LSLIDAR N401-P User manual

N401-P
User Manual
V5.0.1
2022.06
LeiShen Intelligent System Co., LTD
http://www.lslidar.com/

Safety Instruction
Before using the product, please read and follow the instructions of this manual
carefully, and refer to relevant national and international safety regulations.
∆Attention
Please do not disassemble or modify the Lidar privately. If you need special
instructions, please consult the technical support staff of LSLiDAR.
∆Laser Safety Level
The laser safety of this product meets the following standards:
● IEC 60825-1:2014
● 21 CFR 1040.10 and 1040.11 standards, except for the deviations (IEC 60825-
1, third edition) stated in the Laser Notice No. 56 issued on May 8, 2019. Please
do not look directly at the transmitting laser through magnifying devices (such
as microscope, head-mounted magnifying glass, or other forms of magnifying
glasses).
Eye Safety
The product design complies with Class 1 human eye safety standards. However,
to maximize self-protection, please avoid looking directly at running products.
∆Safety Warning
In any case, if the product is suspected to have malfunctioned or been damaged,
please stop using it immediately to avoid injury or further product damage.
Housing
The product contains high-speed rotating parts, please do not operate unless
the housing is fastened. Do not use a product with damaged housing in case of
irreparable losses. To avoid product performance degradation, please do not
touch the photomask with your hands.
Operation
This product is composed of metal and plastic, which contains precise circuit
electronic components and optical devices. Improper operations such as high
temperature, drop, puncture or squeeze may cause irreversible damage to the
product.
Power Supply
Please use the connecting cable and matching connectors provided by LeiShen

Intelligent to supply power. Using cables or adapters that are damaged or do not
meet the power supply requirements, or supply power in a humid environment
may cause abnormal operation, fire, personal injury, product damage, or other
property loss.
Light Interference
Some precise optical equipment may be interfered with by the laser emitted by
this product, please pay attention when using it.
Vibration
Please avoid product damage caused by strong vibration. If the product's
mechanical shock and vibration performance parameters are needed, please
contact LSLiDAR for technical support.
Radio Frequency Interference
The design, manufacture and test of this product comply with relevant
regulations on radiofrequency energy radiation, but the radiation from this
product may still cause other electronic equipment to malfunction.
Deflagration and Other Air Conditions
Do not use the product in any area with potentially explosive air, such as areas
where the air contains high concentrations of flammable chemicals, vapours or
particles (like fine grains, dust or metal powder). Do not expose the product to
the environment of high-concentration industrial chemicals, including near
evaporating liquefied gas (like helium), so as not to impair or damage the product
function.
Maintenance
Please do not disassemble the Lidar without permission. Disassembly of the
product may cause its waterproof performance to fail or personal injury.

Table of Contents
1Product Profile.......................................................................................................... 1
1.1 Overview ........................................................................................................ 1
1.2 Mechanism ..................................................................................................... 1
1.2.1 Time of Flight...................................................................................... 1
1.2.2 Grid Map Presentation...................................................................... 2
1.2.3 Reflector Positioning ......................................................................... 2
1.3 Specifications................................................................................................. 3
1.4 Connection..................................................................................................... 4
1.5 Interface Definition ...................................................................................... 5
1.5.1 LiDAR Base Connector ..................................................................... 5
1.5.2 Extension Cable.................................................................................. 6
1.5.3 Interface Box....................................................................................... 7
1.5.4 Interface Box Connection................................................................. 8
2Electrical Parameters............................................................................................. 10
3Communication Protocol...................................................................................... 12
4Optical Features ..................................................................................................... 13
4.1 Laser ..............................................................................................................13
4.2 Light Spot .....................................................................................................13
4.3 Optical Structure......................................................................................... 14
5Development tool and supports .........................................................................15
5.1 Point Cloud Display Software on Windows...........................................15
5.1.1 Software Interface Introduction.................................................... 15
5.1.2 Software Operation.........................................................................16
5.1.3 Software Interface Introduction.................................................... 16
5.2 Notes .............................................................................................................18
6ROS Driver Operation Under Linux OS.............................................................23
6.1 Hardware Connection and Test................................................................23
6.2 Software Operation Example ...................................................................24
7LiDAR Care.............................................................................................................. 26
7.1 Transportation .............................................................................................26
7.2 Installation.................................................................................................... 26
7.3 Cleaning ........................................................................................................ 26
Revision History ............................................................................................................27

