HRXL-MaxSonar
®
- WRS
™
Series
HRXL-MaxSonar - WRS Series
High Resolution, IP67 Weather Resistant, Ultrasonic
Snow Depth Sensor /
MB7334, MB7344, MB7354, MB7364, MB7374, MB7384
6
The HRXL-MaxSonar-WRS sensor line is a cost-effective solution for applications where precision
range-finding, low-voltage operation, space saving, low-cost, and IP67 weather resistance rating is needed. This sensor
component module allows users of other, more costly precision ultrasonic snow depth measurement rangefinders to
lower the cost of their systems without sacrificing performance. Additionally, this sensor line allows cost-sensitive
designers to choose this precision sensor as a performance upgrade over other lower performance sensors. The HRXL-
MaxSonar-WRS sensor line provides high accuracy and high resolution ultrasonic proximity detection and ranging in
air, with an IP67 weather resistant rating. This sensor line features 1-mm resolution, target-size and operating-voltage
compensation for improved accuracy, superior rejection of outside noise sources, internal speed-of-sound temperature
compensation and optional external speed-of-sound temperature compensation. The HRXL-MaxSonar-WRS sensors
have a maximum range of 5-meters.
This ultrasonic sensor detects objects from 1-mm and ranges to objects from 50-cm to maximum range. Objects closer
than 50-cm are typically reported as 50-cm. The interface output formats are pulse width, analog voltage, and digital
serial in either RS232 or TTL . Factory calibration is standard.
Very Low Power Requirements
•
Sensor automatically handles
Precision Ultrasonic Range
acoustic noise
1,2
Sensing
•
Wide, low supply voltage
•
Small and easy to mount
requirements eases battery powered
•
Range-finding at a fraction of the
•
Calibrated sensor eliminates most
design
cost of other precision rangefinders
sensor to sensor variations
•
Reading-to-reading stability of 1-mm
•
Low current draw reduces current
drain for battery operation
at 1-meter is typical
1
Applications & Uses
•
Fast first reading after power-up
•
Accuracy is factory-matched
•
Weather station monitoring
eases battery requirements
providing a typical accuracy of 1%
•
Snow level measurement (MB7354,
or better
1,2
•
Very low-power rangerfinder,
MB7374)
excellent for multiple sensor or
•
Compensation provided for target
•
Bin level measurement
battery based systems
size variation and operating voltage
•
Corn level measurement
range
Easy to use Component
•
People detection
•
Internal temperature compensation is
Module
•
This product is not recommended as
standard
•
Gracefully handles other ultrasonic
a device for personal safety
sensors
3
•
Optional external temperature
Notes:
1
•
Stable and reliable range readings
compensation
Users are encouraged to evaluate the sensor performance
in their application
and excellent noise rejection make
•
Determines range to first detectable
2
the sensor easy to use for most users
3
by design 7 for multi-sensor operation
object
See page
4
F-Option provides additional protection from hazardous
•
Easy to use interface with distance
•
Excellent clutter rejection
chemical environments
5
provided in a variety of output
Please reference page 12 for minimum operating voltage
•
Additional chemical resistance
verses temperature information
6
available
4
Please reference page 16 for part number key.
•
Target size compensation provides
greater consistency and accuracy
_______________________________________________________________________________________________________________________________________
®
™
Close Range Operation
Applications requiring 100% reading-to-reading reliability should not use MaxSonar sensors at a distance closer than
50cm. Although most users find MaxSonar sensors to work reliably from 0 to 50cm for detecting objects in many
applications, MaxBotix
®
Inc. does not guarantee operational reliability for objects closer than the minimum reported
distance. Because of ultrasonic physics, these sensors are unable to achieve 100% reliability at close distances.
_______________________________________________________________________________________________________________________________________
Warning: Personal Safety Applications
We do not recommend or endorse this product be used as a component in any personal safety applications. This product is
not designed, intended or authorized for such use. These sensors and controls do not include the self-checking redundant
circuitry needed for such use. Such unauthorized use may create a failure of the MaxBotix
®
Inc. product which may result
in personal injury or death. MaxBotix
®
Inc. will not be held liable for unauthorized use of this component.
