Liquid Level Sensor-FS-IR02 SKU: SEN0205

From DFRobot Electronic Product Wiki and Tutorial: Arduino and Robot


This is a photoelectric liquid level sensor that is operates using optical principles. The advantages of this are good sensitivity and no need for mechanical parts - meaning less calibration! The corrosion resistant probe is easily mounted and can handle high temperature and high pressure. The sensor is equipped with an interface adapter for compatibility with the DFRobot "Gravity" interface.

Note: Avoid placing the sensor near bright lights or in direct sunlight as these can cause interference.


  • Model: FS-IR02
  • Type: Photoelectric Liquid Level Sensor
  • Operating Voltage: 5V DC
  • Output Current: 12mA
  • Operating Temperature: - 25 ~ 105 ℃
  • Low Level Output: < 0.1 V
  • High Level Output: > 4.6 V
  • Liquid Level Detection Accuracy: ±0.5 mm
  • Material: Polycarbonate
  • Measuring Range: No limit
  • Life: 50,000 hours

Board Overview

Liquid Level Sensor-FS-IR02
Liquid Level Sensor-FS-IR02 Pin Mappings
Num. Name Description
1 (Red) GND Probe_GND
2 (Yellow) GND Probe_GND
3 (Blue) VCC Probe_VCC
4 (Whitel) OUT Signal Output
Liquid Level Sensor-FS-IR02 convert board
Liquid Level Sensor-FS-IR02 Pin Mapping
Num. Name Description
Left_1 GND Probe_GND
Left_2 GND Probe_GND
Left_3 VCC Probe_VCC
Left_4 IN Signal Input
Right_1 OUT Signal Output
Right_2 VCC VCC
Right_3 GND GND



SEN0205 Installation 1.jpg
SEN0205 Installation 2.jpg
SEN0205 Arduino connection.png


Sample Code

 1 /***************************************************
 2 * Liquid Level Sensor-FS-IR02 
 3 * ****************************************************
 4 * This example is to get liquid level
 6 * @author jackli(
 7 * @version  V1.0
 8 * @date  2016-1-30
10 * GNU Lesser General Public License.
11 * See <> for details.
12 * All above must be included in any redistribution
13 * ****************************************************/
14 int Liquid_level=0;
15 void setup() {
16  Serial.begin(9600);
17  pinMode(5,INPUT);
18 }
20 void loop() {
21 Liquid_level=digitalRead(5);
22 Serial.print("Liquid_level= ");Serial.println(Liquid_level,DEC);
23 delay(500);
24 }

Expected Results

When liquid comes in to contact with the sensor probe the microcontroller will output HIGH logic. When the liquid is not in contact with the probe the microcontroller will output LOW logic.


For any questions, advice or cool ideas to share, please visit DFRobot Forum.


SVG file

DFshopping car1.png Shopping from Gravity: Photoelectric Water / Liquid Level Sensor For Arduino or DFRobot Distributor.