Author Topic: Anemometer question.  (Read 7585 times)

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Offline Skywatch

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Anemometer question.
« on: June 10, 2013, 11:41:34 AM »
Yesterday I bought an NRG wind set that in the future will be hooked up to the Davis Universal Anemometer Interface. After posting in other weather equipment about it and getting no response I'm assuming no one here knows anything about NRG sensors.

But I know some here have done tests on Davis anemometers. The instructions for the Davis Universal Anemometer Interface say how to hook up the anemometer NRG 40C but don't say how to hook up the NRG wind vane 200P.

So here's what I do know the NRG vane 200P has a maximum resistance of 10K ohms. Like the Davis anemometer the NRG 200P uses a potentiometer. I would like to know what the resistance is on the Davis anemometer? The NRG also states an operating voltage from 1-10 DC.

Some of y'all here also have some experience with the Universal Anemometer Interface? I know the manual states to connect black to black and blue to white on the anemometer. Which of the other 4 wires are the wind direction signal? The NRG 200P vane has 3 contacts.

I'd really appreciate some answers as I don't want to do anything foolish and fry the ISS.
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Offline johnd

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Re: Anemometer question.
« Reply #1 on: June 10, 2013, 12:20:54 PM »
Just download the 6410 data sheet from Davis. 6410 pot is 20K.
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Offline Skywatch

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Re: Anemometer question.
« Reply #2 on: June 10, 2013, 01:40:16 PM »
I Spoke with Davis and they said to use the green and yellow wires. So the Davis output is 20 ohms. The NRG wind sensor uses 10 ohms.

Forgive me for my lack of knowledge. But would a 10K ohm 1/2 watt resistor like those sold at RadioShack work or would this add to the resistance? I really don't know how this stuff works.

Simply put, Davis direction output is 20K ohms at 3 volts. The NRG #200P wind vane is 10K ohms with a working voltage of 1-10 volts. How can I modify the NRG vane's output to be compatible with the wind direction output? I need some of you tech guys.
« Last Edit: June 10, 2013, 02:29:13 PM by Skywatch »
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Offline dalecoy

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Re: Anemometer question.
« Reply #3 on: June 10, 2013, 02:46:54 PM »
I could easily be wrong, but it seems to me that the Davis "Universal Anemometer Interface" only interfaces an anemometer - not a wind vane, too.

Offline Skywatch

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Re: Anemometer question.
« Reply #4 on: June 10, 2013, 04:02:05 PM »
That's what I thought. But I called them today and they said something about connecting the green and yellow wires. the Davis vane uses 1-20K ohms while the NRG 1904 vane is 1-10K ohms. I'm wondering If I added a 10K ohm resistor if that would fix it or further effect the performance? Is there a way I could amplify the Ohms to match the output that the Davis ISS recognizes?
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Offline dalecoy

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Re: Anemometer question.
« Reply #5 on: June 10, 2013, 04:17:20 PM »
... the Davis vane uses 1-20K ohms while the NRG 1904 vane is 1-10K ohms. I'm wondering If I added a 10K ohm resistor if that would fix it or further effect the performance? ...

No, that wouldn't fix it - regardless of how you hooked up the resistor.

Is there a way I could amplify the Ohms to match the output that the Davis ISS recognizes?

Not as a practical matter in this application. 

Offline Skywatch

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Re: Anemometer question.
« Reply #6 on: June 10, 2013, 04:27:05 PM »
So should I just hook the yellow and green up as mentioned over the phone and hope for the best? In the Davis spec chart for their anemometer it specifies 10K ohms represents 180 degrees or south. Does this mean I'll only get half the of the wind direction scale?
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Offline johnd

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Re: Anemometer question.
« Reply #7 on: June 10, 2013, 04:48:43 PM »
So should I just hook the yellow and green up as mentioned over the phone and hope for the best? In the Davis spec chart for their anemometer it specifies 10K ohms represents 180 degrees or south. Does this mean I'll only get half the of the wind direction scale?
Forget using the NRG wind vane is the only practicable advice I'm afraid. There's no simple way of making it compatible with a VP2 ISS AFAIK.
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Sorry, but I don't usually have time to help with individual issues by email unless you are a Prodata customer. Please post your issue in the relevant forum section here & I will comment there if I have anything useful to add.

Offline dalecoy

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Re: Anemometer question.
« Reply #8 on: June 10, 2013, 05:12:24 PM »
10K ohms represents 180 degrees or south. Does this mean I'll only get half the of the wind direction scale?

