BW SENSING BW-IMU300 User manual

BW-IMU300 Serials
Low-cost Inertial Measurement Unit
Technical Manual

As a low-cost inertial measurement sensor, the BW-IMU300 measures the attitude
parameters of the motion carrier (roll angle, pitch angle, angular velocity, acceleration).Attitude
and angular velocity deviations are estimated by a 6-state Kalman filter with appropriate gain, that is suitable for
inertial attitude measurement in motion or vibration.
BW-IMU300 uses highly reliable MEMS accelerometers and gyroscopes，and ensure measurement
accuracy through algorithms, meanwhile, the seal design and strict process ensure that the dynamic parameters of the
carrier such as the angular velocity、acceleration and attitude can be accurately measured under harsh conditions. Through
various compensations such as nonlinear compensation, quadrature compensation, temperature compensation and drift
compensation, the error source of BW-IMU300 can be greatly eliminated, and the product accuracy level can be improved.
The BW-IMU300 is equipped with digital interface that can be easily integrated into the user's system.
Introduction
Features
Applications
●Dynamic compensation and quadrature
compensation
●Accuracy：0.5°
●Special offset tracking algorithm eliminates drift
●Gyro drift compensation
●Standard RS232/RS485/TTL output interface
●Operating temperature:： -40℃+85℃，temperature
compensation
●High-performance Kalman filter algorithm
●Small size： L60 × W59× H29mm
BW-IMU300
Low-cost inertial measurement unit
●Ship
●Construction machinery
●Platform stability
●Agricultural machinery
●Special vehicle
●Driverless
●Robot
●Aircraft
Bewis Sensing Technology LLC
www.bwsensing.com Tel: [phone]

Power supply
Operating current
Operating temperature
Store temperature
9-35V DC
30mA （Max 40mA ）
-40~85℃
-55~100℃
Specifications
Performance Specifications
Pitch angle
Roll angle
Accuracy
measuring range
Accuracy
Resolution
Range
Resolution 0.01°/sec
-180 °~180°
0.01°
0.5°
-90°~90°
0.5°
Resolution 0.01°
Gyro
Range
Zero instability
ARW
Noise density
Zero absolute error ±0.1 °/sec
0.003 °/s/√Hz
1 °/√h
40 °/h
±350°/sec
Range： X,Y,Z
Resolution 0.5 mg
±2 g
Accelerometer
Bias stability
100Hz
Maximum output frequency
±2 mg
50ms
Start delay
2000g
Anti-vibration performance
BW-IMU300
Low-cost inertial measurement unit
Electrical Specifications
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www.bwsensing.com Tel: [phone]

Bare plate product size
Product size：L44*W35*H11（mm） Note: ±1mm error for length and width dimensions,
please refer to actual size
hole Φ 2mm
30
39
44
35
Product Size：L60*W59*H29（mm)
Connector
Protection level
Shell material
Installation
Metal connector（standard cable is 1.5m）)
IP67
Magnesium alloy sanding oxidation
Four M4 screws
Mechanical Characteristic
Package size
BW-IMU300
Low-cost inertial measurement unit
Resolution: The measured minimum change value that the
sensor can detect and resolve within the measurement range.
Accuracy: The error between the actual angle and the Root mean
square(RMS) of the measured angle of the sensor (≥16 times).
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Bewis Sensing Technology LLC

The correct installation method can avoid measurement error. The following points should be made
when installing the sensor:
First of all, to ensure that the sensor mounting surface and the measured surface completely close,
the measured surface should be as horizontal as possible, can not have the angle shown in Figure A
and Figure C, the correct installation is shown in Figure B and Figure D.
the measured surface the measured surface
C D
the measured surface the measured surface
AB
Secondly, the bottom cable of the sensor and the axis of the measured object shouldn't generate
the angle shown in E. When installing, the bottom cable of the sensor should be kept parallel or
orthogonal to the rotation axis of the measured object. This product can be installed horizontally or
vertically (vertical installation requires customization). The correct installation method is shown in
Figure F.
Finally, the installation surface of the sensor must be fixed with the measured surface tightly and
smoothly, to avoid measurement error that may be caused by the acceleration and vibration.
Installation direction
BW-IMU300
Low-cost inertial measurement unit
uneven surface
generates the
angle
uneven surface
generates the
angle
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BW-IMU300
Low-cost inertial measurement unit
Electrical interfaces
Inertial
measureme
nt unit
1
3
4
5
GND
DC 9-35V
1
5
4
2
3
6
7
8
9
BLACK GND
YELLOW TXD
RED VCC
GREEN RXD
RS 232 wiring diagram
RED
1
VCC
DC 9-35V
BLUE
2
NC
BLACK
3
GND
GREEN
4
RXD
（B、D-）
YELLOW
5
TXD
（A、D+）
Sensor
YELLOW: TXD
DC 10-35V
6
8
9
3
2
4
5
1
3
73
2
4
5
6
8
9
RED VCC DC 9-35V
YELLOW A 485+
485-
BLACK GND
RS 485 wiring diagram
GND
11
Signal
acquisition
terminal
Inertial
measureme
nt unit
1
3
4
5
GREEN B
Electrical connections
Cable color
&
function
Note: The RS232 interface needs to share the product ground wire with the
communication ground wire.
Bewis Sensing Technology LLC www.bwsensing.com Tel: [phone]

