Maxbotix Ultrasonic rangefinder lifetime?

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JeffersonBurch
 
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Maxbotix Ultrasonic rangefinder lifetime?

Post by JeffersonBurch »

At a rural location, I installed a Maxbotix Weather-resistant ultrasonic rangefinder -MB7092 (Adafruit product #1137) in the top of a large 8000 gal water tank. The sensor is in the airspace at the top of the tank at least 1 ft above the maximum water level. So, the sensor is always in the air space at the top of the tank. The sensor looks straight down and gives a great "distance to the water surface" measurement. In other words, I can monitor the tank's water level.

The sensor is screwed into a PVC fitting with the sensor wires safely enclosed inside a 1/2 PVC pipe. The pipe is attached to a nice flange mounting on the top of the tank with more PVC pipe outside the tank (with the sensor wire inside). The wire runs about 30' to a Beaglebone Black. The RS232 connection is routed through an RS232-to-TTL adapter from Lpgic Supply (http://www.logicsupply.com/cbb-ttl-232/).

The sensor sat idle in this configuration for an entire year with the sensor wires disconnected at the BBB end (i.e. the sensor was powered off). This past summer, I finally hooked it up to the Beaglebone Black and verified that I was receiving proper RS232 communication. The BBB provides 5V continuously to the sensor and the sensor makes continuous reading, sending the results back the RS232 cable.

The water level reading made sense. I left it in this mode "powered up" for about 6 weeks before getting back to the BBB programming. To my surprise, the sensor now appears dead. I've removed the sensor and installed a loopback wire and have verified that the RS232 converter and BBB are able to send and receive properly. I have not removed the sensor from the tank to inspect.

So, any ideas how long the Maxbotix sensor should last? I'm wondering if I should rework the circuit so that the BBB can control power to the sensor. That way, the sensor would only be powered up when needed (at most a few times a day when it is raining, less when it is not raining). Is continuous power the wrong way to connect this sensor?

The other failure hypothesis is high humidity and/or temperature in the top of the tank. The tank is at least 1/3 full of water but is in the full sun. The sensor is probably 6 inches down inside the tank from the tank's peak. It is hard to imagine that the air temperature inside the tank would exceed 65 deg C (the sensors rated maximum).

Thanks in advance!

- Jeff

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adafruit_support_bill
 
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Re: Maxbotix Ultrasonic rangefinder lifetime?

Post by adafruit_support_bill »

We don't have any data on long-term reliability of these sensors. You might want to contact Maxbotix to see if they have any statistics.
http://www.maxbotix.com/contact.htm

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tmwatson
 
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Re: Maxbotix Ultrasonic rangefinder lifetime?

Post by tmwatson »

I'm looking at your
Maxbotix Weather-Resistant Ultrasonic Rangefinder - MB7092 XL-MaxSonar-WRMA1 PRODUCT ID: 1137
for an app almost identical to JeffersonBurch's post.

Can you please confirm the manufacturer's part number for your product id 1137?
The mfr part number format from the data sheet is uploaded with this post.

In particular, does 1137 include the manufacturer's "P" option?
If not, could you make that version available?

Apologies if the mfr part number is on the website - I couldn't find it.

Thanks!!!
Attachments
Maxbotix manufacturer's part number format
Maxbotix manufacturer's part number format
XL-MaxSonar Mfr Part Number format.jpg (115.5 KiB) Viewed 748 times

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adafruit_support_bill
 
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Re: Maxbotix Ultrasonic rangefinder lifetime?

Post by adafruit_support_bill »

The model we carry is the standard oxidized aluminum surface - with no special coating options and no attached wires. The major electronics suppliers such as Mouser or Digikey will probably stock a wider selection of options.

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tmwatson
 
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Re: Maxbotix Ultrasonic rangefinder lifetime?

Post by tmwatson »

So that makes it a MB7092-100
?

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adafruit_support_bill
 
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Re: Maxbotix Ultrasonic rangefinder lifetime?

Post by adafruit_support_bill »

I think so. I will check to make sure.

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adafruit2
 
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Re: Maxbotix Ultrasonic rangefinder lifetime?

Post by adafruit2 »

look like it is XL-MaxSonar-WRMA1 does that look right?

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tmwatson
 
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Re: Maxbotix Ultrasonic rangefinder lifetime?

Post by tmwatson »

I can't find anything on the datasheet that ties to "-WRMA1" on your product page.
Which is why I asked and posted the mfr part number decoder ring from the datasheet.

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adafruit2
 
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Re: Maxbotix Ultrasonic rangefinder lifetime?

Post by adafruit2 »

thats the part # we use when we place the order :)

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tmwatson
 
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Re: Maxbotix Ultrasonic rangefinder lifetime?

Post by tmwatson »

Thanks for confirming! Appreciate your fast responses.

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