List of Figures
Figure 1-1 Mechanism of N401-P....................................................................... 1
Figure 1-2 Demonstration of Ranging Function............................................... 2
Figure 1-3 Example of N401-P Grid Map Image.............................................. 2
Figure 1-4 Demonstration of Reflector Positioning......................................... 3
Figure 1-5 N401-P Mounting Dimension (unit: mm)....................................... 4
Figure 1-6 N401-P Mechnical Dimension (unit: mm)...................................... 5
Figure 1-7 Lidar Base Connector......................................................................... 6
Figure 1-8 Extension Cable................................................................................... 7
Figure 1-9 Interface Box........................................................................................ 8
Figure 1-10 Interface Box Connection ............................................................... 9
Figure 4-1 Light Spot Demonstration...............................................................13
Figure 4-2 Internal Optical Structure................................................................14
Figure 4-3 Lidar's Polar Coordinate................................................................... 14
Figure 5-1 Software Interface ............................................................................ 15
Figure 5-2 Software Operation Demonstration .............................................16
Figure 5-3 Data Packet Captured by Wireshark............................................. 19
Figure 5-4 Network Connection........................................................................20
Figure 5-5 IP Address and Subnet Mask Setting ............................................20
Figure 5-6 Windows Defender Firewall Setting ............................................. 21
Figure 6-1 ifconfig Command Feedback .......................................................... 23
Figure 6-2 sudo tcpdump -n -i eth0 Command Feedback............................24
Figure 6-3 ROS Program Running .....................................................................24

List of Tables
Table 1-1 Specifications of 20K-PRF Models.................................................... 3
Table 1-2 Interface Definition .............................................................................. 6
Table 1-3 Extension Cable Pin Definition .......................................................... 7
Table 1-4 Interface Box GPS Port Definition .................................................... 8
Table 2-1 Electrical Parameters..........................................................................10
Table 4-1 Laser Optical Parameters .................................................................. 13
Table 5-1 Lidar Menu Button Description ....................................................... 17
Table 5-2 Offline Menu Button Description ...................................................17
Table 5-3 Parameter Menu Button Description .............................................18

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1Product Profile
1.1 Overview
Based on TOF (time of flight), the N401-P series can two-dimensionally scan and
detect the environment across 360°. The lidar series uses wireless power supply
and wireless communication internally, and the pulse repetition frequency (PRF)
is 20KHz. The lidar reaches a measurement accuracy of ±3 cm with a maximum
range from 10m to 50m. With such high performance, the lidar mainly applies
to scenarios that require precise location and obstacle avoidance, including
indoor service robots, AGV, cleaning and sterilization robots, drones, and so on.
1.2 Mechanism
1.2.1 Time of Flight
Based on the TOF (time of flight) methodology, the N401-P series measures the
distance between a target object and the sensor, by calculating the difference
between the emission and return times of modulated laser. The laser emitter
sends out the modulated pulse laser, and an internal timer starts timing(t1). The
laser encounters the target object, part of the energy returns. When the lidar
receives the return laser signal, the timer will stop timing(t2). The formula for
distance between the lidar and the target object:
Distance = Speed of Light*(t2 – t1)/2
Figure 1-1 Mechanism of N401-P

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1.2.2 Grid Map Presentation
You can get the 2D grid map information of the surrounds across 360° within
the detecting distance, based on the combination of the distance value
calculated in real-time by the signal processing unit embedded in the N401-P
series and the angle information output by the highly accurate self-adjusted
angle measuring module.
Figure 1-2 Demonstration of Ranging Function
Figure 1-3 Example of N401-P Grid Map Image
*Note: The figures only demonstrate the function of the distance measuring
system. They are not proportional.
1.2.3 Reflector Positioning
When N401-P uses reflectors for positioning, the coordinates of reflectors are

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known, and the LiDAR gets the position opposite to the reflectors by scans so
that the position of the LiDAR can be converted to the coordinates in the
coordinate system where reflectors are located. In the figure below, A, B, and C
represent a reflector whose coordinates in the local coordinate system are
already known, and P denotes the LiDAR position. By scanning, you can get the
distances of P from A, B, and C, which are |PA|, |PB|, |PC|. Also, you can get the
values of ∠APB, ∠BPC according to the angle values of A, B, and C in the
LiDAR coordinate system. According to these values, the coordinates of LiDAR
P in the local coordinate system can be obtained. Therefore, the LiDAR is located
in real-time. If the positions of three positioning plates are measured
simultaneously for calculation, the positioning accuracy can reach millimeter
level.
Figure 1-4 Demonstration of Reflector Positioning
1.3 Specifications
Table 1-1 Specifications of 20K-PRF Models
Model
N401-P
scanning angle
360°
PRF
20KHz
Scanning Rate
20Hz/10Hz
Angular Resolution
0.36°: 20Hz
0.18°: 10Hz
Measurement
Accuracy
±3cm
Output Data
Resolution
Communication Protocol 1.6: 2mm;
Communication Protocol 1.7: 4mm
Wavelength
905nm
Detection Range
10m/20m/30m/40m/50m
Data Content
Azimuth, Distance, Intensity
Power Supply
9~32VDC (Recommended: 12/24VDC)
Operating
Temperature
-20℃~ 60℃
Noise
Starting-up: <60 dB, Operating:<50dB

