Author Topic: Anemometer - Frozen at 5 N (mostly?)  (Read 840 times)

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Offline SpartanWX

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Anemometer - Frozen at 5 N (mostly?)
« on: March 31, 2019, 02:47:10 PM »
Greetings all,
Looks like there is a spate of anemometer anomalies lately.  A week or so ago my wireless Davis VP2 with wired anemometer (replaced 6 months ago due to failed reed switch) has frozen at 5.  The odd thing is that once every 20 or so readings it will move from there, but only to 9 or 360, and only for a moment.

So far I have checked the splices which were clean, dry, and in excellent visual condition, checked and clean the connection in the ISS, and reset both the console and ISS.

It is weird to me because it is not a dead fault.  My logical next step is to redo the splice, which is a minor pain in the ass. Short of that fixing it, I presume it's a hardware defect. 

Is there anything I could be missing?

The wind vane is spinning freely.  And I'm confident it's not the set screw (even though I have not checked it) due to the fact the it sits pretty stable at 5 with intermittent forays to 9 or 360.

Offline SpartanWX

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #1 on: March 31, 2019, 02:56:00 PM »
Here's a picture of when the fault occurred originally 2 weeks ago:
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And another showing a weird period where it went up to 24 for a couple of hours before falling back down to 5:
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Offline miraculon

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #2 on: March 31, 2019, 06:06:19 PM »
Please see this thread: http://www.wxforum.net/index.php?topic=36402

Since you have a wireless VP2, it tends to point to the anemometer cable. (the wired VP2 had an unusual issue related to ground or common-mode)

In your case, please look at this section:

http://www.wxforum.net/index.php?topic=36402.msg373624#msg373624

This comes from http://www.lexingtonwx.com/anemometer/

Wiring errors:
yellow wire open causes a north indication
green wire open causes a north indication

red wire open causes a north indication and prevents wind speed from being indicated
black wire open prevents wind speed to be indicated
yellow to green shorted causes a north indication
yellow to red shorted causes a north indication
green to red shorted causes a north indication

black to yellow shorted, wind speed zero
black to green shorted, wind speed zero and direction erratic
black to red shorted, wind speed zero, intermittent short causes wind speed error

Greg H.






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Online johnd

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #3 on: April 01, 2019, 03:47:22 AM »
No wireless repeater involved is there? (Unlikely I know, but a repeater can cause this sort of symptom.)
Prodata Weather Systems
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Offline bazzalight

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #4 on: August 23, 2019, 04:15:52 AM »
I have been experiencing a similar issue over the last 4 weeks (see attached.  I have done the cable checks including splicing out the cable right at the head unit. If I put in a normal 20 K potentiometer then I have no drop outs to 0/360 deg). The only correlation I can see is temperature (below 20 C). Unit is only 12 months old..  not overly impressed with the Davis design with mechanical forces applied directly to the Potentiometer nor the ability to service the POT.....I think I will  build my own with separate bearings and a flexible joint to the POT.

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« Last Edit: August 23, 2019, 04:18:47 AM by bazzalight »

Online PaulMy

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #5 on: August 23, 2019, 09:15:02 AM »
Quote
The wind vane is spinning freely.  And I'm confident it's not the set screw (even though I have not checked it) due to the fact the it sits pretty stable at 5 with intermittent forays to 9 or 360.
A bit late to comment on this but I had a similar experience this spring with my May 2018 new VP2 Plus ISS, vane spinning as expected but long periods 0 wind direction, and occasional seeming ok.

Then as we were moving to a new house I took down the VP2 along with the anemometer pole and, as cautious as I tried to be, it dropped and saw the vane was off.  D*** I said, I've broken it.  Checked it and everything else seemed okay.  On closer inspection the vane and the rest of the anemometer seemed ok.  That is when I found the set screw had not been tightened.  Got the Allen wrench to tighten it and no problems since.

Enjoy,
Paul
Davis Vantage Pro 2 Plus 24-FARS Wireless
Envoy/USB DataLogger/Cumulus v.1.9.4   -   Vue Console/WiFiLogger/CumulusMX
Komoka, ON  Canada
www.komokaweather.ca   www.komokaweather.com   www.komokaweather.com/weather28/  
www.komokaweather.com/pws/index.php
Blitzortung Station #1076 www.lightningmaps.org/blitzortung7/america/index.php?bo_page=statistics&bo_show=network&lang=en&bo_station_id=969


Offline bazzalight

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #6 on: September 14, 2019, 12:06:12 AM »
further update on my post of Aug 23.  I checked all the cable again, and verified the grub screw on the vane was secure. Errors still persisted and once again it seem to correlate to temperature dropping below 18 - 20 C.
So....  I  did end up building my own vane and so far the problem has gone away. Hopefully it will last long enough till the anemometer fails and I can justify buying a complete Davis vane and anemometer assembly.

Details of my build are at https://www.thingiverse.com/thing:3859676

regards
Barry C

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Offline Old Tele man

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #7 on: September 14, 2019, 02:04:57 PM »
WHEN will Davis abandon ANALOG and go DIGITAL for anemometer data? A simple 360-degree-by-one degree resolution 'pulsed' LED encoder would be much better.
« Last Edit: September 14, 2019, 02:07:35 PM by Old Tele man »
SYS: Davis VP2 Vue/WL-IP & Envoy8X/WL-USB;
DBX2 & DBX1 Precision Digital Barographs
CWOP: DW6988 - 2 miles NNE of Cortaro, AZ
WU - KAZTUCSO202, Countryside

Offline waiukuweather

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #8 on: September 14, 2019, 03:53:30 PM »
woa at building your won vane!  :shock:

Offline dalecoy

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #9 on: September 14, 2019, 04:17:20 PM »
WHEN will Davis abandon ANALOG and go DIGITAL for anemometer data? A simple 360-degree-by-one degree resolution 'pulsed' LED encoder would be much better.

