Meskernel LDJ100-689 Laser Distance Sensor

Revision Records

Version	Date	Revision Personnel	Revised Contents
R0	2021/8/30	ly	First Edition
R1	2024/3/28	hqx	1. Optimized the description of product performance parameters
			2. Optimized the operating instruction of multi modules communication
			3. Improved the module function description
			4. Add a list of instruction references
			5. Add a quick testing guide tutorial

Principle of Measurement

At present, the optical time-of-flight measurement methods used in laser ranging mainly include: direct Time of Flight measurement (dToF) and indirect Time of Flight measurement (iToF).
The dToF is a direct measurement of the time difference between the transmitting laser and receiving laser, and an inverse calculation of the distance of laser travel according to the speed of light. Based on the speed of light, this method requires the circuit related to the measurement of optical time of flight to have a very high reaction speed to improve the resolution of the measurement of time of flight, so as to improve the final ranging distance resolution. In view of the current technical level of the device, its distance division rate can be centimeters.
The iToF usually refers to the method of indirectly measuring the time of flight of light by modulating the emitted laser and analyzing the change of the relevant characteristics of the modulated laser after the propagation of a certain distance. This method is most commonly used for the analysis of the phase characteristics of the modulated laser.
Compared with the dToF, the iToF greatly reduces the requirements for hardware processing speed, is easy to implement and has a higher distance division rate, which can currently reach the millimeter or even micron level. However, due to the need to analyze the modulation information of the laser, the measurement speed of iToF is much lower than that of dToF.
This product uses the iToF is much more precisely, the use of phase difference laser ranging method, which is usually suitable for short and medium-range ranging, measuring accuracy up to millimeters or even micron level. The basic principle of the phase difference laser ranging method is to modulate the emitted laser at a specified frequency, and illuminate the modulated laser to the measured object, and then reflect back to the receiver by the measured object. The phase information carried by the transmitted modulated laser and the modulated laser received after reflection will be different, and the phase difference can be calculated by analyzing the phase of the transmit-ted and the received phase. The actual propagation distance of the laser can be calculated by combining the phase difference information and the specified modulation frequency. Figure 1-1 shows the basic schematic diagram：
The measured distance can be expressed as: 2L=Δφ×c×T/2π

In the formula, L represents the measurement distance, c represents the speed of light propaga-tion in the air, and T represents the period of the modulation signal, Δφ The phase difference between emitting modulated light and receiving modulated light.
Phase-based laser ranging has the advantages of high ranging accuracy, wide measurement range, and strong anti-interference ability, and is therefore widely used in industries, surveying, remote sensing, and other fields.

Structure Diagram

 

Figure 2-2 Modu e Structure D means ona D gram

Product Parameters

Table 3-1 Product Parameters Table

Type	Parameter Name	Parameter Value
Product Performance	Measurement Range	0.03m~100m/150m/200m (Reflectivity: 1.0, interference light intensity: 3kLux)
	Measurement Unit	mm
	Measurement Time	0.05~4 seconds (Reflectivity: 1.0, interference light intensity: 1kLux)
	Accuracy	±(3mm+D*(1/10000)) (Reflectivity: 0.2-1.0, interference light intensity: 1kLux)
	Measurement Resolution	1mm
	Continuous Mea- surement Frequency	20Hz (Reflectivity: 1.0, interference light intensity: 1kLux, Distance：0.03m-10m)
Optical Parameters	Reflectivity Range	0.02~1.0
	Laser Class	CLASS-II, according to IEC 60825-1
	Laser Power	<1mW
	Laser Wavelength	λ=610nm~690nm
	Spot Diameter	<8mm@10m <20mm@20m <40mm@40m
	Spot Dispersion Range	Spread target circle diameter< 100mm@10m Target Spread target circle diameter< 200mm@20m Target Spread target circle diameter< 300mm@30m Target
Electrical Parameters	Power Supply Voltage	DC: 2.5~3.6V; Recommendation: 3.3V
	Current	Shutdown leakage current		< 10µA @ 3.3V
		Standby current		< 80mA@3.3V
		Turn on laser		< 120mA@3.3V
		Continuous measurement mode		< 160mA@3.3V
Communication Characteristics	Baud Rate Version	Automatic Baud Rate	The default baud rate is 115200bps, and the baud rate can be set to (9600~115200bps)
		Fixed Baud Rate	The default baud rate is 115200bps, customization (4800bps, 9600bps, 19200bps, 38400bps, 115200bps)
	Communication Level	TTL(3.3V)
	Supporting Interfaces	USART; RS232/RS485 (External level transfer module required)
Other	Size	62.91mmx40.00mmx18.00mm (Length x width x height)
	Weight	14g ± 1.4g
	Working Temperature	0~40℃ (32~104℉)
	Storage Temperature	-25~60℃ (-13~140℉)

