MB7344-820_技术文档

HRXL-MaxSonar^®- WRS^™Series

High Resolution, IP67 Weather Resistant, Ultrasonic

Snow Depth Sensor / MB7334, MB7344, MB7354, MB7364, MB7374, MB7384⁶

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.

• Sensor automatically handles

acoustic noise ^1,2

• Small and easy to mount

• Calibrated sensor eliminates most

sensor to sensor variations

Very Low Power Requirements

Precision Ultrasonic Range

Sensing

• Range-finding at a fraction of the

cost of other precision rangefinders

• Reading-to-reading stability of 1-mm

at 1-meter is typical¹

• Accuracy is factory-matched

providing a typical accuracy of 1%

or better ^1,2

• Compensation provided for target

size variation and operating voltage

range

• Internal temperature compensation is

standard

• Optional external temperature

compensation

• Determines range to first detectable

object

• Wide, low supply voltage

requirements eases battery powered

design

• Low current draw reduces current

drain for battery operation

• Fast first reading after power-up

eases battery requirements

• Very low-power rangerfinder,

excellent for multiple sensor or

battery based systems

Applications & Uses

• Weather station monitoring

• Snow level measurement (MB7354,

MB7374)

• Bin level measurement

• Corn level measurement

• People detection

Easy to use Component

Module

• This product is not recommended as

a device for personal safety

Notes:

• Gracefully handles other ultrasonic

sensors³

¹Users are encouraged to evaluate the sensor performance

in their application

• Stable and reliable range readings

and excellent noise rejection make

the sensor easy to use for most users

• Easy to use interface with distance

provided in a variety of output

• Target size compensation provides

greater consistency and accuracy

²by design

³See page 9 for multi-sensor operation

⁴F-Option and P-Option provide additional protection

from hazardous chemical environments

⁵Please reference page 12 for minimum operating voltage

verses temperature information

• Excellent clutter rejection

•

Additional chemical resistance

available⁴

⁶Please reference page 17 for part number key.

_______________________________________________________________________________________________________________________________________

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.

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PD12593i

MaxBotix^®Inc.

MaxBotix Inc., products are engineered and assembled in the USA.

Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

• Operating temperature range from -40°C • Serial, 1-mm resolution

General Characteristics

to +65°C

• Available in RS232 or TTL

• Low cost ultrasonic rangefinder

• Detection out to 5-meters

• Resolution of 1-mm

• Operating voltage from 2.7V to 5.5V

• Best operated at 5V for snow

applications

• Distance sensor from 50-cm to 5-meters

• Excellent¹Mean Time Between Failure

(MTBF)

• Nominal current draw of 2.3mA at 3.3V,

and 3.1mA at 5V

• IP67 Rated

• Triggered operation yields real-time

Range Outputs

• Pulse width, 1uS/mm resolution

• Analog Voltage, 5-mm resolution

range data

• Free run operation with superior noise

rejection³

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 ultrasonic 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

3/4” NPS WR Housing

Extended Horn

B

I

J

F

E

C

D

Pin 1

A

3.12” dia.

7.20”

6.09”

0.58”

0.31”

79.3 mm dia.

182.9 mm

154.8 mm

14.4 mm

7.9 mm

B

C

D

E

F

G

H

I

A

G

0.23”

0.10”

5.8 mm

2.54 mm

3/4” - 14 National Pipe Thread Straight

1.03” dia.

H

26.2 mm dia.

34.8 mm

J

1.37”

Weight, 1.10 oz., 31.1 grams

Values Are Nominal

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MaxBotix Inc., products are engineered and assembled in the USA.

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PD12593i

Patent 7,679,996

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 8 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 10 and 11.

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 10 and 11.

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.

_______________________________________________________________________________________________________________________________________

Package Types Currently Available

Full Horn – 3/4” NPT straight; back mounted thread

Snow Horn – 3/4” NPT straight; back mounted thread. Enhanced detection of snow.

All package types have exposed PCB on user end for easy connection. Users desiring a fully enclosed assembly may purchase the

“Shielded Cable Option” along with their sensor.

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MaxBotix^®Inc.

MaxBotix Inc., products are engineered and assembled in the USA.

Patent 7,679,996

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 to 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

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MaxBotix^®Inc.

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Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

Filter

High

Recom-

mended

Application

Model Selection

Serial

5 Meter

Range

Reset Performance

Window

Part Number Interface

HR Filter¹

Yes

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.