MaxBotix
®
Inc.
Copyright 2005 - 2012 MaxBotix Incorporated
Patent 7,679,996
MaxBotix Inc., products are engineered and assembled in the USA.
Page 1
Web:
www.maxbotix.com
PD12593e
HRXL-MaxSonar
®
- WRS
™
Series
General Characteristics
•
•
•
•
Low cost ultrasonic rangefinder
Detection out to 5-meters
Resolution of 1-mm
Distance sensor from 50-cm to
5-meters
•
Excellent
1
Mean Time Between
Failure (MTBF)
•
Triggered operation yields real-time
range data
•
Free run operation with superior
noise rejection
3
•
Operating temperature range
from -40°C to +65°C
•
Operating voltage from 2.7V to 5.5V
•
Best operated at 5V for snow
applications
•
Nominal current draw of 2.3mA at
3.3V, and 3.1mA at 5V
•
IP67 Rated
Range Outputs
•
•
•
•
Pulse width, 1uS/mm resolution
Analog Voltage, 5-mm resolution
Serial, 1-mm resolution
Available in RS232 or TTL
About Ultrasonic Sensors
Our ultrasonic sensors are, non-contact object detection and ranging sensors that detect objects in air, within an area.
These sensors are not affected by color or other visual characteristics of the detected object. Ultrasonic sensors use high
frequency sound to detect and localize objects in a variety of environments. Ultrasonic sensors measure the time of flight
for sound that has been transmitted to and reflected back from nearby objects. Based upon the time of flight, the sensor
then outputs a range reading.
HRXL-MaxSonar-WRS
The HRXL-MaxSonar-WRS is a low-cost, rugged ultraso-nic snow depth sensor that is optimized for reliable snow depth
measurement. Internally, multiple sensor readings are analyzed using algorithms optimized for snow measurement,
ensuring accurate snow depth measurements. The sensor accurately applies temperature compensation to every reading,
using either the integrated temperature sensor or the optional external temperature sensor (HR-MaxTemp).
_______________________________________________________________________________________________________________________________________
HRXL-MaxSonar
®
-WRS
™
Mechanical Dimensions
______________________________________________________________________________________________________________________________________
MaxBotix
®
Inc.
Copyright 2005 - 2012 MaxBotix Incorporated
Patent 7,679,996
MaxBotix Inc., products are engineered and assembled in the USA.
Page 2
Web:
www.maxbotix.com
PD12593e
HRXL-MaxSonar
®
- WRS
™
Series
HRXL-MaxSonar-WR Pin Out
Pin 1- Temperature Sensor Connection:
Leave this pin unconnected if an external temperature sensor is not used. For
best accuracy, this pin is optionally connected to the HR-MaxTemp temperature sensor. Some additional information for
the temperature sensor can be found on page # of the datasheet.
Pin 2- Pulse Width Output:
This pin outputs a pulse width representation of the distance with a scale factor of 1uS per
mm. The pulse width output is sent with a value within 0.5% of the serial output.
Pin 3- Analog Voltage Output:
This pin outputs a single ended analog voltage scaled representation of the distance.
This output is referenced to the sensor ground and Vcc. After the ~50mS power up initialization, the voltage on this pin
is set to a low voltage. Once the sensor has completed a range reading the voltage on this pin is set to the voltage
corresponding to the latest measured distance.
The HRXL-MaxSonar-WRS sensors use a scale factor of (Vcc/5120) per 1-mm. The distance is output with a 5-mm
resolution. The analog voltage output is typically within ±5-mm of the serial output.
Using a 10-bit analog to digital converter with the HRXL-MaxSonar-WRS sensors, one can read the analog voltage
counts (i.e. 0 to 1023) directly and just multiply the number of counts in the value by 5 to yield the range in mm. For
example, a converted value of 60 corresponds to 300-mm (where 60 x 5 = 300), and 1000 counts corresponds to 5,000-
mm (where 1000 x 5 = 5,000-mm).
Pin 4- Ranging Start/Stop:
This pin is internally pulled high. If this pin is left unconnected or held high, the sensor will
continually measure and output the range data. If held low, the HRXL-MaxSonar-WRS will stop ranging. Bring high for
20uS or longer to command a range reading.