• Under poor measurement conditions, the range will decrease and the error will increase, such as strong ambient light, large or small diffuse reflection coefficient of the measured point;
• A wider working temperature range can be customized;
• Higher working frequency can be customized

The following table is a common table of object reflectivity parameters, which can be used to measure whether the module meets the requirements based on the following parameters

Table 3-2 Material Reflectivity Reference Table

NO.	Material Name	Reflectivity
1	Black velvet	0.5%
2	Black paper	1~2%
3	Dark green leaves	1~10%
4	Pure water	2%
5	Black cloth	3%
6	Asphalt	4%
7	Brown walls	6%
8	Shady sands & rocks	6~10%
9	Quartz glass	8%
10	Black cardboard	10%
11	Mud wall	10%
12	Black paint	10~15%
13	Brown wood	12%
14	Tile	15%
15	Bright green leaves	15~20%
16	Bright sands & rocks	18~24%
17	Clean rough board	20%
18	Red brick	20%
19	Young leaves	20~25%
20	Grey paint	20~30%
21	Grey concrete	25%
22	Cedar board painted with yellow lacquer	40%
23	Cedar board surface (real color)	45%
24	White polyethylene plastic	60%
25	White wall	60%
26	White paint	60%
27	Pure white felt	60~70%
28	White paper	60~75%
29	White enamel	70%
30	The surface of newly fallen snow	70~74%
31	White latex paint	80%
32	Pure white cloth	80~85%
33	Grinding surface of glass	85%
34	Gypsum	87%
35	White cardboard	90%
36	Grinding surface of silver	92%
37	Kodak standard whiteboard	100%

Pins and Electrical Parameters

Pin Layout

Note: The typical value of VCC in the figure is 3.3V.

Pin Definition

Table 4-1 Pin Definition

No.	Name	Function	Default Level	Explanation
1	TXD	Digital Output	High	Module serial port sending pin, defaults to open drain
2	RXD	Digital Input	High	Module serial port receiving pin, defaults to open drain
3	VCC	Power Input	Power decision	Typical module input power requirements: > 300mA@DC: 3.3V
4	VCC	Power Input	Power decision	Typical module input power requirements: > 300mA@DC: 3.3V
5	PWREN	Digital Input	Low	Module power-enable pin, triggered by high-level signal, VIH=2.0V, VIL=0.5V
6	GND	Ground Wire	Ground wire decision	Module power supply grounding

Note:

When the input level value of PWREN is higher than the value of VIH, it is considered that PWREN has been input at a high level;

When the input level value of PWREN is lower than the VIL value, it is considered that PWREN has been input at a low level. To ensure reliable opening or closing of the module, please pay attention to the initial level and control level of the PWREN pin.

Voltage Limit Value

Table 4-2 Voltage Limit Value

Parameter	Minimum Value	Maximum Value
PWREN	-0.3V	4.0V
TXD	-0.3V	VCC+0.3V
RXD	-0.3V	VCC+0.3V
VCC	-0.3V	4.0V
GND	0	0

Module Connection

Multi-module connection

Note:

The number of modules in a single network segment should not exceed 8, and the maximum number of modules in multiple network segments should not exceed 127. The pull-up resistance value of the bus should be adjusted appropriately based on the number of modules connected to the bus

(the pull-up resistance value can be reduced appropriately when connecting multiple modules)

Connect or Selection

Soldering

Users can choose appropriate connecting wires to solder to the corresponding soldering points of the module, as shown in Figure 5-2:

