4m Laser Range Sensor

SKU: SEN0491

This 4m laser range sensor detects objects in 4~400cm with ±2cm accuracy. It supports 3 measurement modes, suitable for security gates, access control, alarms, smart trash cans, and smart cars/robots for obstacle avoidance. With a waterproof, shockproof design (threaded barrel + optical cover), it filters optical interference. Using invisible laser and a voltage regulator, it offers stable performance, UART output, and an alarm line (triggers Low when distance < user-set threshold). Note: Data is unstable when measuring black objects.

Front of laser distance sensor UART cable with colored wires and circular connector-DFRobot product sku:SEN0491 image.

Downloadable Resources

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  • Tech Specs
  • Specification

    Parameter Value
    Power Supply Voltage 6-36V
    Measuring Distance 4-400cm
    Measurement Accuracy ±2cm
    Launch Angle 39.6°
    Receiving Angle 36.5°
    Working Current <38mA
    Communication Interface UART
    Waterproof Rating IP67
    Baud Rate 2400-921600 optional 115200 (default)
    Frequency 20Hz (default)
    Working Temperature -20~70°C
    Size 21.5x21x8 mm / 0.85×0.83×0.31 inch

    Pinout

    Label Name Description
    Red VCC 6-36V power supply
    Green RX UART receiving data line
    Yellow TX UART transmitting data line line
    Black GND Power ground
    White ALARM Police connection line

    FAQ

    • What is the communication protocol for this sensor?

      The sensor adopts the industry standard Modbus protocol, the specific read and write format is as follows: Modbus communication, the command number is divided into two types, read command and write command, 0x03 (read command) reads the corresponding register data, 0x06 (write command) write data to the corresponding register.

      Host sending frame (HEX)

      The module address is 0x50 (default), the read command is 0x03, the register 0x34 (measurement distance), and the length is one bit. Command: 50 03 00 34 00 01 C8 45 Slave response frame (HEX)


      The module address is 0x50, the read command is 0x03, and the length is 2 bits. Example: Read the measured distance Send command: 50 03 00 34 00 01 c8 45 Receive data: 50 03 02 07 0B 06 7F

      Data analysis: 0x50 is Modbus address, 0x03 read command, 0x02 data length, 0x07 0x0B measurement data corresponding to 0x070B is decimal 1803, measurement distance is 1803mm, 0x06 0x7F is CRC check bit.

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