MB7334

MB7344

MB7354

MB7364

MB7374

MB7384

RS232

TTL

2%

Yes

Water/Outdoors

2%

Yes

RS232

TTL

Never

N/A

Yes

Outdoors/Snow

Any

Yes

Never

N/A

Yes

Outdoors/Snow

Any

TTL

Yes

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.

The MB7354 and MB7374 have an

additional filter on the data output for use

in outdoor applications with stationary or

slow moving targets. This filter has been

shown to improve sensor accuracy and

usability in snow depth monitoring

applications and will allow the user to get

consistent data even if the user only uses

one reading to measure distance. In

order for this filter to run the sensor must

be operated in free-run mode.

Top(red):MB7364reportingatargetmovedfrom1meterto1.1metersinalinearfashion.

Middle(green):MB7334respondingtothesametarget,noticethestepswhenthetarget

moves>2%.

Bottom(blue):MB7354respondingtoatargetmovedfrom1meterto1.1metersinalinear

fashion.

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.

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MaxBotix^®Inc.

MaxBotix Inc., products are engineered and assembled in the USA.

Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

MB7334, MB7344 Filter – 2% distance to target filter

The MB7334 and MB7344 have a 2% distance to target

filter designed to provide more accurate information in

real-world environments. This filter improves sensor

accuracy and stability by reducing the influence of wind,

acoustic noise, thermal pockets, and other effects on the

sensor output. (This is in addition to the HR filtering

already available on the MB7364 and MB7384)

This filter can be reset at any time by bringing pin 4 (RX)

of the sensor low.

This filter is active whenever the RX pin is brought high,

all readings within a 2% distance to target window, are

collected and added to the output sent to the user using a

recent biased exponential weighted average.

The MB7334 range output when responding to a 4cm change.

Confirmed readings outside of the 2% distance to target window will cause the filter to reset. This allows the sensor to

continue functioning in a reasonable manner where high accuracy measurements are required for most of the sensor

operation and quick sensor response is required at other points of operation.

____________________________________________________________________________________________________________________________________

MB7354, MB7374 Filter

The MB7354 and MB7374 have a filter that improves sensor accuracy and stability by reducing the influence of wind,

acoustic noise, thermal pockets and other effects on the sensor output. (This is in addition to the HR filtering already

available on the MB7364 and MB7384.)

This filter can be reset at any time by bringing pin 4 (RX) of the sensor low.

This filter will initialize 40 readings (about 7 seconds) after sensor power is applied, or after the RX pin is brought high

and held high.

This filter is a recent biased exponential weighted average filter that is also rate limited to change a maximum of seven

mm per second taken and is designed to monitor stable, or slow moving objects, if a filter update is required this can be

accomplished with the RX pin.

MB7354 responding to a 1 meter change. This shows the

MB7354 responding to a 4 cenꢀmeter change. This shows the

7-mm rate limit along with the exponenꢀal ꢁlter.

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MaxBotix^®Inc.

MaxBotix Inc., products are engineered and assembled in the USA.

Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

Sensor Performance Information

Accuracy Information

Best accuracy during snow measurements is achieved when the air temperature is accurately measured midway between

the sensor and the ground. To this end MaxBotix Inc., has tested our snow sensor solution using the internal temperature

sensor, external temperature sensor and the external temperature sensor mounted in special Louvre housing with a fan.

Three million readings in each test configuration were then recorded over five days at our outside our facility with typical

temperature swings of 15C per day and the MB7354 ranging to a stable target. All of the readings fell within the 1%

tolerance in our test setup. The external temperature sensor, mounted with the special shield and fan, provided better

performance.

MB7354 with external temperature

sensor and no circulation fan

MB7354 without external temperature

sensor

MB7354 with external temperature

sensor and circulation fan

Below is a histogram, by quantity, of each reading observed.

MB7354 with External Temperature Sensor and Fan

MB7354 with External Temperature Sensor

MB7354 without External Temperature Sensor

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MaxBotix^®Inc.

MaxBotix Inc., products are engineered and assembled in the USA.

Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

Supply Voltage Compensation

During power up, the HRXL-MaxSonar-WRS sensors will calibrate itself for changes in supply voltage. Additionally, the sensor will

compensate if the supplied voltage gradually changes.

If the average voltage applied to the sensor changes faster than 0.5V per second, it is best to remove and reapply power to the sensor.

