serial-laser-ranger 0.1.3

Python library for serial laser distance measurement modules

serial-laser-ranger

Python library for serial laser distance measurement modules.

Works with generic laser ranging modules commonly found on AliExpress, as well as compatible units like the DFRobot SEN0366. These modules communicate via serial (UART) at 9600 baud.

Specifications

Parameter	Value
Operating Voltage	DC 3.3V - 5V
Measuring Range	Indoor: 0.05 - 50m, Outdoor: 0.05 - 80m
Accuracy	±1.0mm (standard deviation)
Laser Type	620 - 690nm, Class II (<1mW)
Laser Spot	6mm @ 10m, 30mm @ 50m
Measurement Time	0.05 - 1s
Operating Temperature	-10°C to +60°C
Dimensions	48 × 42 × 18mm
Weight	~60g
Protection	IP40

Note: Performance may degrade in strong ambient light, extreme temperatures, or with poorly reflective surfaces.

Real-World Limitations

Despite marketing claims of 1-20Hz measurement rates, the actual maximum is ~4 Hz (~235ms per measurement). This is a hardware limitation:

• The set_frequency() method has no observable effect on measurement speed
• The set_data_return_interval() only adds delay between measurements; it cannot speed them up
• Maximum continuous rate is achieved with interval set to 0

Motion constraints: If the target distance changes faster than ~25 cm/s (0.25 m/s), the sensor will reset and return errors. This limits use for tracking fast-moving objects.

Installation

pip install serial-laser-ranger

Quick Start

from serial_laser_ranger import LaserRanger

with LaserRanger("/dev/ttyUSB0") as ranger:
    distance = ranger.measure_single()
    print(f"{distance:.3f} m")

Or even simpler:

from serial_laser_ranger import measure

print(f"{measure('/dev/ttyUSB0'):.3f} m")

Features

• Single and continuous measurement modes
• Laser on/off control
• Configurable resolution (1mm or 0.1mm)
• Configurable range (5m to 80m)
• Adjustable measurement frequency
• Distance offset calibration
• Error handling with descriptive messages

Usage

Basic Measurement

from serial_laser_ranger import LaserRanger

with LaserRanger("/dev/ttyUSB0") as ranger:
    distance = ranger.measure_single()
    print(f"Distance: {distance:.3f} m")

Continuous Measurement

with LaserRanger("/dev/ttyUSB0") as ranger:
    # Take 10 measurements
    for distance in ranger.measure_continuous(count=10):
        print(f"{distance:.3f} m")

    # Or run indefinitely (Ctrl+C to stop)
    for distance in ranger.measure_continuous():
        print(f"{distance:.3f} m")

With Callback

def on_measurement(distance):
    print(f"Distance: {distance:.3f} m")

with LaserRanger("/dev/ttyUSB0") as ranger:
    for _ in ranger.measure_continuous(callback=on_measurement, count=100):
        pass

Configuration

with LaserRanger("/dev/ttyUSB0") as ranger:
    # Set 0.1mm resolution
    ranger.set_resolution(LaserRanger.RESOLUTION_01MM)

    # Set 30m range
    ranger.set_range(LaserRanger.RANGE_30M)

    # Set 20 Hz measurement frequency
    ranger.set_frequency(20)

    # Apply distance offset (e.g., for mounting offset)
    ranger.set_distance_offset(50)  # +50mm offset

Laser Control

with LaserRanger("/dev/ttyUSB0") as ranger:
    ranger.laser_on()   # Turn laser on
    ranger.laser_off()  # Turn laser off

Error Handling

from serial_laser_ranger import LaserRanger, LaserRangerError

with LaserRanger("/dev/ttyUSB0") as ranger:
    try:
        distance = ranger.measure_single()
    except LaserRangerError as e:
        print(f"Error {e.code}: {e.message}")

Error codes:

• ERR-1e: Low power
• ERR-14: Calculation error
• ERR-15: Laser low power
• ERR-18: Weak signal or measurement time too long
• ERR-20: Strong ambient light
• ERR-74: Out of range

API Reference

LaserRanger

Constructor

LaserRanger(
    port="/dev/ttyUSB0",  # Serial port
    baudrate=9600,         # Baud rate (default 9600)
    timeout=2.0,           # Read timeout in seconds
    address=0x80           # Device address (default 128)
)

Methods

Method	Description
measure_single()	Take a single measurement, returns distance in meters
measure_continuous(callback=None, count=0)	Generator yielding continuous measurements
laser_on()	Turn the laser on
laser_off()	Turn the laser off
set_resolution(resolution)	Set measurement resolution
set_range(range_m)	Set measurement range
set_frequency(freq)	Set measurement frequency (Hz)
set_distance_offset(offset_mm, negative=False)	Set distance offset
set_start_point(from_top)	Set measurement reference point
set_power_on_start(enabled)	Enable/disable auto-start on power

Constants

Constant	Value	Description
RESOLUTION_1MM	0x01	1mm resolution
RESOLUTION_01MM	0x02	0.1mm resolution
RANGE_5M	0x05	5 meter range
RANGE_10M	0x0A	10 meter range
RANGE_30M	0x12	30 meter range
RANGE_50M	0x32	50 meter range
RANGE_80M	0x50	80 meter range

Hardware

Wiring

Module Pin	Connection
VCC	5V
GND	Ground
TX	RX on USB-Serial adapter
RX	TX on USB-Serial adapter

Serial Settings

• Baud rate: 9600
• Data bits: 8
• Stop bits: 1
• Parity: None

Examples

See examples.py for practical examples including:

• Basic measurement
• Statistics collection
• Real-time monitoring
• CSV logging
• Motion detection
• Calibration checking

Run examples with:

python examples.py basic
python examples.py statistics
python examples.py monitor

Applications

• UAV automatic landing
• Robotics distance sensing
• Industrial level monitoring
• Electronic measurement tools
• Security systems

References

• DFRobot SEN0366 Wiki - Detailed documentation and specifications
• Electromaker Product Page - Additional product information

License

MIT License