That would take a *LOT* more power.

Offline Old Tele man

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #10 on: September 14, 2019, 06:19:38 PM »
WHEN will Davis abandon ANALOG and go DIGITAL for anemometer data? A simple 360-degree-by-one degree resolution 'pulsed' LED encoder would be much better.

That would take a *LOT* more power.

Not when both the transmitting LED and receiving PHOTO sensor are "pulsed," as in '...turned ON for a reading and then OFF until the NEXT reading is to occur' which is an intrinsic benefit of digital circuitry over analog circuitry. With pulsed operation you suddenly draw power for an instant and then wait/sleep for a quite awhile longer which lowers total power quite low.
« Last Edit: September 14, 2019, 06:23:38 PM by Old Tele man »
SYS: Davis VP2 Vue/WL-IP & Envoy8X/WL-USB;
DBX2 & DBX1 Precision Digital Barographs
CWOP: DW6988 - 2 miles NNE of Cortaro, AZ
WU - KAZTUCSO202, Countryside

Offline dalecoy

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #11 on: September 14, 2019, 07:43:02 PM »
WHEN will Davis abandon ANALOG and go DIGITAL for anemometer data? A simple 360-degree-by-one degree resolution 'pulsed' LED encoder would be much better.

Not when both the transmitting LED and receiving PHOTO sensor are "pulsed," as in '...turned ON for a reading and then OFF until the NEXT reading is to occur' which is an intrinsic benefit of digital circuitry over analog circuitry. With pulsed operation you suddenly draw power for an instant and then wait/sleep for a quite awhile longer which lowers total power quite low.

Please help me out by saying what the sensor would be "reading".  Something that has 360 different patterns depending on what position the wind vane is in? 

Online badhairday

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #12 on: September 14, 2019, 08:04:46 PM »
Very nice work Barry!

I was also impressed with what this guy did.  https://www.instructables.com/id/Accurate-Wireless-Weather-Vane/.  After about 20 years of DIY weather stations and the repairs, I opted to buy a VP2.

Chris

Offline bazzalight

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #13 on: September 14, 2019, 09:21:08 PM »
Thanks Chris,

Yes like you I opted for the VP2 after spending many years with lesser quality products - the Davis still stands out for its low power needs and the wireless interface.  I did baulk at the price of additional sensors so I also built my own Solar sensor and interfaced that into the ISS.

regards
Barry

Offline Old Tele man

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #14 on: September 15, 2019, 05:35:33 PM »
WHEN will Davis abandon ANALOG and go DIGITAL for anemometer data? A simple 360-degree-by-one degree resolution 'pulsed' LED encoder would be much better.

Not when both the transmitting LED and receiving PHOTO sensor are "pulsed," as in '...turned ON for a reading and then OFF until the NEXT reading is to occur' which is an intrinsic benefit of digital circuitry over analog circuitry. With pulsed operation you suddenly draw power for an instant and then wait/sleep for a quite awhile longer which lowers total power quite low.
Please help me out by saying what the sensor would be "reading".  Something that has 360 different patterns depending on what position the wind vane is in?

Imagine this as a 10-bit Gray Code sensor where the one's & zero's are *read* at the normal ISS sample rate then the illuminating LED and the photo-cell sensing device are de-powered until the next ISS sample time occurs:  https://www.youtube.com/watch?v=oc5hIxdCMZ0

With no physically-contacting parts (ie: resistive potentiometer), rotational friction is reduced to bearings only...and...*pulsed* illumination/sensing minimizes power consumption (ie: pulse-width modulation). The only new electronic device needed is a 10-bit parallel input to serial-output converter chip, like any USB converter uses.

Gray code eliminates "inter-digit' bit ambiguities where both OLD and NEW bit readings overlap because with Gray coding only one bit changes per increment. Because they don't commonly make "odd-numbered" 9-bit encoders/decoders, a 10-bit encoder is needed to achieve 1-bit per 1-degree resolution:

000-degrees: 0000000000.
359-degrees: 0101100111.

More info:

page 40: https://support.automationdirect.com/docs/absolute_encoders.pdf
Gray code video: https://www.youtube.com/watch?v=HlYLhsK7eOA

« Last Edit: September 15, 2019, 08:44:45 PM by Old Tele man »
SYS: Davis VP2 Vue/WL-IP & Envoy8X/WL-USB;
DBX2 & DBX1 Precision Digital Barographs
CWOP: DW6988 - 2 miles NNE of Cortaro, AZ
WU - KAZTUCSO202, Countryside

Offline dalecoy

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #15 on: September 15, 2019, 05:52:06 PM »
OK.  Got it.  THANKS!

Offline mcrossley

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #16 on: Yesterday at 02:49:04 AM »
WHEN will Davis abandon ANALOG and go DIGITAL for anemometer data? A simple 360-degree-by-one degree resolution 'pulsed' LED encoder would be much better.
When they are cost effective? From my experience they are not cheap - especially for astronomy telescope mounts where you need arcsec resolution = $000+
I imagine a 10 bit encoder is going to be $00+ ?
Mark

Offline rdsman

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Re: Anemometer - Frozen at 5 N (mostly?)
« Reply #17 on: Yesterday at 11:03:59 AM »
Heck, even my old Vue used a magnetic position sensor for wind direction.  Quite similar to this:

https://www.mouser.com/productdetail/ams/as5510-dsot?qs=qEcPHXRbv51phqda3LiLLQ%3D%3D

(The wind vane shaft is magnetized.)

« Last Edit: Yesterday at 11:08:17 AM by rdsman »
Ray