For best operation, the sensor requires noise free power . If the sensor is used with noise on the supplied power or ground, the

readings may be affected. Typically adding a 100uF capacitor at the sensor between the V+ and GND pins will correct most power

related electrical noise issues.

Sensor minimum distance

The HRXL-MaxSonar-WRS sensors have a minimum reported distance of 50-cm (19.7 inches). However, the

HRXL-MaxSonar-WRS will report targets up to the sensor face. For the HRXL-MaxSonar-WRS sensors, targets closer than 500-

mm will typically range as 500-mm.

Range “0” location

The HRXL-MaxSonar-WR reports the range to distant targets from where the threading and nut meet on the sensor housing as

shown in the diagram below.

In general, the HRXL-MaxSonar-WR will report the range to the leading edge of the closest detectable object. Target detection has

been characterized in the sensor beam patterns.

_____________________________________________________________________________________________________________________________________

HRXL-MaxSonar®-WR™ Temperature Compensation

On Board – Internal Temperature Compensation

The speed of sound in air increases by about 0.6 meters per second, per degree centigrade. Because of this, each HRXL-MaxSonar-

WR is equipped with an internal temperature sensor which allows the sensor to apply compensation for speed of sound changes.

The actual air temperature of the path between the sensor and the target may not match the temperature measured at the sensor itself.

Sensors can be mounted in vertical applications, or applications where the environment temperature gradient is severe. These users

may experience a temperature measurement error which will affect the sensor accuracy. For example, buildings with a height of 3-

meters can have floor to ceiling temperature variations of 5°C or more.

Because of these temperature effects, users desiring the highest accuracy output are encouraged to use a properly mounted external

temperature sensor or to manually account for this measurement error.

HR-MaxTemp, an External Temperature Sensor

Although the HRXL-MaxSonar-WR has an internal temperature sensor; for best accuracy, users are encouraged to use the optional

external temperature sensor. On power-up, the HRXL-MaxSonar-WR will automatically detect an attached HR-MaxTemp

temperature sensor and begin to apply temperature compensation using the external temperature sensor.

The external temperature sensor allows for the most accurate temperature compensation, by allowing temperature readings to be

taken that better reflect the composite temperature of the acoustic ranging path. For best results, users are encouraged to connect the

temperature sensor midway between the HRXL-MaxSonar-WR and the expected target.

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MaxBotix^®Inc.

MaxBotix Inc., products are engineered and assembled in the USA.

Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

HRXL-MaxSonar-WR Sensor Operating Modes

Free-Run Operation

When operating in free run mode, the HRXL-MaxSonar-WRS sensors are designed to be used in a variety of outdoor,

industrial, or indoor situations. Many acoustic noise sources will have little to no effect on the reported range of the

HRXL-MaxSonar-WRS sensors. Most range readings are accurately reported. If the range readings are affected, the

effect is typically less than 5-mm. This allows users to employ real-time ultrasonic distance sensing without the need for

additional supporting circuitry or complicated user software.

Multiple HRXL-MaxSonar-WRS sensors can be operated in the same general locations. The internal noise filter is able

to filter out the ultrasonic noise from other HRXL-MaxSonar-WRS sensors with minimal interference. Typically, when

operating with multiple sensors, the range readings will be within ±1 cm of the actual range to the intended target.

Independent Sensor Operation

The HRXL-MaxSonar-WRS sensors have the capability to operate independently when the user desires. When using the

HRXL-MaxSonar-WRS sensors in single or independent sensor operation, it is easiest to allow the sensor to free-run.

Free-run is the default mode of operation for all of the MaxBotix Inc., sensors. The HRXL-MaxSonar-WRS sensors have

three separate outputs that update the range data simultaneously: Analog Voltage, Pulse Width, and Serial Data. Below

are diagrams on how to connect the sensor for each of the three outputs for single or independent sensor operation.

Using Multiple Sensors in a Single System

Multiple HRXL-MaxSonar-WRS sensors can be used simultaneously in the same environment with little to no

interference (cross-talk). Even so, some cross-talk may still occur for users wishing to use a large number of sensors in

the same environment.

If interference is occurring in the sensor setup please visit www.maxbotix.com/chaining for diagrams on correcting

cross-talk between sensors.

Please take note that when the HRXL-MaxSonar-WRS sensors are operating in a chaining sequence the internal free-run

filter of the sensor is disabled, and the sensor will range in real-time.

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Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

Sensor Timing Diagrams

Power Up Timing

All parts have the same powerup timing.