BW-IMU300
Low-cost inertial measurement unit
Debugging software
Users can directly download serial assistant on official website (Supports-Download). You can also use more
convenient and intuitive PC software.
BW-IMU300 supporting serial debugging software can be connected to the inclinometer on the computer for
angle display. The software debugging interface is as shown in the figure below. Using the debug software, it
can conveniently display the current X-direction tilt angle, and you can also modify and set other parameters by
yourself.
Software usage steps
①
②
③
Connect the serial port hardware of the inclinometer correctly and connect the power supply.
Select the computer serial port and baud rate and click to connect to the serial port.
Click Start and the tilt angle of the inclinometer in the X and Y directions will be displayed on the screen.
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Protocol
1Data Frame Format：
Data Format: Hexadecimal
Identifier: Fixed to 77
Frame Length: Length from Frame Length to Checksum（included）
Address Code: Address of acquiring module, default 0x00
Data: Content and length variable according to Command
Checksum: Sum of Frame Length, Address Code, Command and Data. (Please pay
attention that when the command or data changes, the checksum will change. )
（8 data bits，1 stop bit，No parity check，default baud rate 9600）
Identifier
（1byte）
0x77H
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（Xbyte）
Checksum
（1byte）
2 Command Format：
2.1 Read PITCH angle Command：77 04 00 01 05
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（0byte）
Checksum
（1byte）
0x01
Command response：
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（3byte）
Checksum
（1byte）
0x81 SXXX.YY
Note: Data represents 3 byte angle value in format of compressed BCD code. S is the sign bit (0 means positive, 1
means negative), XXX is the three digit integer part, YY is the fractional part. For example, if the return value is 77 07
00 81 10 34 63 2F, the pitch angle data is “10 34 63”, which means “-34.63 degrees”.”
0x07
0x07
0x04 0x05
2.2 Read ROLL angle Command： 77 04 00 02 06
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（0byte）
Checksum
（1byte）
0x02
Command response：
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（3byte）
Checksum
（1byte）
0x82 SXXX.YY
0x04 0x06
Note: Data represents 3 byte angle value in format of compressed BCD code. S is the sign bit (0 means positive, 1
means negative), XXX is the three digit integer part, YY is the fractional part.For example, if the return value is 77 07 00
82 01 23 57 04, the roll angle data is "01 23 57", which means "123.57 degrees"
BW-IMU300
Low-cost inertial measurement unit
Bewis Sensing Technology LLC www.bwsensing.com Tel: [phone]

SXXX.YY
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（0byte）
Checksum
（1byte）
Command response：
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（9byte）
Checksum
（1byte）
0x84
2.3 Read PITCH, ROLL axis angle Command：77 04 00 04 08
0x040x04
0x0D
PITCH axis： +2.01°，ROLL axis： -0.51°，YAW axis：0.00°
77 0D 00 84 00 02 01 10 00 51 00 00 00 F5
Identifier;
fixed as 77
The length of the data,
fixed to 0D means that
in addition to 77, there
are 13 bytes behind
Address code,
default is 00
Command word,
fixed at 84
ROLL axis angle:
The format is the
same as the PITCH
axis
YAW axis or reserved
bit angle: the format
is the same as the
PITCH axis
The last byte is the sum
of all the previous data
except the first number
(0x77). If there is a carry,
the lower data is taken.
PITCH axis angle:
The first digit of the first byte is the
sign bit, 0 is the positive angle, and 1
is the negative angle.
The second and second bytes of the
first byte are integer bits of the angle,
which are compressed BCD codes.
The third byte is the decimal place of
the angle, which is the compressed
BCD code.
BW-IMU300
Low-cost inertial measurement unit
Bewis Sensing Technology LLC www.bwsensing.com Tel: [phone]

