Soil temperature and humidity sensor soil transmitter

Soil temperature and humidity sensor is a high-precision, high-sensitivity soil moisture and temperature measuring instrument. The sensor uses the principle of electromagnetic pulse to measure the apparent dielectric constant of the soil, so as to obtain the true moisture content of the soil. It is fast, accurate, stable and reliable, and is not affected by fertilizers and metal ions in the soil.This instrument can be widely used in agriculture, forestry, geology, construction and other industries.

Products Details

Technique Parameter

Measurement range soil moisture 0 ~ 100% soil temperature -20 ~ 50 ℃
Soil wet resolution 0.1%
Temperature resolution 0.1 ℃
Soil wet accuracy ± 3%
Temperature accuracy ± 0.5 ℃
Power supply mode DC 5V 
DC 12V 
DC 24V 
Output form Current: 4~20mA 
Voltage: 0~2.5V 
Voltage: 0~5V    
TTL Level: (frequency; Pulse width)
Load resistance Voltage type: RL≥1K
Current type: RL≤250Ω
Working temperature -50 ℃ ~ 80 ℃
Relative humidity 0 to 100%
Product weight 220 g probe with transmitter 570 g
Product power consumption about 420 mW

Calculation Formula

Soil humidity: Voltage type (0 ~ 5V output): R = V / 5 × 100% (R is the soil moisture value and V is the output voltage value (V)) Current type (4 ~ 20mA output): R = (I-4) / 16 × 100% (R is the soil moisture value, I is the output current value (mA)) Soil temperature: Voltage type (0 ~ 5V output): T = V / 5 × 70-20 (T is the measured temperature value (℃), V is the output voltage value (V), this formula corresponds to the measurement range -20 ~ 50 ℃) Current type (4 ~ 20mA) T = (I-4) / 16 × 70 -20 (T is the measured temperature value (℃), I is the output current (mA), this formula corresponds to the measurement range -20 ~ 50 ℃)

Wiring Method          

1. If equipped with a weather station produced by the company, directly connect the sensor to the corresponding interface on the weather station using a sensor line; 2. If the transmitter is purchased separately, the corresponding line sequence of the transmitter is:
Line color Output signal
Voltage Current communication
Red Power + Power + Power +
Black(green) Power ground Power ground Power ground
Yellow Voltage signal Current signal A+/TX
Blue     B-/RX
Transmitter voltage and current output wiring:

Wiring for voltage output mode

Wiring for current output mode

Structure Dimensions

Sensor Size


1. The serial format Data bits 8 bits Stop bit 1 or 2 Check Digit None Baud rate 9600 Communication interval is at least 1000ms 2. Communication format [1] Write device address Send: 00 10 Adress CRC (5 bytes) Returns: 00 10 CRC (4 bytes) Note: 1. The address bit of the read and write address command must be 00. 2. Adress is 1 byte and the range is 0-255. Example: Send 00 10 01 BD C0 Returns 00 10 00 7C [2] Read device address Send: 00 20 CRC (4 bytes) Returns: 00 20 Adress CRC (5 bytes) Explanation: Adress is 1 byte, the range is 0-255 For example: Send 00 20 00 68 Returns 00 20 01 A9 C0 [3] Read real-time data Send: Adress 03 00 00 00 02 XX XX Note: as shown below
Code Function definition Note
Adress Station number (address)  
03 Function code  
00  00 Initial address  
00  02 Read points  
XX XX CRC Check code,front low later high  
Returns: Adress 03 04 XX XX XX XX YY YY Note
Code Function definition Note
Adress Station number (address)  
03 Function code  
04 Read unit byte  
XX  XX Soil temperature data (high before, low after) Hex
XX  XX Soil humidity data (high before, low after) Hex
YY  YY CRCCheck code  
To calculate the CRC code: 1. The preset 16-bit register is FFFF in hexadecimal (that is, all are 1). Call this register the CRC register. 2. XOR the first 8-bit data with the lower bit of the 16-bit CRC register and put the result in the CRC register. 3. Shift the contents of the register to the right by one bit (toward the low bit), fill the highest bit with 0, and check the lowest bit. 4. If the least significant bit is 0: repeat step 3 (shift again), if the least significant bit is 1: the CRC register is XORed with the polynomial A001 (1010 0000 0000 0001). 5. Repeat steps 3 and 4 until 8 times to the right, so that the entire 8-bit data has been processed. 6. Repeat steps 2 to 5 for the next 8-bit data processing. 7. The CRC register finally obtained is the CRC code. 8. When the CRC result is put into the information frame, the high and low bits are exchanged, and the low bit is first.

Instructions for use

Connect the sensor according to the instructions in the wiring method, then insert the probe pins of the sensor into the soil to measure humidity, and turn on the power and the collector switch to obtain the soil temperature and humidity at the measurement point.


1. Please check whether the packaging is intact and check whether the product model is consistent with the selection. 2. Do not connect with power on, and then power on after checking the wiring. 3. Do not arbitrarily change the components or wires that have been soldered when the product leaves the factory. 4. The sensor is a precision device. Please do not disassemble it by yourself or touch the surface of the sensor with sharp objects or corrosive liquids in order to avoid damaging the product. 5. Please keep the verification certificate and certificate of conformity, and return it with the product when repairing.

Selection Table

No Power supply Output Signal Instructions
LF-0008-     Soil temperature and humidity sensor
    5V-   5V power supply
12V-   12V power supply
24V-   24V power supply
YV-   Other power
  V 0-5V
V2 0-2.5V
A1 4-20mA
W1 RS232
W2 RS485
M Pulse
X Other
E.g.:  LF-0008-12V-A1:Soil temperature and humidity sensor 12V power supply, 4-20mA current signal output


1. When the output is detected, the display indicates that the value is 0 or is out of range. Check whether there is obstruction from foreign objects. The collector may not be able to obtain the information correctly due to wiring problems. Please check whether the wiring is correct and firm; 2. If it is not the above reasons, please contact the manufacturer.

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