Soil Moisture and Temperature Sensor Interface

The sensor is a combination of soil moisture and soil temperature sensors. It has the advantages of convenient carrying, sealing and high precision. It is an ideal choice for soil moisture and soil temperature measurement.

The soil moisture part is a high-precision, high-sensitivity sensor manufactured by high-frequency electronic technology based on the principle of frequency domain reflection. By measuring the dielectric constant of soil, it can directly and stably reflect the true moisture content (volume water content) of various soils. It is the most popular soil moisture measurement method in the world.

The soil temperature is partly composed of the German-class imported Class A ST-1-PT1000 precision platinum resistance and high-precision transmitter. The transmitter part is composed of a power module, a temperature sensing module, a transmission module, a temperature compensation module, and a data processing module, and has high applicability to the use environment.

Supplies

Step 1: Hardware Assembly

First Of All, you need to download on your pc Docklight serial interface to make sure that the sensor is working well.

then Please pay attention the wire connect order:

1.Sensor Red (Brown) wire connect the power positive 5-12VDC

2.Sensor black wire connect the power negative

3.Sensor yellow wire connect the RS485-USB converter RS485A (it shows “A” or “D+” in the converter)

4.Sensor Green(blue) wire connect the RS485-USB converter RS485B (it shows” B” or “D-” in the converter)

Step 2: Docklight Settings

Ensure that the USB to RS485 driver is installed. If it doesn't appear as shown in the above photo, please install the driver from the following link.

in my situation the USB reserved COMPORT number "COM27" and I will change settings from Docklight settings bar as shown setting.

Send/Receive on Comm: COM27

Baud rate: 9600.

Party Bit: None.

Stop Bit: one.

Data Bits: eight.

then click Ok the save the settings that we had chosen.

Step 3: Test Sensor on PC

using Docklight we are going to test the sensor using the following command

0X01 0X03 0X00 0X00 0X00 0X02 0XC4 0X0B

Address to the sensor: 0X01
Function code for reading from the register: 0X03
Reserved start addresses bytes: 0X00 0X00
Reserved number of registers bytes: 0X00 0X02
CRC/Modbus 16-bit: 0XC4 0X0B

This command structure is utilized for testing the "soil moisture and temperature" sensor.

and then the sensor response like this.

Address: 0X01
Function code: 0X03
Data length: 0X04
Register 0 data high: 0X00Soil Temperature: 15.1 ℃ (Converted from hexadecimal to decimal, divided by 10, using the complement algorithm for negative numbers)
Register 0 data low: 0X97
Register 1 data high: 0X01Soil Moisture: 35.6% (Converted from hexadecimal to decimal, divided by 10)
Register 1 data low: 0X64
Low CRC16: 0X4B
High CRC16: 0XA4