Yes.

In theory, it might be possible to replace the potentiometer - but I'm guessing you wouldn't want to try that.

Offline Skywatch

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Re: Anemometer question.
« Reply #9 on: June 10, 2013, 06:12:03 PM »
I just took a look at the R.M. Young Wind Monitor manual and Graculus is right. The R.M. young does use the similar potentiometer. 10K ohms analog DC current. And also both sensors have a 3 wire hook up. I'm thinking of trying this. It's will probably be a few weeks before I purchase the UAI. So it appears both sensors have the same power input. Thanks Graculus!
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Offline rdsman

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Re: Anemometer question.
« Reply #10 on: June 10, 2013, 06:31:43 PM »
The manual for the RM Young 05103 shows the following terminal strip connections:

1.  Earth Ground
2.  Wind Speed Reference
3.  Wind Direction Reference
4.  Wind Direction Signal
5.  Wind Direction Excitation
6.  Wind Speed Signal

The Davis Universal Anemometer Interface manual shows the following Davis cable colors for the connections:

2.  Black (WSR)
3.  Red (WDR)
4.  Green (WDS)
5.  Yellow (WDE)
6.  Blue (WSS)

Using the NRG Symphonie wiring guide, we should come up with something like this:

NRG 200P (Red) to Davis (Yellow)
NRG 200P (White) to Davis (Green)
NRG 200P (Black) to Davis (Red)

If is doesn't read correctly, reverse the NRG 200P Red and Black connections - it's just a pot!

« Last Edit: June 10, 2013, 07:53:39 PM by rdsman »
Ray

Offline Skywatch

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Re: Anemometer question.
« Reply #11 on: June 10, 2013, 06:43:42 PM »
Awesome. This is why I love WXforum, Y'all are hero's. Solving problems and saving the day.
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Offline dalecoy

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Re: Anemometer question.
« Reply #12 on: June 10, 2013, 07:40:20 PM »
Awesome. This is why I love WXforum, Y'all are hero's. Solving problems and saving the day.

Looking at the excellent description of the circuit in   http://www.lexingtonwx.com/anemometer/
I see how this applies.  Johnd and I were answering "how to make a 10K potentiometer into a 20K potentiometer" - which isn't practical.  However, the circuitry is such that (within reason) it is independent of the total resistance. 

Please do remember to come back and confirm that it actually works.  That might help other folks in the future.
« Last Edit: June 10, 2013, 08:03:52 PM by dalecoy »

Offline Skywatch

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Re: Anemometer question.
« Reply #13 on: June 10, 2013, 09:18:09 PM »
Awesome. This is why I love WXforum, Y'all are hero's. Solving problems and saving the day.


Please do remember to come back and confirm that it actually works.  That might help other folks in the future.

Will do!  :grin:
I live in an apartment and for the moment am not a home weather watcher.

I am a storm chaser.

Offline dalecoy

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Re: Anemometer question.
« Reply #14 on: June 10, 2013, 09:19:30 PM »
From the reference:

"yellow = direction excitation  This is an excitation pulse sent from the SIM to the anemometer and is applied to the cw terminal of the potentiometer."

If it's a pulse, then the power requirement would be more reasonable (even though twice as much as for a 20K pot).

Offline Skywatch

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Re: Anemometer question.
« Reply #15 on: June 10, 2013, 09:35:24 PM »
It will probably be the end of the month when I can afford the UAI. But I do plan to post the end results. This week I'm going to Lowes to buy some conduit to make a cross arm. In the center will be a junction box to access the wires.

PS does anyone know if there's a standard for distance between the anemometer and wind vane when mounting on a cross arm in the same manner as e.g. Heath Kit or Fine offset's wind sensors? I'm thinking something like 6-12" or does it make a difference? I want the sensors to be accurate and not interfering with each other.
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Offline DaleReid

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Re: Anemometer question.
« Reply #16 on: June 10, 2013, 09:38:59 PM »
The Lexington site indicates that the reed switch is excited by 3 volts, which is the same as going to the potentiometer.

If it is a 10k pot, then 0.3 ma is drawn, and a 20k pot would only bring that down to 0.15 or 1/2 the current.  And if the voltage is indeed excited by a pulse, then the draw will be less, but not sure how the ISS would know when to pulse it to catch all the revolutions of the wind cups if both the vane and cups are excited by the same supply line.