Sensor Free-Run Timing

When operating in free run mode, the HRXL-MaxSonar-WRS sensors are designed to be used in a variety of outdoor,

Power up timing has

already occurred

Maximum

Refresh

Rate

Free

Run

Filter

Pulse

Width

Reported Reported

Serial

Data

Pin 4

Brought

Low

End of

Range

Cycle

Product

MB7334, MB7344, MB7354, MB7364, MB7374, MB7384

6.67Hz

1.33Hz

~135mS ~140mS

~147mS

~148mS

industrial, or indoor environments. Many acoustic noise sources will have little to no effect on the reported range of the

HRXL-MaxSonar-WRS sensors. Most range readings are accurately reported. If the range readings are affected, the effect

is typically less than 5-mm. This allows users to employ real-time ultrasonic distance sensing without the need for

additional supporting circuitry or complicated user software.

The HRXL-MaxSonar-WRS use an internal filter to process range data. This filter improves the sensor’s performance for

accuracy, noise rejection, and reading to reading stability. The filtering in the free-run operation also permits additional

acoustic and electrical noise tolerance.

On the HRXL-MaxSonar-WRS sensors, when pin 4 is left high, the sensor will continue to range, the data output includes

a filter for increased accuracy in environments with acoustic noise. The HRXL-MaxSonar-WRS 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.

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Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

Sensor Timing Diagrams Cont.

Triggered—Real-time Operation Timing

Power up timing has

already occurred

Pulse

Width

sent

(A)

Serial

Data sent

RX Pin

set low

End of

range

cycle

(D)

Maximum

Refresh

Rate

Product

(B)

(C)

MB7334, MB7344, MB7354, MB7364,

MB7374, MB7384

6.67Hz

~135mS

~140mS

~147mS

~148mS

Real-time or triggered operation allows users to take advantage of a few functions unavailable during free run mode.

When operating in triggered mode, an unfiltered maximum refresh rate can be achieved. This triggered operation allows

users to range targets moving away from or closer to the sensor faster than 240mm per reading.

Users can enter and remain in the real-time or triggered operation by making sure that before the end each range cycle, the

voltage level on Pin 4 is set low. After the sensor has completed the last reading, then Pin 4 is brought high. When Pin 4 is

brought high, a brand new range cycle starts and the HRXL-MaxSonar-WR will output the most recent range data without

filtering.

Readings during triggered operation are less accurate than the filtered operation by approximately ±5-mm. Because the

range readings are not filtered, noise tolerance can be greatly reduced. Care should be taken to make sure that only one

sensor is sampling range at a time.

Pulse Width data sent (Colum A) - Column A shows the approximate time that the sensor starts to output the pulse

width data. The Pulse Width output time can be as short as 300uS (minimum reported distance). For 5 meter sensors, the

pulse width can take as long as 5000uS (maximum reported distance) to be sent. For 10 meter sensors the Pulse Width

can take as long as 9999uS (maximum reported distance) to be sent.

Serial data sent (Colum B) - Column B shows the approximate time during each range cycle when the serial data is

output for the sensor. Range data takes ~8mS to be reported from the serial data output.

RX Pin set low (Column C) - When operating the HRXL-MaxSonar-WR in Triggered Operation, Pin 4 is must be

brought high for a time frame greater than 20uS (0.02mS) and less than the time in Column C in the chart above. If Pin 4

remains high for a period of time greater than the value in Column C, the sensor will switch into free-run filter operation.

End of Range Cycle (Colum D) - Column D shows the approximate time each range cycle takes to complete for each

sensor.

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MaxBotix Inc., products are engineered and assembled in the USA.

Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

Voltage vs Temperature

The graph below shows minimum operating voltage of the sensor verses temperature.

_______________________________________________________________________________________________________________________________________

HRXL-MaxSonar^®-WR^™Beam Patterns

Attenuation of Ultrasound

Attenuation, specifically absorption of sound through the air, restricts the maximum range of ultrasonic rangefinders. As

sound waves travel through the air, that air absorbs some of their energy. High frequency sounds like ultrasound are often

attenuated more quickly than lower frequency sounds. In addition to frequency, relative humidity also affect attenuation.

Warm air masses with low relative humidity will typically attenuate sound waves faster. As such performance of

ultrasonic devices may be limited at low relative humidity, especially when trying to detect targets at longer ranges.

