Temperature & Humidity Sensor

Temperature & Humidity Sensor

A wired temperature and humidity sensor with RS485 / Modbus RTU output, a 5 V DC supply and configurable device address and baud rate

Discuss this model

Key features

  • Temperature and humidity readings over RS485 using the standard Modbus RTU protocol, with device addresses and baud rates configurable in PC software.
  • Temperature accuracy ±0.5°C at 25°C; humidity accuracy ±4%RH at 25°C within 5%RH–95%RH, with a 1-second update interval.
  • Built-in EMC interference suppression and reverse-polarity protection, with maximum power consumption ≤0.05 W from a 5 V DC supply.

Functions in detail

Temperature and humidity measurement

  • Resolution of 0.1°C and 0.1%RH; readings update every 1 second.
  • Long-term stability: temperature ≤0.1°C/year and humidity ≤1%RH/year.
  • At an air speed of 1 m/s, response time is ≤15s for temperature and ≤4s for humidity.

RS485 bus communication

  • Standard Modbus RTU with a stated maximum communication distance of up to 2000 m; check the actual cable, topology and site conditions.
  • Multiple sensors can share a bus; each device must have a unique communication address.
  • Factory settings: 9600bit/s, address 0x01, 8 data bits, no parity, 1 stop bit and CRC checking.

Register access and configuration

  • Read humidity at 0000H (PLC 40001) and temperature at 0001H (PLC 40002), using function 03.
  • Returned measurement values are multiplied by 10; negative temperatures use two’s-complement representation.
  • Device address at 07D0H and baud rate at 07D1H support functions 03 and 06; PC software can read and change these settings.

Power and wiring

  • Red wire: 5 V DC positive; black wire: power negative.
  • Yellow wire: 485-A; green wire: 485-B. Do not swap A and B.
  • The sensor includes EMC interference suppression and power reverse-polarity protection.

Technical specifications

Parameter Specification
Power supply 5 V DC
Maximum power consumption ≤0.05 W
Humidity accuracy ±4%RH (5%RH~95%RH, 25°C)
Temperature accuracy ±0.5°C (25°C)
Operating environment -40°C to +80°C; 0%RH~100%RH
Communication protocol Modbus RTU
Output signal RS485
Temperature resolution 0.1°C
Humidity resolution 0.1%RH
Temperature/humidity update interval 1s
Long-term stability Temperature ≤0.1°C/year; humidity ≤1%RH/year
Response time Temperature ≤15s (air speed 1 m/s); humidity ≤4s (air speed 1 m/s)
Configuration method PC software
Encoding 8-bit binary
Data bits 8 bits
Parity None
Stop bits 1 bit
Error checking CRC
Factory baud rate 9600bit/s
Factory device address 0x01
Wiring: red Power positive, 5 V DC
Wiring: black Power negative
Wiring: yellow 485-A
Wiring: green 485-B
Register 0000H PLC 40001; humidity ×10; read-only; function 03
Register 0001H PLC 40002; temperature ×10; read-only; function 03
Register 07D0H PLC 42001; device address; read/write; functions 03, 06
Register 07D1H PLC 42002; baud rate; read/write; functions 03, 06

Installation and configuration

Use a 5 V DC supply and check the receiving device supports RS485 and Modbus RTU. Follow the wire colours and A/B polarity, assign a unique address to each sensor on the bus, and match the baud rate and serial settings. Confirm readings and register scaling in the connected system before deployment.