Factory Direct LF-0020 Water Temperature Sensor - Premium Quality And Competitive Prices

Technique Parameter

Measurement range	-50～100℃
Measurement range	-20～50℃
Accuracy	±0.5℃
Power supply	DC 2.5V
	DC 5V
	DC 12V
	DC 24V
	Other
Out-put	Current: 4～20mA
	Voltage: 0～2.5V
	Voltage: 0～5V
	RS232
	RS485
	TTL Level: (frequency; Pulse width)
	Other
Line length	Standard: 10 meters
Line length	Other
Load capacity	Current output impedance≤300Ω
Load capacity	Voltage output impedance≥1KΩ
Operating environment	Temperature: -50℃～80℃
Operating environment	Humidity: ≤100%RH
Produce weight	Probe 145 g, with collector 550 g
Power dissipation	0.5 mW

Calculation Formula

Voltage type (0～5V): T=V / 5 × 70 -20 (T is the measured temperature value (℃), V is the output voltage (V), this formula corresponds to the measurement range -20 ~ 50 ℃) T=V / 5 × 150 -50 (T is the measured temperature value (℃), V is the output voltage (V), this formula corresponds to the measurement range -50 ~ 100 ℃) Current type (4～20mA) T=（I-4）/ 16 × 70 -20 (T is the measurement temperature value (℃), I is the output current (mA), this type corresponds to the measurement range -20 ~ 50 ℃) T=(I-4)/ 16 × 150 -50 (T is the measured temperature value (℃), I is the output current (mA), this formula corresponds to the measurement range -50 ~ 100 ℃) Note: The calculation formulas corresponding to different signal outputs and different measurement ranges need to be recalculated!

Wiring Method

1. If equipped with a weather station produced by our company, directly connect the sensor to the corresponding interface on the weather station using the sensor cable. 2. If the transmitter is purchased separately, the matching cable sequence of the transmitter is:

Line color	Output signal
Line color	Voltage type	Current type	Communication type
Red	Power+	Power+	Power+
Black (green)	Power ground	Power ground	Power ground
Yellow	Voltage signal	Current signal	A+/TX
Blue			B-/RX

3. Transmitter voltage and current output wiring:

Wiring for voltage output mode

Wiring for current output mode

(Water temperature sensor)

MODBUS-RTUProtocol

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 01	Read points
XX XX	CRC Check code,front low later high

Returns: Adress 03 02 XX XX XX XX

Code	Function definition	Note
Adress	Station number (address)
03	Function code
02	Read unit byte
XX XX	Soil temperature data (high before, low after)	Hex
XX XX	Soil humidity data (high before, low after)

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.

RS485 Circuit

Instructions for use

Connect the sensor according to the instructions in the wiring method, and then insert the sensor probe into the soil to measure the temperature, and supply power to the collector and the sensor to obtain the water temperature at the measurement point.

Precautions

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.

Troubleshooting

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.

Structure Size

Sensor Size

(Water temperature sensor)

Selection table

Number	Power supply mode	Output signal	Explain
LF-0020			Water temperature sensor
	5V-		5V powered
	12V-		12V powered
	24V-		24V powered
	YV-		Other powered
		0	No change
		V	0-5V
		V1	1-5V
		V2	0-2.5V
		A1	4-20mA
		A2	0-20mA
		W1	RS232
		W2	RS485
		TL	TTL
		M	Pulse
		X	Other
For example: LF-0020-24V-A1: water temperature sensor (transmitter) 24V power supply, 4-20mA output

LF-0020 water temperature sensor

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