Filtered Range Data:
When pin 4 is left high on the sensors, the sensors will continue to range. The data that is output
includes a filter for increased accuracy. The sensors will output the range based on recent range information. The filter
does not affect the speed at which data is made available to the user but instead allows for more consistent range
information to be presented. For sensor specific timing and filter information refer to pages # and #.
Real-time Range Data:
When pin 4 is low and then brought high, the sensor will operate in real time and the first reading
output will be the range measured from this first commanded range reading. When the sensor tracks that the RX pin is low
after each range reading, and then the RX pin is brought high, unfiltered real time range information can be obtained. For
timing information please refer to pages # and #.
Pin 5-Serial Output:
The MB7334, MB7354, and MB7364 sensors have an RS232 data format (with 0V to Vcc levels)
and the MB7344, MB7374, and MB7384 sensors have a TTL outputs. The output is an ASCII capital “R”, followed by
four ASCII character digits representing the range in millimeters, followed by a carriage return (ASCII 13). The
maximum range reported is 4999 mm. A range value of 5000 corresponds to no target being detected in the field of view.
The serial data format is 9600 baud, 8 data bits, no parity, with one stop bit (9600-8-N-1).
Because the data is presented in a binary data format, the serial output is most accurate .
V+ Pin 6 -
Positive Power, Vcc: The sensor operates on voltages from 2.7V - 5.5V DC. For best operation, the sensor
requires that the DC power be free from electrical noise. For installations monitoring snow, powering the sensor at 5V
will provide the best results. (For installations with known dirty electrical power, a 100uF capacitor placed at the sensor
pins between V+ and GND will typically correct the electrical noise.) Please reference page 12 for minimum operating
voltage verses temperature information.
GND Pin 7 –
Sensor ground pin: DC return, and circuit common ground.
_______________________________________________________________________________________________________________________________________
MaxBotix
®
Inc.
Copyright 2005 - 2012 MaxBotix Incorporated
Patent 7,679,996
MaxBotix Inc., products are engineered and assembled in the USA.
Page 3
Web:
www.maxbotix.com
PD12593e
HRXL-MaxSonar
®
- WRS
™
Series
Sensor Mounting
It is recommended that several factors be taken into account when using the HRXL-MaxSonar-WRS ultrasonic snow
depth sensors.
Due to the high gain of the sensor, the first recommendation is to mount the sensor far enough away from any supporting
masts or towers. For a mast that is 5 meters high (or higher) the sensor should be mounted at least 100cm away from the
mast. For a mast that is 2.5 meters high (or lower) the sensor should be at least 75cm away from the mast. (This
corresponds to a mounting clearance angle of
≥11.3
degrees)
For users desiring the highest accuracy, it is recommended to use a properly mounted external temperature sensor.
MaxBotix Inc., is developing several components to assist in high accuracy readings and protection of the
HRXL-MaxSonar-WRS and HR-MaxTemp sensors.
The first component is a shroud that is assembled over the top of the HRXL-MaxSonar-WRS sensor housing, Figure 1.
This shroud is a UV shield for the sensor. The shroud is also acts to protect the sensor from hail, heavy snow, and snow
build up.
The second component is a louver design housing to protect the temperature sensor from direct and reflective UV rays,
Figure 2. This housing has been created to maintain a real time accurate temperature. This component is separate from
the shroud that covers the HRXL-MaxSonar-WRS.
The third component is a fan housing which is able hold either an AC or DC cooling fan under the temperature housing,
Figure 3. This has been created for maximum airflow to the temperature sensor housing. The fan housing helps to ensure
the temperature sensor is the same temperature as the surrounding environment.
All the components listed above are designed with the intent to use standard hardware for mounting to new or existing
weather stations or other mounting components.
Figure 4 shows the recommended mounting for the HRXL-MaxSonar-WRS snow depth sensor with the HR-MaxTemp
temperature sensor.
Mounting information for the snow sensor can be found in the application note here: ww.maxbotix.com/articles/070.htm
Figure 1
Figure 2
Figure 3
Figure 4
MaxBotix
®
Inc.
