SONBEST SC7232 Soil Moisture Temperature Controller User Manual

1. Introduction

The SONBEST SC7232 is an intelligent soil moisture and temperature controller designed for automatic watering, irrigation, and environmental monitoring. It consists of a controller instrument and a soil moisture sensor, offering high reliability and stability for various applications. This device features simple operation, high precision, and cost-effectiveness, making it suitable for scientific experiments, water-saving irrigation, greenhouses, flower and vegetable cultivation, grassland pastures, and sewage treatment.

Equipped with an RS485 communication interface and supporting the MODBUS-RTU communication protocol, the SC7232 allows for real-time monitoring, control, and data integration with PLCs, human-machine interfaces, and other systems. Users can easily query and set control parameters and data.

2. Key Features

• Dual Control: Manages both soil moisture and temperature.
• Return Difference Design: Prevents frequent relay operation, extending equipment life.
• High-Quality Probe: Made of 316 stainless steel for strong strength, corrosion resistance, and long-term electrolysis resistance.
• RS485 Communication: Utilizes MODBUS-RTU protocol for real-time data query and integration with other systems.
• Fast Response Speed: Ensures high transmission efficiency.
• Durable Cable: Signal cable is designed to be corrosion-resistant.
• Configurable Settings: Allows setting of thresholds and return differences.
• Multiple Control Modes: Offers three distinct control modes for versatile application.
• Simple Configuration: Stable and reliable performance with straightforward setup.
• Accurate Measurement: Provides precise readings for soil moisture and temperature.

Figure 2.1: Key features of the SC7232 controller.

Figure 2.2: Advanced features and capabilities.

3. Technical Specifications

Dimensions

Figure 3.1: Controller dimensions (72mm x 72mm x 110mm) and sensor dimensions (45mm x 80mm x 26mm probe length).

4. Package Contents

The product package typically includes the following items:

• SONBEST SC7232 Intelligent Soil Moisture Temperature Controller
• Soil Moisture Sensor (integrated with cable)
• Warm Reminder Card
• Certificate of Conformity

Figure 4.1: Contents of the product package.

5. Setup and Installation

5.1. Wiring Instructions

Carefully follow the wiring diagram below to connect the sensor and power to the controller. If the product does not have pre-attached leads, refer to the core wire colors for guidance.

Figure 5.1: Controller wiring diagram.

Sensor Wiring (Left Side):

• Pin 1 (RED): Sensors V+
• Pin 2 (GREEN): Sensors V-
• Pin 3 (NULL): Empty
• Pin 4 (BLUE): Sensors B1-
• Pin 5 (YELLOW): Sensors A1+
• Pin 6: RS485 B-
• Pin 7: RS485 A+

Power and Relay Wiring (Right Side):

• Pin 8 (BROWN): L (Power supply AC220V)
• Pin 9 (BLUE): N (Power supply AC220V)
• Pin 10 (COM): Public End
• Pin 11 (NC1): Relay 1 Normally Closed
• Pin 12 (NO1): Relay 1 Normally Open Point
• Pin 13 (NC2): Relay 2 Normally Closed
• Pin 14 (NO2): Relay 2 is Always On

For loads less than 800W, direct connection is possible. For loads exceeding 800W, an AC contactor must be used.

Figure 5.2: Example wiring for AC contactor and heating tubes.

5.2. Sensor Placement

Proper sensor placement is crucial for accurate readings and effective control. The sensor can be used for both burial investigation and fast measurement.

• Burial Investigation: For long-term monitoring, bury the sensor at the desired depth. Ensure the RS485 converter is connected to sync data to a computer.
• Fast Measurement: Select a suitable measurement location, avoiding rocks. Dig the topsoil to the required depth, maintaining the original tightness of the lower soil. Hold the sensor and insert it vertically into the soil. Do not swing it from side to side to ensure close contact with the soil.

Figure 5.3: Sensor application methods.

6. Operation

6.1. Panel Layout and Key Functions

The controller features a clear panel layout with digital displays for moisture and temperature, and several control keys.

Figure 6.1: Controller front panel.

