Frequently Asked Questions
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Can I use the WR sensors underwater? (Do you have an underwater sensor?)
Underwater use is a non-supported/non-warranty use of the MaxSonar-WR and WRC sensors. That being said, we have had many requests for this type of sensor. For this reason, we have provided the following informational article as a courtesy.
https://maxbotix.com/blogs/blog/underwater-ranging?_pos=1&_sid=cc157ee27&_ss=r
The range readings of my XL-MaxSonar are not accurate, is something wrong with my sensor?
The XL-MaxSonar-WR sensor is not calibrated to a distance so the distance will be relative with each sensor. This offset value can change from sensor to sensor. The offset value is considered to be acceptable up to +/- 10cm for production.
The sensors will report crisp 1cm resolution and will remain repeatable for each individual sensor. If a person requires this level of accuracy, our HR series of sensors have accuracy that is factory-matched providing a typical accuracy of 1% or better.
HRXL-MaxSonar-WR Products https://www.maxbotix.com/product-category/all-environments/hrxl-maxsonar-wr-products
SCXL-MaxSonar-WR Products https://www.maxbotix.com/product-category/all-environments/scxl-maxsonar-wrs-products
Can I use my sensor inside of a pipe?
Our sensors have limited operation inside a pipe. Below is a link to some information we have had from testing and research regarding pipe operation.
Link: https://www.maxbotix.com/tutorials5/ultrasonic-sensor-inside-pipe.htm
What is a cube corner reflector?
When you detect objects outside of the normal field of view of the sensor. You may be experiencing a problem with a cube corner reflector. A cube-corner reflector is any object outside the beam patterns we have characterized that can trap ultrasonic sound and reflect it back to the sensor. These are typically made up of 90-degree angles.
To test this, cover any objects at the range the sensor is reporting with a soft fleece blanket, even if the object is outside the beam pattern. When the sensor starts ranging normally, you can diagnose that a cube corner reflector is being detected. To keep the sensor from detecting this object, put a flat object across the object in a way that allows sound to reflect away from the sensor.
For detailed information on cube corner reflectors read through our following article on the topic.
Corner Reflectors Can Cause Surprise Clutter: https://www.maxbotix.com/tutorials2/cube-corner-reflectors.htm
I don't understand the MaxSonar beam patterns.
You may wish to read the following article on reading our beam patterns, but much of the same information is contained within this email.
Reading MaxSonar Beam Patterns: https://www.maxbotix.com/articles/reading-beam-patterns.htm
How can I use multiple sensors in the same system or near each other?
Ultrasonic Sensors output and receive sound information when taking a range reading. If multiple sensors are operational in the same environment this may cause one sensor to receive information sent by another sensor. To eliminate this, you need to chain the sensors together.
You can read through the following link to view chaining methods and crosstalk testing results.
Using Multiple MaxSonar Ultrasonic Sensors: https://maxbotix.com/blogs/blog/using-multiple-ultrasonic-sensors?_pos=1&_sid=3d4b90c9f&_ss=r
For users wishing to trigger sensor faster than the desired range cycle:
If you have sensors positioned ninety degrees from each other, you can typically start a ranging cycle every 33mS and not have sensor cross-talk. You continue this in a round-robin configuration.
How do I connect my sensor to a Raspberry Pi?
Please see the following link on connecting our sensors to a Raspberry Pi.
How do I connect my sensor to an Arduino?
Please see the following link on connecting our sensors to an Arduino.
Link: https://maxbotix.com/blogs/blog/arduino-guide?_pos=4&_sid=d5a9db3c6&_ss=r
My Pin 5 Serial output is incorrect or garbled?
Verify if your sensor outputs TTL or RS232 style serial data. Many of our sensors will output in the RS232 format but certain sensors do output in the TTL format.
The standard output is an ASCII capital “R”, followed by serial ASCII character digits representing the range in the sensors respective resolution, followed by a carriage return (ASCII 13). The baud rate is 9600, 8 bits, no parity, with one-stop bit.
How does temperature affect my sensor?
One aspect that can affect the range reading accuracy is improper temperature compensation. All of our high resolution (HR), self-cleaning (SC), and 4-20mA parts have internal temperature compensation present within the part,
Temperature compensation helps to compensate the range readings for the change in the speed of sound related to temperature. Without temperature compensation, range readings will have a more limited accuracy.
When operating in vertical columns of air, there can be widely varying temperatures in the air mass. As such, this may decrease the accuracy of the part as the temperature is measured within the part. To help account for a more accurate idea of the average temperature if the system we recommend placing an HR-MaxTemp, an external temperature sensor, halfway between your ultrasonic sensor and its target to provide a better idea of the environmental temperature.
HR-MaxTemp product page: https://www.maxbotix.com/Ultrasonic_Sensor/MB7955.htm
The XL-MaxSonar-WR sensor is not calibrated to a distance so the distance will be relative with each sensor. This offset value can change from sensor to sensor. The sensors will report crisp 1cm resolution and will remain repeatable for each individual sensor. If a person requires this level of accuracy, our HR series of sensors are Accuracy is factory-matched providing a typical accuracy of 1% or better.
Here is a link to the PDF on how to conduct Temperature compensation on the XL-MaxSonar sensor