1.System Overview
The S-CZDD integrated online turbidity sensor is designed and manufactured based on the principle of scattered light turbidity measurement method. When a beam of light enters a water sample, the light is scattered due to the turbidity substances in the water sample. By measuring the intensity of the scattered light perpendicular to the incident light and comparing it with the internal calibration value, the turbidity in the water sample is calculated and linearized to output the final value.
1.1Features

• 90 ° angle scattered light principle, built-in temperature sensor
• Supports RS-485, Modbus/RTU protocols
• Fiber optic structure with strong resistance to external light interference
• Infrared LED light source, high stability
• IP68 protection, within 20 meters of water depth
• Convenient, fast, stable, and easy to maintain

1.2 Technical Parameters

model	S-SCZD
Measuring principle	scattered light method
Range/Resolution	0～20.00NTU	0.01NTU/0.1℃
	0～100.0NTU	0.1NTU/0.1℃
	0～1000.0NTU	0.1NTU/0.1℃
precision	± 5% or ± 3NTU (0-1000.0NTU) ± 3% or ± 2NTU (0-1000NTU) ± 3% or ± 1.5NTU (0-20.00NTU) ±0.3℃
calibration method	Two-point calibration
temperature compensation	Automatic temperature compensation (Pt1000)
output method	RS-485(Modbus/RTU)
working conditions	0～50℃，<0.2MPa
Storage temperature	-5～65℃
Shell material	POM、ABS
Installation method	Immersion installation, 3/4 "NPT pipe thread
Cable length	5 meters, other lengths can be customized
power consumption	0.2W@12V
power supply	12～24VDC
Protection level	IP68

1.2.1 Dimensional drawing

Note: The sensor connector is a male M16-5 core waterproof connector
1.3Product Selection

S-					Company Code Name
	SCZD				turbidity sensor
		N01-			RS485. MODBUS protocol
			1-		First generation shell
				1000	0-1000NTU range

2. Equipment installation

2.1 Installation

Installation distance requirement: Keep at least 5cm from the side wall and at least 10cm from the bottom.

2.2 Electrical Connections

The cable is a 4-core twisted pair shielded wire, and the line sequence is defined as follows:

• Red wire - power cord (12-24VDC)
• Black wire - Ground wire (GND)
• Blue line -485A
• White line -485B

Before powering on, carefully check the wiring sequence to avoid unnecessary losses caused by wiring errors.
Wiring instructions:Considering that cables are immersed in water (including seawater) or exposed to air for a long time, waterproof treatment is required for all wiring points, and user cables should have a certain degree of corrosion resistance.

3. Maintenance and upkeep

3.1 Maintenance Procedures and Methods

3.1.1 Maintenance Schedule

The cleanliness of the measurement window is crucial for maintaining accurate readings.

maintenance task	Suggested maintenance frequency
Calibrate sensors (if required by regulatory authorities)	According to the maintenance schedule required by the supervisory department

3.2.2 Maintenance Methods

• Outer surface of sensor: Clean the outer surface of the sensor with tap water. If there are still debris residue, wipe it with a damp soft cloth. For stubborn dirt, add some household detergent to tap water to clean it.
• Check the cable of the sensor: During normal operation, the cable should not be tightened, otherwise it may cause the internal wires of the cable to break, making the sensor unable to work properly.
• Check if the measurement window of the sensor is dirty and if the cleaning brush is functioning properly.

3.3.3 Precautions

Sensors contain sensitive optical and electronic components. Ensure that the sensor is not subjected to severe mechanical impact. There are no components inside the sensor that require user maintenance.

3.2 Calibration of Sensors

1. Zero point calibration: Use a larger beaker to measure an appropriate amount of zero turbidity liquid, place the sensor vertically in the solution, and measure the end face of the sensor at least 10cm away from the bottom of the beaker. Wait for 3-5 minutes until the value stabilizes before performing zero point calibration. Refer to the appendix for instructions.
2. Slope calibration: Place the sensor measurement end face in a standard solution, with the sensor measurement end face at least 10cm away from the bottom of the beaker. Wait for 3-5 minutes until the value stabilizes before performing slope calibration. Refer to the appendix for instructions.

