AMP-RHT485
Industrial RS485 Modbus Temperature & Humidity SensorA compact, fully calibrated temperature, humidity and dew-point probe that plugs straight into any RS485 Modbus network. Built around a Sensirion SHT4x sensor, it delivers precise, stable readings for HVAC, buildings, cleanrooms, warehouses and industrial panels — with up to 32 sensors on a single cable run.
- High accuracy: ±0.2 °C and ±2% RH at 25 °C, with full-range temperature compensation
- Long-term stable, low drift: < ±0.25% RH per year; reliable in high humidity
- Standard Modbus RTU over RS485, up to 1,200 m and 32 devices per bus
- Ultra-low power: ≤ 1 mA typical from a 5–24 V DC supply
Precise climate data on your Modbus network
The AMP-RHT485 is a networked temperature and humidity sensor with an RS485 interface and the standard Modbus RTU protocol, so it connects directly to PLCs, SCADA, building management systems and data loggers without any converter or gateway.
Its sensing element, the Sensirion SHT4x, combines an improved capacitive humidity element with a band-gap temperature sensor on a single CMOSens chip. It is fully calibrated and temperature-compensated across the whole humidity range, giving accurate, consistent readings and better stability in high-humidity conditions than earlier sensor generations.
Alongside temperature and relative humidity, the sensor calculates dew point — the key value for spotting condensation risk in panels, cold rooms and storage areas. Several sensors can share one RS485 cable, each with its own Modbus address.
| General | |
|---|---|
| Model number | AMP-RHT485 |
| Sensing element | Sensirion SHT4x digital temperature & humidity sensor, fully calibrated |
| Measured values | Temperature, relative humidity, dew point |
| Mounting | Wall bracket, 2 × Ø3.5 mm holes at 29 mm centres |
| Housing | PC+ABS, black |
| Temperature | |
| Measuring range | -40 °C to +120 °C (recommended use -40 to +85 °C) |
| Accuracy | ±0.2 °C (at 25 °C) |
| Resolution | 0.1 °C (0.01 °C on request) |
| Humidity | |
| Measuring range | 0–100% RH |
| Accuracy | ±2% RH / ±3% RH (at 25 °C) |
| Resolution | 0.1% RH (0.01% RH on request) |
| Hysteresis | < ±0.8% RH |
| Response time | Approx. 8 s (33–75% RH, moving air) |
| Long-term stability | < ±0.25% RH per year (clean environment) |
| Dew point | |
| Measuring range | -60 °C to +80 °C |
| Accuracy | ±2 °C |
| Resolution | 0.1 °C (0.01 °C on request) |
| Communication | |
| Interface | RS485, Modbus RTU (function code 03) |
| Baud rate | 4800 / 9600 / 19200 bps, default 9600 8-N-1 |
| Bus length | Up to approx. 1,200 m (depends on cable and baud rate) |
| Devices per bus | Up to 32 |
| Power & environment | |
| Supply voltage | 5–24 V DC |
| Current consumption | ≤ 1 mA typical, 1.5 mA max |
| Operating environment | -40 °C to +85 °C, 0–100% RH (non-condensing) |
| Storage environment | -40 °C to +85 °C, 0–100% RH (non-condensing) |
| Mechanical | |
| Probe dimensions | Ø14 × 110 ±5 mm |
| Connection | 4-core cable: red V+, black GND, yellow A+, green B− |
Default 9600 bps, 8 data bits, no parity, 1 stop bit (9600-8-N-1). Baud rate 4800 / 9600 / 19200 and Modbus address can be preset at order or changed with a Modbus tool (write single register, function 06).
Read holding registers with function code 03. Example request for address 1, two registers: 01 03 00 00 00 02 C4 0B. Values are returned as integers × 10.
| 0x0000 (0) | Temperature · °C × 10 (signed) Example: 00FA → 250 → 25.0 °C |
|---|---|
| 0x0001 (1) | Relative humidity · % RH × 10 Example: 0258 → 600 → 60.0% RH |
| 0x0002 (2) | Dew point · °C × 10 (signed) Example: 00FA → 250 → 25.0 °C |
Lab-grade accuracy, industrial connectivity
Every sensor is factory calibrated with temperature compensation over the full humidity range.
Long-term stability better than ±0.25% RH per year means fewer recalibrations.
Standard RTU protocol and RS485 wiring — no gateway needed for PLC, SCADA or BMS.
Protected RS485 interface for stable communication on long, multi-drop cable runs.
Complete your monitoring system
Battery-powered wireless version for panels where running cable isn’t practical.
View product
Need accurate climate monitoring?
Tell us how many points you need and how they connect to your system, and we’ll preset addresses and baud rates before delivery.
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