In general, it would seem that there were several ways to do direction.  Grey encoding like the Heathkits do, with only 16 points of the compass, vs. a potentiometer, which itself has two easy ways to give direction.  One is to give the potentiometer a known voltage, and if the pot is a known value, 'look' for a returned voltage that is referenced to a calibrated direction, that is at 180 degrees, if you sent 3 volts out to the pot, then you'd expect 1.5 volts back.

The other, somewhat more elegant way, is to not give a flying care about what the pot's resistance was (other than to take into account drain and damage if too much current goes through the pot) but to look at the ratio of the voltage coming back.  If the pot is at 180 degrees and you send up 5.345 volts to a 16,750 ohm pot, then you get half the voltage back at 180 no matter what the potentiometer really is for resistance.  This method seems a bit more self correcting.  

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Offline Skywatch

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Re: Anemometer question.
« Reply #17 on: June 11, 2013, 01:07:23 PM »
The brown UPS truck just brought me the anemometer. now waiting for the wind vane and I'll begin building the cross arm for the sensors.
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Offline Skywatch

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Re: Anemometer question.
« Reply #18 on: June 11, 2013, 05:10:45 PM »
Got this email from NRG

Thank you for your message.

 

The vane has three terminals:

 

·         + for excitation

·         - for ground, or DC return

·         Signal out

 

The vane has a potentiometer based output. It requires a DC excitation of 1 to 15 VDC to produce a ratiometric output voltage based on position.

 

As far as a two wire application, I haven’t heard of a logger that would expect a changing resistance value unless it was acting as a current source; this type of interface is not recommended for use with the 200P.

 

I hope that helps. Please let me know if you have any questions.


 Best regards,

Dave

Looks like you guys were right. If this is the case the vane should wire in to the UAI
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Offline Skywatch

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Re: Anemometer question.
« Reply #19 on: June 12, 2013, 08:51:04 PM »
I got another email today from NRG.



As long as

 

·         “WDR” stands for “wind direction return”

·         “WDE” stands for “wind direction excitation”

·         “WDS” stands for “wind direction signal”

 

Then the instructions look perfect!

 

Please let me know if you have any questions.

 

Best regards,

Dave


I also got the 1904 vane #200P from the big brown truck today. I'm going to do some research on the color codes for the #200P vane. Mine for some reason doesn't have color coded contacts. So I'm going to track down the color schematics.

Meanwhile someone on eBay is selling the steel anemometer arms for the Oregon Scientific WGR800 sensors. The pipe diameter on those fits perfectly with the fitting on the underside of the NRG sensors. Then I'm going to find a tee piece at Lowes or Home Depot to join the 2 arms together creating the cross beam for the sensors.
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Offline Skywatch

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Re: Anemometer question.
« Reply #20 on: June 13, 2013, 12:13:30 PM »
Tomorrow I get paid. I'm going to place the order for the UAI from Archer Trading Post and hopefully set it up next week. I'll post the end results.
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Offline rdsman

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Re: Anemometer question.
« Reply #21 on: June 13, 2013, 12:39:48 PM »
Quote
I also got the 1904 vane #200P from the big brown truck today. I'm going to do some research on the color codes for the #200P vane. Mine for some reason doesn't have color coded contacts. So I'm going to track down the color schematics.

The colors codes are derived from the Symphonie wiring diagram:

http://www.nrgsystems.com/FileLibrary/2b2076e33aa2495b8544850809ceb24c/SymphoniePLUS%20Sensor%20Connection%20Instructions.pdf

Hope this helps......
Ray

Offline Skywatch

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Re: Anemometer question.
« Reply #22 on: June 19, 2013, 12:19:33 PM »
For curiosity purposes I found this vane wiring chart. http://forum.nrgsystems.com/forums/storage/30/212/VaneWiring.pdf
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Offline Skywatch

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Re: Anemometer question.
« Reply #23 on: June 20, 2013, 04:50:01 PM »
Just got an email from Ryan saying the UAI is being drop shipped directly from Davis. It should arrive on Saturday. That will be the moment of truth. I'll post the results.

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Offline Skywatch

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Re: Anemometer question.
« Reply #24 on: June 26, 2013, 12:32:49 PM »
I just pulled by station's data from Wunderground. in about an hour the USPS truck will bring me my UAI. Today will be the moment of truth. I'll keep ya'll posted.
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