• ≫ (Select Key): Used to select position during setting.
• ∧ (Up Key): Increases the value or moves up.
• ∨ (Down Key): Decreases the value or moves down.
• SET (Set Key): Enters setting mode and confirms selections.

The upper display shows the humidity value, and the lower display shows the temperature value.

Figure 6.2: Detailed key operation for setting parameters.

6.2. Setting Parameters

The controller supports setting upper and lower thresholds, return difference, and control modes.

1. Upper Threshold Setting:
   • Click "SET" once to enter the upper threshold setting.
   • Press "≫" to select the digit position, then "∧" or "∨" to adjust the value.
   • Applicable for control modes 1 and 3. If the measured value exceeds this threshold, Relay 1 will activate.
   • Range: Humidity 0-100.0%, Temperature -99-99.9℃.
2. Lower Threshold Setting:
   • Click "SET" twice to enter the lower threshold setting.
   • Press "≫" to select the digit position, then "∧" or "∨" to adjust the value.
   • Applicable for control modes 2 and 3. If the measured value falls below this threshold, Relay 2 will activate.
   • Range: Humidity 0-100.0%, Temperature -99-99.9℃.
3. Control Hysteresis (Return Difference) Setting:
   • Click "SET" three times to enter the control hysteresis setting.
   • Press "≫" to select the digit position, then "∧" or "∨" to adjust the value.
   • Range: Humidity 0-5.0%, Temperature 0-5.0%.
4. Control Mode Setting:
   • Click "SET" four times to enter the control mode setting.
   • Press "≫" to select the digit position, then "∧" or "∨" to adjust the value.
   • Mode 1: Action exceeding the upper threshold.
   • Mode 2: Action below the lower threshold.
   • Mode 3: Action above the upper threshold AND below the lower threshold.

6.3. Control Modes and Processes

The controller supports three distinct control modes, each with specific relay activation logic.

Figure 6.3: Control mode diagrams and processes.

1. Mode 1: Action Above Upper Threshold (Only Relay 1 in use)
   • Relay 1 Activation Condition: Measured value > Upper threshold + Return difference.
   • Relay 1 Release Condition: Measured value < Upper threshold - Return difference.
   • Process: When the measured value exceeds the upper limit threshold plus the return difference, Relay 1 activates (closes), turning on the connected device. When the measured value drops to the upper limit threshold minus the return difference, Relay 1 deactivates (opens), turning off the device.
2. Mode 2: Action Below Lower Threshold (Only Relay 2 in use)
   • Relay 2 Activation Condition: Measured value < Lower limit threshold - Return difference.
   • Relay 2 Release Condition: Measured value > Lower limit threshold + Return difference.
   • Process: When the measured value falls below the lower limit threshold minus the return difference, Relay 2 activates (closes), turning on the connected device. When the measured value rises to the lower limit threshold plus the return difference, Relay 2 deactivates (opens), turning off the device.
3. Mode 3: Over/Under Threshold Operation (Relay 1 and Relay 2 in use)
   • Relay 1 Activation Condition: Measured value > Upper threshold + Return difference.
   • Relay 2 Activation Condition: Measured value < Lower limit threshold - Return difference.
   • Process: This mode is typically used to control the forward and reverse rotation of motor equipment. When the measured value is higher than the upper limit value plus the return difference, Relay 1 activates. When the value is lower than the lower limit value minus the return difference, Relay 2 activates.

6.4. RS485 Communication Protocol (MODBUS-RTU)

The SC7232 uses the standard MODBUS-RTU protocol. All commands and replies are in hexadecimal data. The default device address is 1, and the default baud rate is 9600, 8 data bits, no parity (8, N, 1).

6.4.1. Common Data Address Table

6.4.2. Reading and Modifying Device Address

To query the device address when only one device is on the bus, send the command: FA 03 00 66 00 01 71 9E. The device will respond with its actual address (e.g., 01 03 02 00 01 79 84 where 01 is the real address).

To change the device address (e.g., from 1 to 2), send the command: 01 06 00 66 00 02 E8 14. The device will respond with the new address (e.g., 02 06 00 66 00 02 E8 27). The change takes effect immediately.