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Motor
Brushless Motor
Communication
Interface
Fast Ethernet
Dimensions
Φ80*79.1mm
Weight
About 406g
1.4 Connection
The lidars of the N401-P series mainly are composed of laser emitting and
receiving modules, a signal processing module, a data/command transmission
interface, power module, etc. All N401-P lidars are externally powered by a
power supply of 9~32VDC (recommended: 12/24 VDC). You can use commands
to configure the lidar in terms of output model, scan frequency, scanning
frequency, angular resolution, and other parameters. Through the transmission
interface, you can directly interface with control boards such as
FPGA/DSP/ARM, so that commands and data can achieve fast and real-time
interaction. After the system is properly powered up, you can get the scanning
and ranging data of the lidar by calling the driver program of N401-P. Based on
the speed stabilization function of the N401-P lidar system, you can set the
scanning frequency by command, and the system automatically obtains the
speed information in real-time. The internal speed stabilization system will adjust
the torque according to the real-time speed, making the system work stably at
the set scanning frequency, with strong adaptability to changes in external
conditions such as temperature fluctuations, vibration, and altitude.
The mounting dimension and mechanical dimension are as follows:
Figure 1-5 N401-P Mounting Dimension (unit: mm)
via
LiDAR Mounting Hole

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Figure 1-6 N401-P Mechnical Dimension (unit: mm)
1.5 Interface Definition
The side of N401-P lidar base has an 8-pin aviation plug. You can use an
extension cable with a socket or an interface box to lead the function cable out.
1.5.1 LiDAR Base Connector
The external physical interface on the N401-P base is L102-M12-Z08A13, an
8-pin plug, to realize system power supply and data communication. The N401-
P series supports GPS.
Looking at the lidar interface L102-M12-Z08A13 from the direction as shown
by the below figure, you can see the connector.
Laser emission center
Laser reception
window

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Figure 1-7 Lidar Base Connector
Table 1-2 Interface Definition
Pin
Definition
Level
Description
1
VIN
9~32V
Power+
2
TD_N
-1~1V
Ethernet Data Stream
LiDAR → External Device
3
TD_P
-1~1V
Ethernet Data Stream
LiDAR → External Device
4
RD_N
-1~1V
Ethernet Data Stream
External Device → LiDAR
5
RD_P
-1~1V
Ethernet Data Stream
External Device → LiDAR
6
GPS_PPS
3.3/5V
GPS PPS/External Sync PPS(TTL)
7
GPS_Rec
-13 ~ 13V
GPS (latitude/longitude, hour/minute/second) (RS232)
8
GND
0V
Power-
1.5.2 Extension Cable
You must be careful not to hot plug or unplug the connecting cable. Otherwise,
it will cause irreversible damage. Before connecting, you should align the keys,
then insert it, and rotate the coat for fixing to ensure that it cannot be loosened
to ensure good contact. To separate it, you should reverse the operation which
means first rotating the coat to be loose and then pulling it out. Please do not
Key
slot
Contact Surface
(facing A)

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be forceful to avoid the deformation of terminals or even short circuits. If the
connector is damaged, please promptly contact technical support for a
replacement.
Figure 1-8 Extension Cable
Table 1-3 Extension Cable Pin Definition
S/N
Color and Specification
Definition
Description
1
Red (20AWG)
VCC
Power+
2
Light Blue (24AWG)
TD_N
Ethernet TX-
3
Blue (24AWG)
TD_P
Ethernet TX+
4
Light Orange (24AWG)
RD_N
Ethernet RX-
5
Orange (24AWG)
RD_P
Ethernet RX+
6
Yellow (20AWG)
GPS_PPS
GPS PPS/External Sync PPS
7
White (20AWG)
GPS_Rec
GPS(latitude/longitude,
hour/minute/second) (RS232)
8
Black (20AWG)
GND
Power-
1.5.3 Interface Box
An interface box is sent to you with the Lidar to facilitate the testing and
connection. Please note that the interface box is not a necessary accessory for
Lidar operation. The interface box includes a 5.5*2.1mm DC socket, an indicator
light, an RJ45 network connector, and a 6-pin GPS port.