Command response：
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（1byte）
Checksum
（1byte）
Identifier
（1byte）
0x77
0x05 0x8B
0x05
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（1byte）
Checksum
（1byte）
0x0B XX
Command：77 05 00 0B 02 12
2.4 Set baud rate
Note: 0x00 means 2400 0x01 means 4800 0x02 means 9600 0x03 means 19200, 0x04 means 115200, default
value is 0x02:9600 Each time the communication baud rate is changed successfully, the response command is
sent back at the original baud rate, and then the device communication baud rate is changed immediately.
Note: If high frequency output is required, set the baud rate to 115200. Modify the baud rate without sending
a save command, and it will take effect immediately.
0x00: success
0xFF: failure
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（1byte）
Checksum
（1byte）
Command response：
2.5 Set module address
0x0F
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（1byte）
Checksum
（1byte）
0x8F
Command：77 05 00 0F 01 15
new address
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（0byte）
Checksum
（1byte）
Command response：
2.6 Query current address
0x1F
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（1byte）
Checksum
（1byte）
0x1F
Command： 77 04 00 1F 23
0x00: success
0xFF: failure
0x04
0x05
0x05
0x05
new address
0x00 0x23
new address new address
correct address
Note: For example, the following command "77 05 00 0F 0A 1E" means that the address of the product is changed
from hexadecimal address 00 to 0A.
Note: The query address command is to fix the command.。
BW-IMU300
Low-cost inertial measurement unit
Bewis Sensing Technology LLC
www.bwsensing.com Tel: [phone]

Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（1byte）
Checksum
（1byte）
Command response：
2.7 Set the output frequency
0x0C
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（1byte）
Checksum
（1byte）
0x8C
Command：77 05 00 0C 00 11
0x00: success
0xFF: failure
XX
The transmitted data field XX is the automatic output frequency option: 00 indicates the answer mode,
01 indicates 5Hz automatic output corresponding data type parameter
02 indicates 10Hz automatic output corresponding data type parameter
03 indicates 20Hz automatic output corresponding data type parameter
04 indicates 25Hz automatic output corresponding data type parameter
05 indicates 50Hz automatic output corresponding data type parameter
06 indicates 100HZ automatic output Corresponding data type parameter
Note: 1. When the automatic output frequency setting is high, the baud rate needs to be set to a high baud rate. Under
some data types, 100HZ cannot be output due to the baud rate limit.
2. The automatic output data type parameter is determined according to the following data type selection command. The
default is the automatic output angle.
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（0byte）
Checksum
（1byte）
Command response：
2.8 Query gravitational acceleration g
0x54
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（9byte）
Checksum
（1byte）
0x54
Command： 77 04 00 54 58
0x04
0x0D SXYYYY
0x05
0x05
Note: The data field part is the value of g value of pitch, roll, Z axis (vertical horizontal plane), which consists of 1 bit sign
bit + 1 bit integer bit + 4 decimal places.
If the return value is "77 0D 00 54 00 01 07 00 94 21 10 06 30 64", they are 0.0107g, 0.9421g, -0.0630g respectively.
BW-IMU300
Low-cost inertial measurement unit
Bewis Sensing Technology LLC www.bwsensing.com Tel: [phone]

Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（0byte）
Checksum
（1byte）
Command response：
2.10 Save settings
0x0A
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（1byte）
Checksum
（1byte）
0x8A
Command： 77 04 00 0A 0E
00:success
FF: failure
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（0byte）
Checksum
（1byte）
Command response：
2.11 Quaternion
0x57
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（16byte）
Checksum
（1byte）
0x57
Command： 77 04 00 57 5B
SXYYYYYY
0x04
0x14
0x04
0x04
Note: It is not necessary to save the settings to set the baud rate. Other settings need to send the save settings.
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（0byte）
Checksum
（1byte）
Command response：
2.9 Query angular velocity
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（9byte）
Checksum
（1byte）
Command： 77 04 00 50 54
SXXXYY
0x04
0x0D
0x50
0x50
Note: The data field is the pitch, roll, and Z-axis (vertical horizontal) angular velocity. It consists of 1 sign bit + 3 integer
bits + 2 decimal places.
For example, the return value is “77 0D 00 50 10 93 76 14 98 87 00 14 03 C0”. The data field parts are: pitch axis
angular velocity: -93.76°/s, roll axis angular velocity: -498.87°/s Z-axis angular velocity :+14.03°/s
BW-IMU300
Low-cost inertial measurement unit
Bewis Sensing Technology LLC www.bwsensing.com Tel: [phone]
Note: The data field contains 16 bytes, 4 bytes are a group, respectively
quaternary q0, q1, q2, q3, which is a compressed BCD code, the format is
SX YY YY YY, S is a sign bit (0 positive, 1 negative), X is a 1-bit integer bit,
and YYYYYY is a 6-digit decimal place. For example, the return command
77 14 00 57 00 99 99 96 00 00 02 90 10 00 26 73 10 00 00 01 7F
Then the quaternion data are:
Where q0 is 00 99 99 96, representing 0.999996.
q1 is 00 00 02 90, which means 0.000290
q2 is 10 00 26 73, which means -0.002673
q3 is 10 00 00 01, indicating -0.000001

Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（1byte）
Checksum
（1byte）
Command response：
2.13 Automatic output data type selection
0x56
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（1byte）
Checksum
（1byte）
0x56
Command： 77 05 00 56 00 5B
00
0x05
0x05
XX
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（0byte）
Checksum
（1byte）
Command response：
2.12 Simultaneous reading angle, accelerometer, gyroscope, quaternion
0x59
Identifier
（1byte）
0x77
Frame Length
（1byte）
Address Code
（1byte）
Command
（1byte）
Data
（43byte）
Checksum
（1byte）
0x59
Command： 77 04 00 59 5D
0x04
0x2F Data field
-
Note: The data field contains 43 bytes, which are angle, gravitational acceleration g value, angular velocity, quaternion,
compressed BCD code, four elements are the last 16 bytes, 4 bytes are a group, a total of 4 groups The rest is a group of
3 bytes, indicating the method to see the corresponding parameter return value.
For example, the return value is:
77 2F 00 59 10 00 60 10 03 06 00 00 00
10 01 07 10 05 43 01 01 54
10 00 13 10 00 04 00 00 09
10 87 06 35 00 01 76 91 00 02 06 94 00 49 11 75 5C
Then: the three axis angles are -0.6 degrees, -3.06 degrees, 0 degrees;
The g values of the three axes were -0.0107 g, -0.0543 g, and 1.0154 g, respectively;
The three angular angular velocities are -0.13 ° / s, -0.04 ° / s, 0.09 ° / s;
The four quaternions are -0.870635, 0.017691, 0.020694, 0.491175
BW-IMU300
Low-cost inertial measurement unit
Bewis Sensing Technology LLC
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Note: Data field XX is the corresponding output data type, which needs to be performed in automatic output
mode:
0x00: When outputting automatically, the output parameter is triaxial angle data, and the output format refers
to command 2.3;
0x01: When the output is automatic, the output parameter is the triaxial acceleration value, and the output
format refers to the command 2.8;
0x02: When outputting automatically, the output parameter is the value of the three-axis gyroscope, and the
output format refers to the command 2.9;
0x03: When outputting automatically, the output parameter is triaxial angle data (reserving other data types);
0x04: When outputting automatically, the output parameter is a quaternion value, and the output format refers
to the command 2.11.
0x05: When outputting automatically, the output parameters are composed of angle, acceleration, angular
velocity and four elements. The output format refers to command 2.12.

Ordering Information
Executive standard
●Enterprise Quality System Standard: ISO9001:2008 Standard
(Certificate No.:10114Q16846ROS)
●CE certification (certificate number: 3854210814)
●ROHS (certificate number: SO81426003)
●GB/T 191 SJ 20873-2003 General specifications for tiltmeters and
spirit levels
●GBT 18459-2001 sensor main static performance index calculation
method
●JF 1059-1999 Evaluation and Expression of Measurement Uncertainty
●GBT 14412-2005 mechanical vibration and shock mechanical
installation of accelerometer
●General requirements for GJB 450A-2004 equipment reliability
●Quality control of key parts and important parts of GJB 909A
●GJB 899 Reliability Qualification and Acceptance Test
●GJB 150-3A high temperature test
●GJB 150-4A low temperature test
●GJB 150-8A rain test
●GJB 150-12A dust test
●GJB 150-16A vibration test
●GJB 150-18A impact test
●GJB 150-23A Tilt and Swing Test
●GB/T 17626-3A RF electromagnetic radiation immunity test
●GB/T 17626-5A surge (hit) impulse immunity test
●GB/T 17626-8A power frequency magnetic field immunity test
●GB/T 17626-11A voltage dips, short interruptions and voltage
changes immunity
Product number Package condition
BW-IMU300-485
BW-IMU300-232
BW-IMU300-TTL
IP67 Package/Metal Connector
IP67 Package/Metal Connector
IP67 Package/Metal Connector
BW-IMU300
Low-cost inertial measurement unit
Way of communication
RS232
TTL
485
RS
Bewis Sensing Technology LLC
www.bwsensing.com Tel: [phone]

BW-IMU300 Serials
Low-cost inertial
measurement unit
Wuxi Bewis Sensing Technology LLC
Address: Building 30, No. 58 Xiuxi
Road, Binhu District, Wuxi City Hotline:
400-618-0510
Tel: [phone]-801
Email: [email protected]
Website: www.bwsensing.com