6.4.3. Reading and Modifying Baud Rate

The default baud rate is 9600. To read the current baud rate ID, send the command: 01 03 00 67 00 01 35 D5. The response (e.g., 01 03 02 00 03 F8 45 where 03 indicates 9600 baud) will show the current setting.

To change the baud rate (e.g., from 9600 to 38400, which corresponds to code 5), send the command: 01 06 00 67 00 05 F8 16. The new baud rate takes effect immediately, and the device will temporarily lose response until reconfigured.

6.4.4. Reading and Modifying Correction Value

Correction values can be adjusted to compensate for measurement errors, ranging from -1000 to 1000. To read the correction value, send the command: 01 03 00 6B 00 01 F5 D6. The response (e.g., 01 03 02 00 64 B9 AF where 00 64 is the correction value) will indicate the current setting.

To modify the correction value (e.g., add 100, which is 00 64 in hex), send the command: 01 06 00 6B 00 64 F9 FD. The parameters will take effect immediately after a successful change.

7. Maintenance

To ensure the longevity and accurate operation of your SONBEST SC7232 controller and sensor, consider the following maintenance tips:

• Keep Clean: Regularly clean the sensor probes to prevent buildup of soil or debris that could affect measurement accuracy. Use a soft cloth and avoid abrasive materials.
• Inspect Wiring: Periodically check all wiring connections for any signs of wear, corrosion, or loose terminals. Ensure connections are secure.
• Environmental Protection: While the device is designed for outdoor use, protect the controller unit from direct heavy rain or extreme weather conditions if possible, to prolong its lifespan.
• Software Updates: If available, check the manufacturer's website for any firmware or software updates for the controller to ensure optimal performance and compatibility.

8. Troubleshooting

If you encounter issues with your SONBEST SC7232, refer to the following common problems and solutions:

• No Power/Display Off:
  • Check the AC185~265V power supply connection.
  • Ensure the power cable is securely connected to the controller.
  • Verify the power source is active.
• Inaccurate Readings:
  • Ensure the sensor probes are clean and free of debris.
  • Verify the sensor is fully inserted into the soil and making good contact.
  • Check for proper calibration. If necessary, adjust the correction value via RS485 communication (refer to section 6.4.4).
  • Confirm the sensor is not damaged.
• Relay Not Activating/Deactivating:
  • Check the set upper/lower thresholds and return difference values (refer to section 6.2).
  • Verify the selected control mode is appropriate for your application (refer to section 6.3).
  • Ensure the external device connected to the relay is functioning correctly and its power requirements are met (e.g., using an AC contactor for high loads).
  • Inspect relay wiring for loose connections.
• RS485 Communication Issues:
  • Verify the RS485 wiring (A+, B-) is correct and secure.
  • Check the device address and baud rate settings (refer to sections 6.4.2 and 6.4.3). Ensure they match your communication software settings.
  • Confirm the RS485 converter is working properly and connected to the computer.
  • Ensure no other devices on the RS485 bus have conflicting addresses.

If the problem persists after following these steps, please contact customer support.

9. Warranty and Support

SONBEST products are designed for long-term maintenance and are professional and reliable. This product comes with a one-year warranty.

Figure 9.1: Warranty and reliability information.

9.1. Disclaimer

This document provides information about the product and does not grant any license to intellectual property. It does not express or imply, and prohibits any other means of granting any intellectual property rights. No liability is assumed. The company makes no warranties, express or implied, regarding the sale and use of this product, including suitability for specific use, marketability, or infringement liability for any patent, copyright, or other intellectual property rights. Product specifications and descriptions may be modified at any time without notice.

9.2. Contact Information

For support or inquiries, please contact:

• Company: Shanghai Sonbest Industrial Co., Ltd
• Address: Building 8, No.215 North east road, Baoshan District, Shanghai, China
• Website: http://www.sonbest.com/
• Email: sale@sonbest.com
• Phone: 86-021-51083595 / 66862055 / 66862075 / 66861077

10. Additional Resources

For the complete user manual and product literature, you can download the PDF version from the official website:

Download Full User Manual (PDF)

Figure 10.1: Product literature download prompt.