Air Lite Modbus Air Quality Sensor

The Sensorbee Air Lite Modbus is a compact air quality sensor designed for direct integration with industrial control systems. Using the industry-standard Modbus RTU protocol over RS-485, the Air Lite Modbus connects to PLCs, SCADA platforms, building management systems, and data loggers without requiring cloud connectivity or cellular networks. Built-in sensors for particulate matter (PM0.5, PM1, PM2.5, PM10), temperature, humidity, and noise deliver multi-parameter environmental data through a single 0.3 kg device.

How It Works

The Air Lite Modbus measures environmental parameters using the same sensor suite as the Air Lite Cellular — optical particle counting across four size fractions, onboard temperature and humidity sensing, and an optional noise meter. The difference is in data delivery: instead of transmitting over cellular networks, the Air Lite Modbus communicates via RS-485 using the Modbus RTU protocol. A master device (PLC, SCADA controller, or data logger) polls the Air Lite Modbus at its configured address and reads measurement registers directly. This approach integrates environmental monitoring into existing industrial automation infrastructure without requiring internet connectivity, cloud subscriptions, or SIM cards.

The unit accepts 5–35 VDC input — a wider voltage range than the cellular variant — making it compatible with standard industrial 12V and 24V power supplies commonly found in control panels and junction boxes.

Integration With Industrial Systems

The Air Lite Modbus is built for straightforward integration into existing automation architectures:

• Modbus RTU over RS-485 — standard two-wire communication compatible with virtually any industrial controller, PLC, or SCADA system manufactured in the last three decades
• Configurable slave address — set the Modbus address via the USB configuration port to avoid bus conflicts when multiple devices share the same RS-485 network
• Internal termination switch — an onboard bus termination resistor can be enabled or disabled via a physical switch, eliminating the need for external termination resistors at the end of the RS-485 bus
• USB configuration port — configure device parameters, update firmware, and run diagnostics without disconnecting from the Modbus bus
• Standard register map — measurement data is available in standard Modbus holding registers, with documentation provided for straightforward integration into any HMI or SCADA polling configuration

Built-In Sensors

Every Air Lite Modbus includes four measurement capabilities:

• Optical Particle Counter — PM0.5, PM1, PM2.5, and PM10 measurement across four size fractions, providing more granular particulate data than the cellular variant
• Temperature Sensor — -40 to +60°C range with ±1°C accuracy
• Humidity Sensor — 0–100% RH with ±5% RH accuracy
• Noise Meter — 20 Hz to 10 kHz frequency range, 40–100 dBA with ±4 dBA accuracy

All sensors share a two-year operational life with field-replaceable service.

Why Choose the Modbus Variant

The Air Lite Modbus addresses a specific requirement that cellular-connected monitors cannot: direct integration with on-premises industrial control systems where data must remain on the local network.

• No cloud dependency — environmental data stays on your local network, read directly by your existing SCADA or BMS. Ideal for facilities with strict data governance policies or limited internet connectivity
• No recurring SIM costs — Modbus RTU communication eliminates cellular data charges, reducing the total cost of ownership for permanent installations
• Wide voltage input — the 5–35 VDC range accepts power from standard 12V and 24V industrial supplies, control panel auxiliary outputs, and DIN rail power supplies without additional voltage conversion
• PM0.5 measurement — the Modbus variant includes PM0.5 measurement (particles ≥0.5 µm) in addition to PM1, PM2.5, and PM10, providing an additional ultrafine particle size fraction
• Drop-in installation — the same 150 × 80 × 55 mm housing and 0.3 kg weight as the cellular variant, but with RS-485 wiring instead of a SIM card

Deployment and Installation

The Air Lite Modbus installs like any RS-485 field device. Connect the two-wire RS-485 bus, apply 5–35 VDC power, and configure the Modbus slave address via the USB port. The internal termination switch simplifies bus topology — enable termination on the last device in the chain and disable it on all others.

For multi-point installations, daisy-chain multiple Air Lite Modbus units on a single RS-485 bus with unique addresses. Each unit is polled independently by the master device, and all measurement registers are documented in the integration guide supplied with each unit.

Mount the compact housing on poles, walls, or within protective enclosures using standard brackets. The polycarbonate and polyamide construction withstands outdoor exposure across the -20 to +60°C operating range.

Applications

• Building management systems — integrate indoor and outdoor air quality data directly into BMS platforms for HVAC control, occupant comfort management, and ventilation optimisation without cloud middleware
• Industrial facility monitoring — connect to existing SCADA systems for continuous environmental monitoring at manufacturing plants, warehouses, and processing facilities where Modbus RTU is the standard communication protocol
• Tunnel and underground monitoring — particulate matter and environmental data delivered via hardwired RS-485 in environments where cellular connectivity is unavailable or unreliable
• Clean room and controlled environments — PM0.5 measurement capability supports monitoring in environments where ultrafine particle counts are critical to process quality
• Data logger integration — connect to standalone data loggers at remote sites where neither cellular nor internet connectivity is practical
• Retrofit installations — add air quality monitoring to existing industrial control networks without new communication infrastructure, cloud subscriptions, or IT network changes

Frequently Asked Questions

How does this differ from the Air Lite Cellular?

The Air Lite Modbus replaces cellular connectivity with RS-485 Modbus RTU, enabling direct integration with PLCs, SCADA systems, and data loggers. It also adds PM0.5 measurement, accepts a wider 5–35 VDC input range, and does not require a SIM card or cloud subscription.

Can I use it with the Sensorbee Cloud?

The Air Lite Modbus does not connect directly to the Sensorbee Cloud. However, you can route Modbus data to the cloud through a gateway or edge controller that translates Modbus registers to LwM2M or another cloud protocol.

How many units can share one RS-485 bus?

A standard RS-485 bus supports up to 32 devices without repeaters. Each Air Lite Modbus is assigned a unique slave address via the USB configuration port.

Does the noise meter require a separate licence?

Yes, the noise meter hardware is built in but requires a software licence for activation, the same as the cellular variant. The licence can be applied via the USB configuration port.

What Modbus registers are available?

Each measurement parameter (PM0.5, PM1, PM2.5, PM10, temperature, humidity, noise level) is mapped to standard Modbus holding registers. The complete register map is included in the integration documentation supplied with the unit.