Status Code

Tab e 6-1 Exp anat on of Modu e Return ng Its Status Code Informat on

Status Code	Description	Measures
0x0000	No errors	–
0x0001	The input voltage is low, and the input voltage value should be ≥ 2.0V	Check input battery voltage, change battery
0x0002	Network error, can be ignored	–
0x0003	Module temperature is low (<-20℃)	Increase module temperature
0x0004	Module temperature is high (>+60℃)	Reduce module temperature
0x0005	Target out of range	Use within the measurement range specified in the module manual
0x0006	Invalid measurement value	Remeasure
0x0007	Excessive ambient light	Reduce the light intensity of the measurement environment
0x0008	Weak laser signal	Whether there is contamination on the output lens or enhancing the reflectivity of the mea- surement target
0x0009	Strong laser signal	Reduce the reflectivity of the measurement target
0x000A	Hardware error1	Ask customer service based on the error code
0x000F	Laser signal instability	Stabilize the body or check if the power supply is stable
0x0081	Invalid communication format	Check if the command was sent incorrectly

Fault Handling

1. After connecting the computer to the USB-TTL convert module, the computer did not find any serial devices.
2. Check if the computer has the CH340 driver If not, you can find the “CH340 driver” application in the measurement data kit and install it;
3. Check if the communication interface connection between the USB-TTL module and the computer is stable;\
4. Check if the computer USB port is damaged or if the USB to TTL module is damaged
5. After the module is successfully powered on and connected to the computer, the module does not respond when sending commands.
6. Check if the TXD and RXD pins of the module are connected reversely;
7. Check if the baud rate is set correctly;
8. Check if the TXD and RXD pins are in open drain output If they are in open drain output mode, check if a pull-up resistor is connected;
9. The module is able to communicate normally, but the received data shows garbled
   1. Check if the serial debugging assistant is set to HEX display (hexadecimal display);
   2. Check communication stability:
   3. Mainly check if there is electromagnetic interference or other signal interference nearby, and if so, try to stay as far away as
   4. Check if the serial communication line is too If it is a regular USART (TTL level) com- munication, the cable should not exceed one meter as much as possible.

Instruction Reference List

Tab e 8-1 The Descr pt on of the Modu e Instruct on

Function	Sending Instructions/Receiving Data	Explanation
Check Module Status	TX:AA 80 00 00 80	Read the current status of the module
	RX:AA 80 00 00 00 01 00 00 81	Read there is no error in the module
Check Module Hardware Version	TX:AA 80 00 0A 8A	Read the current hardware version of the module
	RX:AA 80 00 0A 00 01 BB 2D 73	Read the current hardware version as 0xBB2D
Check Module Software Version	TX:AA 80 00 0C 8C	Read the current hardware version as
	RX:AA 80 00 0C 00 01 43 09 D9	Read the current software version as 0x4309 the module
Check Module Serial Number	TX:AA 80 00 0E 8E	Read the current serial number version of the module
	RX:AA 80 00 0E 00 02 A2 3B BC 97 C0	Read the current module serial number version as 0xA23BBC97
Check Module Input Voltage	TX:AA 80 00 06 86	Read the current input voltage of the module
	RX:AA 80 00 06 00 01 32 19 52	Read the current module input voltage as 3219mV
Read the Result of the Last Measurement	TX:AA 80 00 22 A2	Read the result of the last measurement
	RX:AA 80 00 22 00 03 00 00 00 32 00 2C 03	Read the last measurement result of the current module as 0x00000032(50mm)
Set Module Address	TX:AA 00 00 10 00 01 00 05 16	Set module address (change the module address from 0x00 to (0x05)
	RX:AA 00 00 10 00 01 00 05 16	Successfully set module address to 0x05
Set Module Offset	TX:AA 00 00 12 00 01 00 79 8C	Set the module offset to 0x79(121mm)
	RX:AA 00 00 12 00 01 00 79 8C	Offset set successfully
Module On/Off Laser	TX:AA 00 01 BE 00 01 00 01 C1	Turn on laser
	RX:AA 00 01 BE 00 01 00 01 C1	Laser turned on
	TX:AA 00 01 BE 00 01 00 00 C0	Turn off laser
	RX:AA 00 01 BE 00 01 00 00 C0	Laser turned off
Single Automatic Measure	TX:AA 00 00 20 00 01 00 00 21	Enable single automatic measurement
	RX:AA 00 00 22 00 03 00 00 00 33 00 2F 87	Return measurement data as 0x00000033(51mm), The signal quality is 0x002F
Single Low Speed Measure	TX:AA 00 00 20 00 01 00 01 22	Enable single low-speed measurement
	RX:AA 00 00 22 00 03 00 00 00 32 00 31 88	Return measurement data as 0x00000032(50mm), The signal quality is 0x0031
Single Quick Measure	TX:AA 00 00 20 00 01 00 02 23	Enable single quick measurement
	RX:AA 00 00 22 00 03 00 00 00 32 00 33 8A	Return measurement data as 0x00000032(50mm), The signal quality is 0x0033
Continuous Automatic Measure	TX:AA 00 00 20 00 01 00 04 25	Enable continuous automatic measurement
	RX:AA 00 00 22 00 03 00 00 00 33 00 3C 94	Return measurement data as 0x00000033(51mm), The signal quality is 0x003C
Continuous Low Speed Measure	TX:AA 00 00 20 00 01 00 05 26	Enable continuous low-speed measurement
	RX:AA 00 00 22 00 03 00 00 00 33 00 3C 94	Return measurement data as 0x00000033(51mm), The signal quality is 0x003C
Continuous Fast Measure	TX:AA 00 00 20 00 01 00 06 27	Enable continuous rapid measurement
	RX:AA 00 00 22 00 03 00 00 00 32 00 38 8F	Return measurement data as 0x00000032(50mm), The signal quality is 0x0038