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Figure 1-9 Interface Box
The GPS port of the interface box is the SM06B-SRSS-TB presented by JST, and
the recommended plug interface for the external GPS module is SHR-06V-S-B
presented by JST.
Table 1-4 Interface Box GPS Port Definition
S/N
Definition
I/O
Description
1
PPS Sync Signal
I
TTL level range from 3.3V to 12V; its cycle is 1
second, and the recommended pulse width is more
than 5 ms
2
GPS Power Supply 5V
O
No hot plug or unplug
3
GPS_GND
O
Good contact
4
GPS
(latitude/longitude,
hour/minute/second)
I
RS232 level, baud rate 9600 bps
5
GPS_GND
O
Good contact
6
NC
-
-
1.5.4 Interface Box Connection
Note: Make sure the lidar is powered down when plugging or unplugging the
GPS module from the GPS port of the interface box, or when connecting or
disconnecting the signal from the GPS pin of the cable. If it is necessary to plug
or unplug the interface box in the power-on state, please first release static
electricity and avoid direct hand contact with the GPS interface or pins.

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Figure 1-10 Interface Box Connection

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2Electrical Parameters
The N401-P series communicate with Fast Ethernet. An N401-P lidar is made of
a high frequency ranging core, a wireless transmission system, and a rotating
subsystem. The rotating subsystem is driven by a brushless DC motor spinning
inside the system. The signal cable of N401-P can be connected to
FPGA/DSP/ARM/SCM via Ethernet. You connect an external system and the
lidar and follow the communication protocol of the lidar system to obtain the
scanned point cloud data, device information and status, and set the working
mode in real-time. The lidar does not have a power switch. Therefore, once
powered on, the lidar will start and transmit data according to the factory default
parameters.
Table 2-1 Electrical Parameters
Item
Minimum
Recommended
Maximum
Note
Power
Supply
Voltage
9V
12V/24V
32V
The power supply not in the
range may lead to inaccurate
ranging or irreversible
damage. The output of
external power supply should
be at least 10W. You should
not use power supplies below
9V or above 32V in a long
term.
Voltage
Ripple
-
-
80MV
Too much ripple can cause
irreversible damage to the
hardware. Therefore, the
smaller the ripple, the better.
Operating
Current
-
320mA/12V
400mA/12V
GPS PPS
3V
-
13V
Its cycle is 1 second, and the
recommended pulse width is
more than 5 ms
GPS REC
-13V
-
13V
RS232 level, baud rate 9600
bps
Note: If due to unavoidable factors, the cable needs to supply power over a long
distance, you should consider the undervoltage situation resulting from the line
loss caused by the cable. To solve the problem, it is required to raise the voltage
at the supply end to meet the supply voltage demand. For a 5m cable, the power
supply voltage should be more than 19V. If the cable is longer than 10m, the
voltage should be 24V.
For many situations where the lidar is powered by a battery, although the lidar
adopts certain anti-surge measures inside, the solutions should be different from
case to case. In some harsh situations, you should take some external anti-surge

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measures. Or you can use the interface box presented by LSLiDAR, which has
been improved inside in terms of the problem.

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3Communication Protocol
When the N401-P is working, each set of data is output through the
communication interface. The output data has uniform message formats. If you
need the detailed communication protocol, N401-P LiDAR Communication
Protocol V1.6, or N401-P LiDAR Communication Protocol V1.7, please contact
LSLiDAR support.

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4Optical Features
4.1 Laser
Dependent on a 905nm laser, N401-P emits high-frequency pulsed lasers
through the optical assembly, receives the laser signal through the optical
assembly, and completes the photoelectric conversion by the receiver board.
The distance value calculation is completed by the master control chip and the
laser optical parameters are as follows:
Table 4-1 Laser Optical Parameters
Item
Minimum
Recommended
Maximum
Note
Wavelength
895nm
905nm
915nm
-
Peak Power
-
25W
-
-
Average Power
-
0.8mW
-
-
FDA
Class I
IEC 60825-1:2014
4.2 Light Spot
The light spot of N401 lidar is a vertical oval. Its vertical divergence angle is
6.8mrad, and the horizontal divergence angle is 2.5mrad. The spot size at any
distance can be calculated by multiplying the divergence angle by the distance.
For example, the calculation of a spot at 10m is as follows
Vertical direction at 10m: 10*6.8*10-3=0.068m
Horizontal direction at 10m: 10*2.5*10-3=0.025m
Figure 4-1 Light Spot Demonstration

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4.3 Optical Structure
The N401-P series uses a telescopic optical structure with the receiver and
transmitter placed horizontally side by side. When designing the lidar installation
and robot system integration, it is necessary to focus on the internal optical
structure of the LIDAR so that the effective detection angle of the LIDAR can
be designed accurately. To facilitate your use, especially in terms of the
calculation of geometric relationships, LSLiDAR defines a polar coordinate
system with the center point of the lidar as the pole, clockwise as positive, and
the outlet direction as the zero-degree angle.
The internal optical structure (unit: mm) and the polar coordinates of the N401-
P series as shown in the figure below (top view):
Figure 4-2 Internal Optical Structure
Figure 4-3 Lidar's Polar Coordinate