or enthalpy measurement, giving designers consistent communication while choosing the right mechanical form factor.
Advantages of DALI Sensors and Devices
Precise, addressable lighting control
DALI supports individual and group addressing with standardized dimming and scene functions, enabling high‑quality, comfortable and energy‑efficient lighting in offices, schools, hospitals and retail.Optimized for lighting wiring
A single 2‑wire DALI bus carries both control signals and bus power for electronics, reducing the amount of separate control wiring needed for switches, sensors and luminaires in a lighting circuit.Standardized ecosystem
DALI‑2 and related specifications define the behavior of control gear and control devices (including sensors), improving interoperability between different manufacturers within the lighting system.
Ideal Use Cases and Applications
Choose Modbus sensors when your project centres on HVAC, indoor climate, and energy monitoring. Andivi Modbus sensors can measure room and duct temperature, humidity, CO₂, and differential pressure, and send these values directly to AHUs, room controllers, and the central BMS over a shared RS‑485 bus.
Modbus is also ideal for combining HVAC data with energy meters and industrial devices (boilers, chillers, pumps, drives), so the PLC or BMS can optimize overall performance and energy usage using one unified protocol.
Choose DALI when the primary focus is professional, addressable lighting control. DALI presence and light sensors, together with DALI drivers and control panels, handle occupancy‑based switching, daylight‑dependent dimming, and lighting scenes on a room, zone, or floor level.
DALI is particularly attractive in new lighting installations or major refurbishments, where a dedicated lighting bus simplifies control and commissioning while still allowing integration with higher‑level systems via gateways (for exampl,e to share occupancy information with an HVAC system using Modbus).
Frequently Asked Questions
Can Modbus and DALI Work Together in the Same System?
Yes. Modbus is typically used for HVAC, metering, and plant control, while DALI is used for lighting; both can run in parallel and be linked through a central controller or gateway that exchanges key data such as occupancy and energy usage between the two systems.
Are There Cost Differences Between Modbus and DALI Sensors?
Modbus sensors, such as Andivi Modbus temperature or CO₂ sensors, are usually very cost‑effective when many measurement points share the same RS‑485 or Ethernet infrastructure. DALI sensors can be economical in lighting‑only projects because they use the DALI bus, but they require DALI‑compliant drivers, power supplies and controllers, so Modbus often offers a better price‑performance ratio in mixed HVAC and energy applications.
How Do Environmental Factors Affect Modbus and DALI Performance?
For Modbus, long cables, interference and poor RS‑485 termination can reduce communication quality, so good cabling, shielding and grounding are important. DALI is optimized for shorter lighting circuits, where correct cable length, proper power supply sizing and respecting device limits per line are the main conditions for reliable operation.
Are There Any Compatibility Issues With Existing Devices?
Yes, if devices are not configured or implemented correctly. Modbus devices, including Andivi Modbus sensors, must use the correct function codes and register maps in the PLC or BMS, while DALI and DALI‑2 devices must follow the standard and be properly commissioned; checking documentation and testing communication during startup helps avoid problems.
What Security Measures Are Available for Modbus and DALI?
Classic Modbus and DALI have limited built‑in cybersecurity, so protection is usually implemented at network level: segmentation, secure gateways, firewalls and encrypted remote access for IP‑based parts of the system. For DALI, physical access control and securing any gateways to higher‑level networks are the key practical security measures.