Operation Protocol

USART interface 

Module with automatic baud rate: 9600bps, 19200bps, 38400bps, 115200bps; Module with fixed baud rate: 115200bps, can be customized (4800bps / 9600bps / 19200bps / 38400bps / 115200bps);

• Start bit: 1 bit
• Data bits: 8 bits
• Stop bit: 1 bit
• Parity bit: None
• Serial port flow control: None

For modules supporting automatic baud rate, if the module does not receive the automatic baud rate handshake byte 0x55 within 2.5 seconds after power-on, or if it receives an incorrect hand- shake byte, the module will communicate at a fixed rate of 115200bps.

Control Flowchart

All communication commands are sent by the host, and the laser ranging module as a guest to respond to the host’s commands. The commands timeline is shown in Figure 10-1:

Module with automatic baud rate

In the initial state, the guest (laser ranging module) is in a powered-off mode before the host pulls its PWREN pin high. Once the PWREN pin is pulled high, if the guest supports automatic baud rate detection, it will perform a self-check after approximately 100ms and then enter the automatic baud rate handshake phase. At this point, the host sends the handshake byte (0x55) to the guest at the required baud rate. If communication is successful, the guest responds to the host with a single byte of data, which represents the guest’s communication address (1 byte of data). In a scenario with one host and multiple guests, after the host sends the handshake byte, it may receive self-address responses from multiple guests, which could lead to USART bus conflicts. In such cases, these bytes should be ignored.

After the automatic baud rate is successfully set, communication between the host and guest has been successfully established.

Measurement Model

 Singe Measurement

Send a single measurement command and return a measurement result after successful measurement.

on tenuous Measurement

Send a continuous measurement command, and the module remains in continuous measurement mode. For each successful measurement, the measurement result will be returned. To exit continuous measurement, the host needs to send 1 byte of 0x58 (Capital ‘X’ in ASCII) during the measurement period.

Working Mode

• Automatic mode: The module automatically selects the measurement speed based on the reflected signal strength or signal The smaller the signal quality (SQ) value, the more reliable the measurement result, or the higher the signal strength, the more reliable the measurement result.
• Low-speed mode: prioritized module measurement accuracy
• High-speed mode: prioritizes module measurement speed

Table 12-1 Mode Funct on the diagram for Combining Measurement Mode and Working Mode

Control Command Framework

By sending different commands through the computer, the corresponding functions of the module can be used or the corresponding status information of the module can be obtained.

Tab e 13-1 Commun cat on Format Descr pt on

Control Register

There are many registers inside the module, and users can perform basic operations on the module by controlling the module registers.

Tab e 14-1 Summary and Descr pt on of Modu e Contro Reg sters

No.	Register	Name	Effect
1	0X0000	REG_ERR_CODE	System status code
2	0X0006	REG_BAT_VLTG	Input voltage
3	0X0010	REG_ADDRESS	Module address
4	0X0012	REG_OFFSET	Measurement result offset
5	0X0020	REG_MEA_START	Initial measurement
6	0X0022	REG_MEA_RESULT	Measurement result
7	0X01BE	REG_CTRL_LD	Laser diode control

Control Command

The following tables provide a detailed description and summary of the commands for the control module.

Read the Status of the Laser Module

The module status code is used to indicate whether the module currently has software or hardware issues, and users can get the status code of issue through this command, if there is no issue, the status code is 0x0000.