3.3 Frequently Asked Questions and Answers

problem	Possible reasons	solution
The operation interface cannot connect or does not display measurement results	The measurement value is too high, too low, or the value remains unstable	Reconnect the controller and cables
	Cable malfunction	Contact us
The measurement value is too high, too low, or the value remains unstable	The sensor window is attached by external objects	Clean the surface of the sensor window

Appendix Data Communication

1. Data format

The default data format for Modbus communication is 9600 n、 8. 1 (baud rate 9600bps, 1 start bit, 8 data bits, no checksum, 1 stop bit).
2.Information frame format(xxRepresenting one byte)

a) Read data instruction frame
06	03	xx	xx xx	xx xx
address	function code	Register starting address	number of registers	CRC checksum (low byte first)

b) Read data response frame
06	03	xx	xx……xx	xx xx
address	function code	byte count	Response data	CRC checksum (low byte first)
c) Write data instruction frame
06	06	xx xx	xx xx	xx xx
address	function code	register address	write data	CRC checksum (low byte first)
d) Write data response frame (same as write data instruction frame)
06	06	xx xx	xx xx	xx xx
address	function code	register address	write data	CRC checksum (low byte first)

3. Register address

register address	name		Instructions		number of registers		Access method
40001 (0x0000)	Measurement value+temperature		Four double byte integers, representing the measured value, the decimal places of the measured value, the temperature value, and the decimal places of the temperature value.		4 (8 bytes)		read
44097 (0x1000)	zero point calibration		The range of 0-20NTU is 0-10NTU Calibration in turbidity solution, writing data as standard Actual value of quasi solution multiplied by 100; 0 ～ 100NTU range from 0 to 20NTU turbidity Calibration in liquid, writing data as standard Actual value of the solution multiplied by 10; 0～1000NTU Range in 0-200NTU turbidity solution Calibration, writing data as actual standard solution Inter value x 10; Read data with zero bias Move quantity.		1 (2 bytes)		write
44101 (0x1004)	slope calibration		The range of 0-20NTU is between 10 and Calibration in 100NTU turbidity solution, with data written as the actual value of the standard solution multiplied by 100;		1 (2 bytes)		write
				0~100NTU with a range of 20~ Calibration in 200NTU turbidity solution, with data written as the actual value of the standard solution multiplied by 10; The range of 0-1000NTU is between 200 and Calibration in 1000NTU turbidity solution, with data written as the actual value of the standard solution ×10 ； Read the data as slope values X 1000.
44113 (0x1010)		temperature calibration		Calibrate in solution and write data as real International temperature value x 10; Read the data as temperature calibration offset x 10.		1 (2 bytes)		write
48195 (0x2002)		Sensor address		The default is 6, and the data range for writing is 1-127.		1 (2 bytes)		write
48225 (0x2020)		Reset sensor		The calibration value is restored to the default value, and the written data is 0. Note that after resetting the sensor, it is necessary to Re calibrate before use.		1 (2 bytes)		write

4. Command Examples

a) Start measuring instruction
Function: Obtain turbidity and temperature measured by sensors; The unit of temperature is ℃, and the unit of turbidity is NTU. Request frame: 06 03 00 00 04 45 BE
Response frame: 06 03 08 01 02 00 01 00 B0 00 01 90 48
Reading example:

Turbidity value	temperature value
01 02 00 01	00 B0 00 01

For example, turbidity values 01 and 02 represent hexadecimal readings of turbidity values, 00 and 01 represent turbidity values with one decimal point, converted to decimal values of 25.8.
The temperature value 00 B0 represents the hexadecimal reading temperature value, and 00 01 represents the temperature value with one decimal point converted to a decimal value of 17.6.
b) Calibration instruction
zero point calibration
Function: Set the zero calibration value of the sensor; Zero point calibration is performed in zero turbidity water, for example: Request frame: 06 06 10 00 00 8C BD
Response frame: 06 06 10 00 00 8C BD
slope calibration
Function: Set the slope calibration value of the sensor;
For products with ranges of 0-1000NTU and 0-100NTU, the slope calibration example is as follows (calibrated in 1000NTU standard solution, with a written value of 1000x10, i.e. 0x2710):
Request frame: 06 06 10 04 27 10 D7 40