Overview
The HD-S90 (nine-element sensor) and HD-S70 (seven-element sensor) are environmental monitoring devices developed by Shenzhen Huidu Technology Co., Ltd.
They are intended for outdoor or semi-outdoor use such as LED display setups, digital signage, or other monitoring installations where environmental data is important.
Features & What They Measure
Here’s a breakdown of what they do (especially what distinguishes them):
Feature HD-S90 HD-S70 Comments
Wind speed & direction (ultrasonic) — S90 has wind sensors; S70 lacks these two metrics.
Temperature & Humidity Both measure ambient temperature & humidity.
Atmospheric Pressure Range up to ~120 kPa.
Particulate Matter (PM2.5/PM10) 0-1000 µg/m³, resolution ~1 µg/m³, with dual-frequency collection and auto calibration.
Noise Level ~30-120 dB range.
Light Intensity (Lux) Very wide range, up to ~200,000 Lux. Sensitivity probe; good resolution.
Technical & Physical Specs
Power input: 10-30 V DC.
Power consumption: HD-S90 ≈ 1.2 W when using RS-485 output.
Communication: RS-485 (Modbus-RTU). Supports long cable runs up to ≈ 2000 meters under proper wiring.
Accuracy & Ranges:
Wind speed: 0-60 m/s; accuracy ±(0.2 m/s + 0.02×v) where v = measured speed.
Wind direction: 0-359°; ±3°
Temperature: approx ±0.5 °C at 25 °C.
Humidity: ± 3% RH around 60% RH at 25 °C.
Atmospheric pressure: ±0.15 kPa at 25 °C in certain ranges.
PM2.5 / PM10: ±10% (at 25 °C)
Noise: ±3 dB
Light intensity: ±7% at 25 °C for typical range.
Durability & Construction:
Made of UV-resistant materials. Weatherproof.
High-sensitivity probes, imported components for enhanced stability.
Long-term stability: For example temperature drift ≤ 0.1 °C/year; humidity drift ≤ 1% RH/year; pressure drift etc.
Use Cases & Installation Notes
These sensors are suitable for LED display system monitoring (outdoor signage, large screens, control rooms) where environmental conditions like wind, dust (PM), temperature, humidity etc. might affect operation.
The HD-S90 is ideal when wind measurement is also needed (for example, to protect displays or ensure safety in high wind).
Both sensors can be used in networked setups, sending data via RS-485 to PLCs, controllers or monitoring software.
The devices support secondary development (custom software integration) via their RS-485 / Modbus registers.
For installation, the S90 has an ultrasonic wind sensor (so orientation / mounting matters somewhat), but it also has a built-in electronic compass in some models to reduce orientation errors. Horizontal mounting required.