Byte	0	1	2	3	4
Name	First byte	Read and write direction indica- tor bit / Current guest address	Register address		Checksum
Data	0xAA	0x80	0x00	0x00	0x80

• Command type: read command Guest address: 0x00
• Register address: 0x0000
• Command description: after the previous command is executed, the host sends this command to
• read the current status code of the module guest feedback:

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read and write direction indica- tor bit/Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x80	0x00	0x00	0x00	0x01	0xYY	0xZZ	Checksum

• Module status: 0xYYZZ

Read the Hardware Vers on

Byte	0	1	2	3	4
Name	First byte	Read and write direction indica- tor bit / Current guest address	Register address		Checksum
Data	0xAA	0x80	0x00	0x0A	0x8A

• Command type: read command Guest address: 0x00
• Register address: 0x000A
• Command description: after the previous command is executed, the host sends this command to
• read the hardware version of the module
• Guest feedback

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read/write direction indicator bit/current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x80	0x00	0x0A	0x00	0x01	0xVV	0xYY	Checksum

• Hardware version number: 0xVVYY

Read the Software Vers on

Byte	0	1	2	3	4
Name	First byte	Read and write direction indica- tor bit/Current guest address	Register address		Checksum
Data	0xAA	0x80	0x00	0x0C	0x8C

• Type: read command Guest address: 0x00 Register address: 0x000C
• Command description: after the previous command is executed, the host sends this command to
• read the software version of the module
• Guest feedback

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read and write direction indica- tor bit/Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x80	0x00	0x0C	0x00	0x01	0xVV	0xYY	Checksum

Software version: 0xVVYY

Read the Module Sera Number

Byte	0	1	2	3	4
Name	First byte	Read and write direction indica- tor bit / Current guest address	Register address		Checksum
Data	0xAA	0x80	0x00	0x0E	0x8E

• Type: read command Guest address: 0x00 Register address: 0x000E
• Command description: after the previous command is executed, the host sends this command to
• read the module serial number
• Guest feedback:

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read and write direction indicia- tor bit/Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x80	0x00	0x0E	0x00	0x01	0xSS	0xNN	Checksum

Module serial number: 0xSSNN

Read the input Voltage

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read and write direction indica- tor bit/Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x80	0x00	0x06	0x00	0x01	0x32	0x19	Checksum

Input voltage: 3219 mV

Read the current Offset

Byte	0	1	2	3	4
Name	First byte	Read & Write direction indicator bit / Current guest address	Register address		Checksum
Data	0xAA	0x80	0x00	0x12	0x92

• Type: Read Command Guest address: 0x00 Register address: 0x0012
• Command Description: After the previous command is executed, the host reads the measurement
• results.
• Guest Feedback:

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read & Write direction indica- tor bit / Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x00	0x00	0x12	0x00	0x01	0xVV	0xYY	Checksum

Module offset: 0xVVYY

Read the Measurement Results

Byte	0	1	2	3	4
Name	First byte	Read/write direction indicator bit/current guest address	Register address		Checksum
Data	0xAA	0x80	0x00	0x22	0xA2

• Type: Read Command
• Guest Address: 0x00
• Register Address: 0x0022
• Command Description: After the previous command is executed, the host reads the offset result.
• Guest Feedback:

Byte	0	1	2	3	4	5	6:9	10:11	12
Name	First byte	Read & Write direction indicator bit / Current guest address	Register address		Number of valid data		Valid data	Signal Quality	Checksum
Data	0xAA	0x00	0x00	0x22	0x00	0x03	0xAABBCCDD	0x0101	Checksum

Set the Module Address

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read & Write direction indicator bit / Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x00	0x00	0x10	0x00	0x01	0x00	0xYY	Checksum

• Type: Write Command Guest Address: 0x00 Register Address: 0x0010
• Command Description: After the previous command is executed, the host sets the guest address
• which is then saved in case of a power cut.
• Guest Feedback

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read & Write direction indica- tor bit / Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x00	0x00	0x10	0x00	0x01	0x00	0xYY	Checksum

Set the guest address to 0xYY (The address will only take bits [6:0], other bits will be ignored); Note: Do not set the guest address to broadcast address 0x7F, which is reserved for one host to multiple guest networks. It requires all guests to measure the distance simultaneously and will not be measured until the host requires one guest to measure