Background Information Regarding our Beam Patterns

Each HRXL-MaxSonar-WR sensor has a calibrated beam pattern. Each sensor is matched to provide the approximate

detection pattern shown in this datasheet. This allows end users to select the part number that matches their given sensing

application. Each part number has a consistent field of detection so additional units of the same part number will have

similar beam patterns. The beam plots are provided to help identify an estimated detection zone for an application based

on the acoustic properties of a target versus the plotted beam patterns.

People Sensing:

Each beam pattern is a 2D representation of the detection area of the sensor. The beam pattern is

For users that

actually shaped like a 3D cone (having the same pattern both vertically and horizontally). Beam

desire to detect

patterns for dowels are used to show the beam pattern of each sensor. Dowels are long cylindrical

people, the

targets of a given diameter. The dowels provide consistent target detection characteristics for a

given size target which allows easy comparison of one MaxSonar sensor to another MaxSonar

sensor.

detection area to

the 1-inch

diameter dowel, in

general, represents

the area that the

sensor will

For each part number, the four patterns (A, B, C, and D) represent the detection zone for a given

target size. Each beam pattern shown is determined by the sensor’s part number and target size.

reliably detect

people.

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Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

The actual beam angle changes over the full range. Use the beam pattern for a specific target at any given distance to

calculate the beam angle for that target at the specific distance. Generally, smaller targets are detected over a narrower

beam angle and a shorter distance. Larger targets are detected over a wider beam angle and a longer distance.

Beam Pattern Target Shapes

A 6.1-mm (0.25-inch) diameter dowel 4ft length

B 2.54-cm (1-inch) diameter dowel 4ft length

C 8.89-cm (3.5-inch) diameter dowel 4ft length

D 11-inch wide board 4ft in length moved left to right with the

board parallel to the front sensor face. This shows the

sensor’s range capability.

Corner Reflectors

Sometimes when using an ultrasonic sensor, users experience detection of unwanted objects that appear outside the

expected beam pattern. These types of detections are the result of reflectors present in the environment. Corner reflectors

can be surprisingly small, yet present a large reflection back to the sensor. Certain objects are prone to causing corner

reflections. One of the most common corner reflectors is two flat surfaces joining together to create a 90° angle. A half-

circle also acts as a similar reflector. You can learn more about corner reflectors in our Cube Corner Reflectors article.

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Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

MB7334-MB7344 HRXL-MaxSonar^®-WRS^™Beam Pattern and Uses

The HRXL-MaxSonar-WRS is a low-cost, rugged ultrasonic snow depth sensor that is optimized for reliable snow depth

measurement. Sensor readings are optimized for snow measurement, ensuring accurate snow depth measurement

Applications and Uses

Features and Benefits

• Snow depth measurement

• Weather station monitoring

• Soft target detection

• Water

• Factory calibrated beam width

• All range outputs are active

simultaneously

• High acoustic sensitivity

• Outdoors applications

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MaxBotix Inc., products are engineered and assembled in the USA.

Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

MB7354-MB7374 HRXL-MaxSonar^®-WRS^™Beam Pattern and Uses

The HRXL-MaxSonar-WRS is a low-cost, rugged ultrasonic snow depth sensor that is optimized for reliable snow depth

measurement. Sensor readings are optimized for snow measurement, ensuring accurate snow depth measurement

Applications and Uses

Features and Benefits

• Snow depth measurement

• Weather station monitoring

• Soft target detection

• Factory calibrated beam width

• All range outputs are active

simultaneously

• High acoustic sensitivity

Page 15

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PD12593i

MaxBotix^®Inc.

MaxBotix Inc., products are engineered and assembled in the USA.

Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

MB7364-MB7384 HRXL-MaxSonar^®-WRS^™Beam Pattern and Uses

The HRXL-MaxSonar-WRS is a low-cost, rugged ultrasonic snow depth sensor that is optimized for reliable snow depth

measurement. Sensor readings are optimized for snow measurement, ensuring accurate snow depth measurement

Applications and Uses

Features and Benefits

• Snow depth measurement

• Weather station monitoring

• Soft target detection

• Factory calibrated beam width

• All range outputs are active

simultaneously

• High acoustic sensitivity

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MaxBotix^®Inc.

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Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

Part Numbers

All part numbers are a combination of a six-character base followed by a dash and a three-digit product code.

Please review the following table for more information on the three-digit product code.

Note: Active part numbers listed on page 18.

