# XY-MD02 Modbus temperature and humidity sensor: specs

> A temperature and humidity module that carries a Sensirion SHT20 sensor and talks Modbus RTU over RS-485. Only the SHT20 sensor is documented here.

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A temperature and humidity module that carries a Sensirion SHT20 sensor and talks Modbus RTU over RS-485. Only the SHT20 sensor is documented here.

Every value cites its sourcePinout not published

[Buy on Compoden](https://compoden.com/products/xy-md02-sht20-temperature-humidity-sensor-modbus-rtu-module)

## Specs

| Spec | Value | Source |
|---|---|---|
| Sensor supply voltage (SHT20 chip) | 2.1 V to 3.6 V, 3.0 V typ | source Electrical specification (p.2) |
| Humidity accuracy (SHT20, 25 C) | +/-3.0 %RH typ (maximum: Figure 2) | source Table 1 Relative Humidity (p.2) |
| Humidity normal operating range | 0 to 80 %RH (extended 0 to 100 %RH) | source Table 1 and footnote 4 (p.2) |
| Humidity resolution (SHT20) | 0.04 %RH at 12 bit; 0.7 %RH at 8 bit | source Table 1 (p.2) |
| Temperature accuracy (SHT20) | +/-0.3 C typ (maximum: Figure 3) | source Table 1 Temperature (p.2) |
| Temperature range (SHT20, extended) | -40 C to 125 C | source Table 1 (p.2) |
| Temperature resolution (SHT20) | 0.01 C at 14 bit; 0.04 C at 12 bit | source Table 1 (p.2) |
| Response time (63 percent) | Humidity 8 s; temperature 5 to 30 s | source Table 1 (p.2) |

## Pinout
We don't publish a pin table for this part: no official source we could verify gives one. Check the labels printed on your module, and see the notes below.

The Sensirion sheet covers only the SHT20 sensor. The module's RS-485 terminals, supply and Modbus settings are not covered by an official document.

## Build with it
Project ideas for the XY-MD02 Modbus temperature and humidity sensor. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.

- [Modbus temperature and humidity reader](https://app.soldr.ai/?prompt=I%20want%20to%20build%20a%20Modbus%20temperature%20and%20humidity%20reader%20with%20an%20ESP32%2C%20an%20XY-MD02%20module%2C%20a%20TTL%20to%20RS485%20converter%20and%20a%200.96%20inch%20OLED): The converter board takes 3.3 V or 5 V logic from the ESP32 and drives the RS-485 pair. Get the module's register map, baud rate and address from its own documentation first. The module's own supply is not documented here: check the module label for its supply voltage and RS-485 terminals before wiring, and power it accordingly.
- [Uno RS-485 climate display](https://app.soldr.ai/?prompt=I%20want%20to%20build%20an%20RS-485%20climate%20display%20with%20an%20Arduino%20Uno%2C%20an%20XY-MD02%20module%2C%20a%20MAX485%20module%20and%20a%2016x2%20I2C%20LCD): The Uno and the MAX485 module both work at 5 V logic. Check the module's own documentation for baud rate and address. The module's own supply is not documented here: check the module label for its supply voltage and RS-485 terminals before wiring, and power it accordingly.
- [Pico Modbus climate display](https://app.soldr.ai/?prompt=I%20want%20to%20build%20a%20Modbus%20climate%20display%20with%20a%20Raspberry%20Pi%20Pico%2C%20an%20XY-MD02%20module%2C%20a%20TTL%20to%20RS485%20converter%20and%20a%200.96%20inch%20OLED): The Pico's 3.3 V UART fits the converter's 3.3 V logic option. Learning project; confirm the module's register map before reading values. The module's own supply is not documented here: check the module label for its supply voltage and RS-485 terminals before wiring, and power it accordingly.

## Common mistakes

- Quoting the SHT20 chip supply (2.1-3.6 V) as the module's supply: the module board's supply range is not documented here (source: [link](https://sensirion.com/media/documents/CCDE1377/635000A2/Sensirion_Datasheet_Humidity_Sensor_SHT20.pdf), p.2)
- Expecting stable readings above 80 %RH for long periods: the sheet says long exposure outside the normal 0-80 %RH range can shift readings (source: [link](https://sensirion.com/media/documents/CCDE1377/635000A2/Sensirion_Datasheet_Humidity_Sensor_SHT20.pdf), Section 1.1 Operating range and footnote 4)

## Not covered by the official source

- No maker document for the XY-MD02 module; Modbus registers, baud rate, default address and supply are not stated.
- SHT20 values describe the sensor only.
- The module's supply voltage and RS-485 terminal labels are not in any maker document found; the ideas tell the builder to check the module label.

## Sources

- [link](https://sensirion.com/media/documents/CCDE1377/635000A2/Sensirion_Datasheet_Humidity_Sensor_SHT20.pdf) (Sensirion SHT20 datasheet, Version 5, October 2022)