Setting the Modue Offset

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read & Write direction indica- tor bit / Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x00	0x00	0x12	0x00	0x01	0xZZ	0xYY	Checksum

• Type: Write Command Guest address: 0x00 Register address: 0x0012
• Command Description: After the previous command is executed, the host sets the guest offset,
• which represents the current ranging starting point and defaults to 0.
• For example, if the offset 0xZZYY=0x007B (+123), the final measured value will be increased by 123mm; If the offset 0xZZYY=0xFF85 (-123), the final measured value will be subtracted by 123mm. Guest feedback

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read & Write direction indica- tor bit / Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x00	0x00	0x12	0x00	0x01	0xZZ	0xYY	Checksum

Turn On/Off the Laser

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read & Write direction indica- tor bit / Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x00	0x01	0xBE	0x00	0x01	0x00	0xZZ	Checksum

• Type: Write Command Guest Address: 0x00 Register Address: 0x01BE
• Command Description: After the previous command is executed, turn on/off the laser.
• Laser On: 0xZZ=0x01 / Laser Off: 0xZZ=0x00
• Guest Feedback:

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read & Write direction indica- tor bit / Current guest address	Register address		Number of valid data		Valid data		Checksum

Data

0xAA

0x00

0x01

0xBE

0x00

0x01

0x00

0xZZ

Checksum

Singe Automat Measurement

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read & Write direction indica- tor bit / Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x00	0x00	0x20	0x00	0x01	0x00	0x00	0x21

• Type: Write Command
• Guest Address: 0x00
• Register Address: 0x0020
• Command Description: after the previous command is executed, the guest will be defined as the single measurement in automatic mode, and the laser will be turned off after one measurement.
• Guest Feedback:

Byte	0	1	2	3	4	5	6:9	10:11	12
Name	First byte	Read & Write direction indicator bit / Current guest address	Register address		Number of valid data		Valid data	Signal quality	Checksum
Data	0xAA	0x00	0x00	0x22	0x00	0x03	0xAABBCCDD	0x0101	Checksum

• Guest return
• Guest address: 0x00 Register address: 0x0022
• Function: Return the measurement result to the host.
• Measurement Result=0xAABBCCDD millimeters (byte 6=0xAA, byte 7=0xBB, byte 8=0xCC, byte 9=0xDD).
• Signal Quality=0x0101, The smaller the signal quality value, the stronger the laser signal and the more reliable the measurement results.

Low-Speed Singe Measurement

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read & Write direction indicia- tor bit / Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x00	0x00	0x20	0x00	0x01	0x00	0x01	0x22

• Type: Write Command Guest Address: 0x00 Register Address: 0x0020
• Command Description: After the previous command is executed, the guest will be defined as the low-speed single measurement mode. The measurement result is more accurate with the low-speed mode.
• Guest Feedback: Consistent with the single automatic measurement feedback command.

High-Speed Singe Measurement

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read & Write direction indicia- tor bit / Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x00	0x00	0x20	0x00	0x01	0x00	0x02	0x23

• Type: Write Command Guest Address: 0x00 Register Address: 0x0020
• Command Description: After the previous command is executed, the guest will be defined as the high-speed single measurement mode. The measurement result is less accurate than the low-speed measurement mode.
• Guest Feedback: Consistent with the single automatic measurement feedback command.

on tenuous Automat Measurement

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read & Write direction indica- tor bit / Current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x00	0x00	0x20	0x00	0x01	0x00	0x04	0x25

• Type: Write Command
• Guest Address: 0x00
• Register Address: 0x0020
• Command Description: After the previous command is executed, the guest will be defined as the continuous measurement in automatic mode. After sending the command, the module will continuously measure the distance at a fixed frequency.
• Guest Feedback: Consistent with the single automatic measurement feedback command.

Low Speed on Tenuous Measurement

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read/write direction indicator bit/current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x00	0x00	0x20	0x00	0x01	0x00	0x05	0x26

• Type: Write Command
• Guest Address: 0x00
• Register Address: 0x0020
• Command Description: After the previous command is executed, the guest will be defined as the continuous measurement in low-speed mode.
• Guest Feedback: Consistent with the single automatic measurement feedback command.

High Speed on tenuous Measurement

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read/write direction indicator bit/current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x00	0x00	0x20	0x00	0x01	0x00	0x06	0x27

• Type: Write Command
• Guest Address: 0x00
• Register Address: 0x0020
• Command Description: After the previous command is executed, the guest will be defined as the continuous measurement in high-speed mode.
• Guest Feedback: Consistent with the single automatic measurement feedback command.