-

M B 7 3 X 4

1

0

Base

Housing

Options

Wire

0

1

No Wire

Wire Attached

0

1

2

3

4

5

6

No Options (Bagged)

F-Option

0

1

2

3

4

5

6

7

8

Not Applicable

3/4” NPS WR

3/4” NPS WRC

Ultra Compact

Ultra Compact Flush Mount

1” NPS

P-Option

F-Option and P-Option

No Options (Trayed)

TTL (Bagged)

1” BSPP

TTL (Trayed)

30MM 1.5

Extended Horn

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HRXL-MaxSonar^®- WRS^™Series

The following tables display all of the active and valid part numbers for these products.

Active Part Numbers for MB7334

MB7334-100 MB7334-101 MB7334-110

MB7334-800 MB7334-801 MB7334-810

MB7334-111 MB7334-120 MB7334-121 MB7334-130 MB7334-131

MB7334-811 MB7334-820 MB7334-821 MB7334-830 MB7334-831

Active Part Numbers for MB7344

MB7344-100 MB7344-101 MB7344-110

MB7344-800 MB7344-801 MB7344-810

MB7344-111 MB7344-120 MB7344-121 MB7344-130 MB7344-131

MB7344-811 MB7344-820 MB7344-821 MB7344-830 MB7344-831

Active Part Numbers for MB7354

MB7354-100 MB7354-101 MB7354-110

MB7354-800 MB7354-801 MB7354-810

MB7354-111 MB7354-120 MB7354-121 MB7354-130 MB7354-131

MB7354-811 MB7354-820 MB7354-821 MB7354-830 MB7354-831

Active Part Numbers for MB7364

MB7364-100 MB7364-101 MB7364-110

MB7364-800 MB7364-801 MB7364-810

MB7364-111 MB7364-120 MB7364-121 MB7364-130 MB7364-131

MB7364-811 MB7364-820 MB7364-821 MB7364-830 MB7364-831

Active Part Numbers for MB7374

MB7374-100 MB7374-101 MB7374-110

MB7374-800 MB7374-801 MB7374-810

MB7374-111 MB7374-120 MB7374-121 MB7374-130 MB7374-131

MB7374-811 MB7374-820 MB7374-821 MB7374-830 MB7374-831

Active Part Numbers for MB7384

MB7384-100 MB7384-101 MB7384-110

MB7384-800 MB7384-801 MB7384-810

MB7384-111 MB7384-120 MB7384-121 MB7384-130 MB7384-131

MB7384-811 MB7384-820 MB7384-821 MB7384-830 MB7384-831

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Patent 7,679,996

HRXL-MaxSonar^®- WRS^™Series

After reviewing this datasheet, do you have any more questions?

We offer Technical Support on all of our products even if you purchased them through one of our many vendors

worldwide.

You can fill out a Technical Support form for assistance on a sensor here --> Technical Support

Not sure which sensor you need for your application?

We offer Sensor Selection Assistance, click the link here to fill out a form for support --> Sensor Selection Help

Looking for tutorials to help you get started?

Frequently Asked Questions about Our Sensors

We receive many questions about our products and services. This resource offers answers to common inquiries

we receive about our product lines and their application.

Fully Calibrated Beam Patterns

All of our sensors are factory calibrated to provide consistent beam patterns, detection zones, to fit into a wide

variety of applications. In our product lines, each model number comes with a different beam pattern that reflects

the sensitivity and the detection zone of how it sees a target. Additionally, we strive to maintain consistency be-

tween our finished products, and you will see little to no deviation between sensors of the same model. This al-

lows you to have confidence in your final application when using multiple sensors.

Understanding Range Readings

The success of an application may hinge upon knowing the exact location of a target. However, a sensor may

report one meter even if the target is not exactly one meter away from the sensor. Sensor specifications, such as

resolution, precision, and accuracy, help you to understand sensor performance.

How to Use Multiple Ultrasonic Sensors

This guide covers three ways to run your sensors in a Multiple Sensor environment and issues you may face.

Contact us now with any questions at sales@maxbotix.com or call +1-218-454-0766.

Please call during our preferred business hours of 8:00 am – 4:30 pm EST on Monday through Thursday and 8:00 am –

2:00 pm EST on Friday, or you may leave us a voicemail anytime.

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Patent 7,679,996


型号：	MB7344-820
厂家：	ETC
描述：	ULTRASONIC SENSOR HRXL-MAXSONAR
文件：	总19页 (文件大小：2484K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

MB7344-820 [ETC]

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