Copyright 2005 - 2012 MaxBotix Incorporated
Patent 7,679,996
MaxBotix Inc., products are engineered and assembled in the USA.
Page 4
Web:
www.maxbotix.com
PD12593e
HRXL-MaxSonar
®
- WRS
™
Series
Model Selection
Different applications require different sensors.
MaxBotix Inc., has made a variety of snow and high
sensitivity sensors available in order to best fit the
broad range of potential applications. Users are
encouraged to consider our other
HRXL-MaxSonar-WR products for applications
beyond snow.
For this product series the MB7364 and
MB7384 constitute the base model. The
MB7364 and MB7384 differ only in the
serial output provided. The MB7364 has
0-Vcc RS232 serial data (inverted data
that can be fed directly into a computer
equipped with a DB9 port), and the
MB7384 has TTL serial data.
Serial
Part Number Interface
MB7334
MB7344
MB7354
MB7364
MB7374
MB7384
RS232
TTL
RS232
RS232
TTL
TTL
Filter
High
Reset Performance
Window
HR Filter
1
2%
Yes
2%
Never
N/A
Never
N/A
Yes
Yes
Yes
Yes
Yes
Recom-
mended
Application
Water/Outdoors
Outdoors/Snow
Any
Outdoors/Snow
Any
5 Meter
Range
Yes
Yes
Yes
Yes
Yes
Yes
The MB7354 and MB7374 have an
additional filter on the data output for use
in outdoor applications with stationary or
Top (red): MB7364 reporting a target moved from 1 meter to 1.1 meters in a linear fashion.
slow moving targets. This filter has been
Middle (green): MB7334 responding to the same target, notice the steps when the target
shown to improve sensor accuracy and
moves > 2%.
usability in snow depth monitoring
Bottom (blue): MB7354 responding to a target moved from 1 meter to 1.1 meters in a linear
applications and will allow the user to get
consistent data even if the user only uses
fashion.
one reading to measure distance. In
order for this filter to run the sensor must be operated in free-run mode.
The MB7334 and MB7344 have an additional filter similar to the MB7354 and MB7374 except that the filter will reset to
targets that are considered valid outside of a 2% distance to target window. This makes the sensor an ideal balance for
accurately monitoring slow or stationary targets that occasionally move rapidly.
_______________________________________________________________________________________________________________________________________
Auto Calibration
Each time a HRXL-MaxSonar-WRS series sensor takes a range reading, it calibrates itself. The sensor then uses this data
to range objects. If the temperature, humidity, or applied voltage changes during sensor operation, the sensor will continue
to function normally over the rated temperature range while applying compensation for changes caused by temperature
and voltage.
Target Size Compensation
Most low cost ultrasonic rangefinders will report the range to smaller size targets as farther than the actual distance. In
addition, they may also report the range to larger size targets as closer than the actual distance.
The HRXL-MaxSonar-WRS sensor line compensates for target size differences. This means that, provided an object is
large enough to be detected, the sensor will report the same distance, typically within 1%, regardless of target size.
Smaller targets can have additional detection noise that may limit this feature. In addition, targets with small or rounded
surfaces may have an apparent distance that is slightly farther, where the distance reported may be a composite of the
sensed object(s). Compensation for target size is applied to all range outputs: pulse width, analog voltage, and serial
format output by the sensor.
Sensor operation from 30-cm to 50-cm
Because of acoustic effects in the near field, objects between 30-cm and 50-cm may experience acoustic phase
cancellation of the returning wave, resulting in inaccuracies of up to 5-mm. These effects become less prevalent as the
target distance increases, and have not been observed past 50-cm. For this reason, users that require the highest accuracy
are encouraged to mount the HRXL-MaxSonar-WRS farther than 50-cm away from objects.
MaxBotix
®
Inc.
Copyright 2005 - 2012 MaxBotix Incorporated
Patent 7,679,996
MaxBotix Inc., products are engineered and assembled in the USA.
Page 5
Web:
www.maxbotix.com
PD12593e
京公网安备 11010802033920号
EEWORLD
