KM31B05 RS485 Soil Conductivity Sensor

Introduction

The KM31B05 sensor is designed for easy integration with PLC, DCS, and other instruments or systems for monitoring soil conductivity. It features a high-precision sensing core for reliability and long-term stability. Various output methods are available, including RS232, RS485, CAN, 4-20mA, DC0-5V/10V, ZIGBEE, Lora, WIFI, and GPRS.

Technical Parameters

Product Selection

The product is divided into the following models based on the output method:

Product Size

The sensor has the following dimensions: Height: 122mm, Width: 48mm, Depth of sensor head: 39mm, Width of sensor head: 19mm, Cable connector height: 14mm.

Features

Waterproof Wiring

The cable is sealed to be anti-pull and anti-water.

Graphite Electrode

Features quick response and can be measured when buried in soil.

Wiring

RS485 Wiring

• RD: PWR+
• GN: PWR-
• YE: RS485 A+
• BU: RS485 B-

mA/V Wiring

• RD: PWR+
• BK: PWR-
• BU: mA\V Out

RS485 Wiring Diagram Description

Connects a computer port via an RS485 converter to the Soil EC Sensor.

mA/V Wiring Diagram Description

Connects a Current/Voltage Meter to the Soil EC Sensor using PWR+ (RD), PWR- (BK), and mA/V Out (BU).

Application Solution

This sensor is suitable for various applications, including greenhouses, industrial control systems, and water management systems.

Communication Protocol

The product uses the RS485 MODBUS-RTU standard protocol format for all operations and replies.

Default settings: Device Address: 1, Baud Rate: 9600, Data Bits: 8, Parity: None, Stop Bits: 1.

Command Interface and Data Handling

1. Read Data (Function ID 0x03)

To query device data, send an inquiry frame. Example: Querying data for device 1.

Example response data: 01 03 02 00 79 79 A6.

Data Description: Data is in hexadecimal. For example, 00 79 (hex) is 121 (decimal). With a magnification of 100, the actual value is 1.21.

2. Data Address Table

3. Read and Modify Device Address

(1) Read or Query Device Address

Use command FA 03 00 64 00 02 90 5F to query the device address if unknown (FA is general address 250).

Example response data: 01 03 02 07 12 3A 79.

Response data interpretation: First byte (01) is the real address. 55 3C (hex) is 20182 (decimal) for the main model. 00 01 indicates status quantity.

(2) Change Device Address

Example: Change address from 1 to 02 using command: 01 06 00 66 00 02 E8 14.

Successful change response: 02 06 00 66 00 02 E8 27. The new address takes effect immediately.

4. Read and Modify Baud Rate

(1) Read Baud Rate

Default baud rate is 9600. To read the current baud rate, use command: 01 03 00 67 00 01 35 D5.

Baud rate encoding: 1=2400, 2=4800, 3=9600, 4=19200, 5=38400, 6=115200.

Example response data: 01 03 02 00 03 F8 45.

Rate ID 03 indicates a baud rate of 9600.

(2) Change Baud Rate

Example: Change baud rate from 9600 (code 3) to 38400 (code 5) using command: 01 06 00 67 00 05 F8 16.

The new baud rate takes effect immediately. The device may lose response until the query command is updated.

5. Read Correction Value

(1) Read Correction Value

Correction values adjust display errors. Range: +/- 1000 (0-1000 or 64535-65535). To add 100, use command: 01 03 00 6B 00 01 F5 D6.

Example response data: 01 03 02 00 64 B9 AF.

The first byte (01) is the device address. 00 6B is the first state quantity correction value register. Other parameters operate similarly.

(2) Change Correction Value

Example: To add 1 to the true value (equivalent to adding 100 correction): 01 06 00 6B 00 64 F9 FD.

The parameters take effect immediately after successful change.

Analog Output Calculation Examples

4-20mA Output (Range 0~2000)

Formula: C = (A2-A1) * (X-B1) / (B2-B1) + A1

Where: A2=Range Upper Limit (2000), A1=Range Lower Limit (0), B2=Current Output Range Upper Limit (20mA), B1=Current Output Range Lower Limit (4mA), X=Currently Read Value, C=Calculated Current Value.

Example: When measuring 8mA, the current value is 500.0.

0-5V Voltage Output (Range 0~2000)

Formula: C = (A2-A1) * (X-B1) / (B2-B1) + A1

Where: A2=Range Upper Limit (2000), A1=Range Lower Limit (0), B2=Voltage Output Range Upper Limit (5V), B1=Voltage Output Range Lower Limit (0V), X=Currently Read Value, C=Calculated Voltage Value.

Example: When measuring 2.5V, the current voltage is 1000.0.

0-10V Voltage Output (Range 0~2000)

Formula: C = (A2-A1) * (X-B1) / (B2-B1) + A1

Where: A2=Range Upper Limit (2000), A1=Range Lower Limit (0), B2=Voltage Output Range Upper Limit (10V), B1=Voltage Output Range Lower Limit (0V), X=Currently Read Value, C=Calculated Voltage Value.

Example: When measuring 5V, the current voltage is 1000.0.

Disclaimer

This document provides information about the product. Shanghai Sonbest Industrial Co., Ltd. makes no warranties and assumes no liability regarding the sale and use of this product. Specifications may change without notice.

Contact Us

Company: Shanghai Sonbest Industrial Co., Ltd KLHA Brand Division

Address: Building 8, No. 215 North East Road, Baoshan District, Shanghai, China

Web: http://www.klha.com/

SKYPE: soobuu

Email: sale@sonbest.com

Tel: 86-021-51083595 / 66862055 / 66862075 / 66861077