Error Feedback

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read/write direction indicator bit/current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xEE	0x00	0x00	0x00	0x00	0x01	0x00	0x0F	0x10

• Type: Guest feedback
• Guest Address: 0x00
• Register Address: 0x0000
• Command Description: Feedback error status code to the host. Error status code=0x000F. For specific error codes, please refer to 6.1 Status Code.

Extont tenuous Measurement Mode

The host transfers 1-byte 0x58 (Capital ‘X’ in ASCII) to stop the continuous measurement mode immediately.

Enable Mu t node Measurement

The host sends a measurement command to the guest address 0x7F, which will make all online guests to measure the distance simultaneously, the results will not be returned until the host requests the guests to return measurements. Before sending a command to read the measurement results, the host should read the guests’ status code to ensure no errors will occur when the guests are working.

Byte	0	1	2	3	4	5	6	7	8
Name	First byte	Read/write direction indicator bit/current guest address	Register address		Number of valid data		Valid data		Checksum
Data	0xAA	0x7F	0x00	0x20	0x00	0x01	0x00	0x00	0xA0

• Type: Write Command
• Guest Address: 0x00
• Register Address: 0x0020
• Command Description: After the previous command is executed, define all guests to be in single
• automatic measurement mode.
• Guest Feedback: NONE

After sending the command, the host polls the status of all guests; If the status code provided by the guest is 0x0000, indicating no errors, a command to read the measurement results can be sent to read the distance; All guests will not rewrite the previous measurement result until they have successfully received the measurement command and measured a new distance value.

Quick Testing Guidance

• Preparat on Before Test ng

Quick Testing Steps

• Procedures
• Select Serial Port Number
• Select Module Type Select Baud Rate
• Select Check Method
• Select Module Address
• Click on ‘Open Serial Port’
• Click and check the module information to be queried
• Click and check the measurement mode to be used
• Check test results
• Choose whether to export the data

If you need to quickly verify the basic functions of the module, you can follow the steps shown in Figure 16-1 for testing

Set offset

• Click on “Open Serial Port”
• Enter the desired offset value in the input box Click on “Set Offset” to finish setting

Reset baud rate

• Choose the desired baud rate in the drop-down box
• Click on “Reset Baud Rate” to finish reset

Set address

• Click on “Open Serial Port”
• Enter the current address in the “Old Address” input box Enter new address in the “New Address” input box Click on “Set Address” to finish setting

Check method

• Choose CRC or No
• Click on “Open Serial Port”

Custom command

• Click on “Open Serial Port” Tick “HEX” to send hex data
• Enter valid commands in the input box for custom commands Click on “Send Data”
• Input desired time intervals to send data periodically
• Tick ‘Periodic’， custom commands will be sent periodically as per time intervals

Show line chart

• Click on “Open Line Chart” to show line chart when the module is working
• The measurement values will be recorded and displayed on the line chart
• Click on “Start tracking”, and users are able to see the real-time line graph displaying the current
• distance values measured by the module
• Click on “Reset Graphics” to clear the line chart

Precautions for Use

• Please do not look directly at the laser beams
• Please strictly follow the recommended electrical parameters when using the
• Please ensure the power supply has been cut off before the wiring
• Please strictly follow instructions when wiring
• Please keep the front end of the optical lens clean to ensure normal use

After Sales and Maintenance

• The product has a one-year warranty from the date of original shipment
• Warranty does not apply to:

a.Failure or damage due to improper operation b.Failure or damage due to force majeure

c.For other matters, please contact Meskernel’s customer service

Contact Us

www.meskernel.com

Email: sales@meskernel.com Tel: 0086-28-83533012

Fax: 0086-28-83151207

Address: No. 288, Section 2, Airport 1st Road, Shuangliu District, Chengdu City, Sichuan Province, People’s Republic of China

UNITY FOCUS INTEGRITY PROGRESS
Committed to becoming a leader in the field of laser measurement!

Documents / Resources

Meskernel LDJ100-689 Laser Distance Sensor [pdf] User Manual LDJ100-689, LDJ100-689, LDJ100-689 Laser Distance Sensor, LDJ100-689, Laser Distance Sensor, Distance Sensor, Sensor

References

• User Manual