WXforum.net
Weather Station Hardware => Davis Instruments Weather Stations => Topic started by: Skywatch 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.
-
Just download the 6410 data sheet from Davis. 6410 pot is 20K.
-
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.
-
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.
-
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?
-
... 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.
-
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?
-
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.
-
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.
-
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!
-
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!
-
Awesome. This is why I love WXforum, Y'all are hero's. Solving problems and saving the day.
-
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.
-
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:
-
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).
-
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.
-
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.
-
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.
-
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
-
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.
-
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.
-
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......
-
For curiosity purposes I found this vane wiring chart. http://forum.nrgsystems.com/forums/storage/30/212/VaneWiring.pdf
-
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.
-
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.
-
The moment we've (I included) have waited for. The UAI arrived. Spent this afternoon hooking it up.
Yes the Red Green and Yellow wires hooked up as instructed sure enough it works. Using the North indicator on the vane sensor it correctly recognizes North and south and everything in between. Not sure why Davis didn't list this in the manual maybe simply they didn't test it. But I have Confirmed the vane does work.
To simplify Red Green Yellow Sorry if ya'll can't read it. The color it's self should be enough.
_ Signal +
Okay now for my thoughts on the sensors. I am impressed with the build quality on the NRG sensors. The wind vane is much more sensitive to wind than the VP2 vane or at least the old one. The anemometer from my perspective is about the same sensitivity as the Davis. Not too disappointing being the NRG anemometer is less finicky than the Davis to a slight tilt of the pole which is not visible to the naked eye but to a carpenters level but only slightly off. Goes for the vane too. This used to be a problem with the Davis to the point I had to slightly bend the arm on the Davis anemometer to get it to be balanced.
After reading more on the NRG anemometer I find they use Teflon bearings which are said to last many times longer than normal steel ball bearings. Another thing I like is the NRG anemometer does not use reed switches or photo gates. Instead uses a 4 pole magnet and coil to general it's own sine wave AC signal. So it produces it's own electricity in a pulse. The UAI reads the pulse which is dependent on the wind speed and translates it into a signal that the Vantage Pro2 ISS recognizes.
No reed switches to fail after years of use and Teflon bearings which last forever without wear and tear.
I've got a friend in Washington State who lives on the coast and collects the vintage Maximum Maestro wind instruments. Some of which range from 20-40+ years old with original anemometers which are the same ones NRG uses. And after 40+ years of salt, abuse, and neglect on the roof they're still as sensitive to wind as day one and still report wind speed without skipping a beat.
What I have learned about the history behind the anemometer is NRG is not the original manufacture of that anemometer. I'm not certain of who the original manufacture is but NRG was founded in the early 80's. the 40C anemometer was designed the same year Davis Instruments was founded in 1963. I'm guessing the original manufacture was Maximum but I don't know that for sure. So the wind sensors do have a long and positive reputation.
Anyway I'm happy to be able to contribute to the WXforum community. I hope my findings helped.
Sorry I couldn't get pictures of the process. My phone is broken and that's my only camera.
-
Not sure who's still reading this. But I'm a bit curious about the solar and battery for the UAI. I'm guessing this provides additional power to the UAI for communicating to the sensors and ISS. But as it's not a transmitter how do you know if the battery is low?
-
Some more comments about the NRG anemometer. After watching it for a few days I've actually noticed it is more sensitive to the wind than the Davis even though manually spinning the cups it seems the same. My guess on this is the larger cups may respond better to wind than the smaller cups Davis uses.
Another thing I've noticed is the rotation seems to be more relevant to the wind speed. On the Davis anemometer the rotation was initiated by the wind but momentum kept the cups spinning for a few seconds. I have to wonder is most of the wind speed reading was the actual wind or if it was the left over momentum. The NRG if the wind blows the cups spin. If the wind stops the cups stop and don't continue to spin due to momentum. This to me is a huge plus. I feel the wind readings are more accurate because momentum is minimized. This means the wind speeds are mostly wind related and not momentum related.
A+ for NRG!
-
I rigged up a cheap web cam to snap a photo of the new anemometer installation. And I say it's a cheap camera because of the poor image quality. But anyway at least is a photo. Here's a picture of the installation. When I get my phone fixed I'll post some better images.
-
Some more comments about the NRG anemometer. After watching it for a few days I've actually noticed it is more sensitive to the wind than the Davis even though manually spinning the cups it seems the same. My guess on this is the larger cups may respond better to wind than the smaller cups Davis uses.
Another thing I've noticed is the rotation seems to be more relevant to the wind speed. On the Davis anemometer the rotation was initiated by the wind but momentum kept the cups spinning for a few seconds. I have to wonder is most of the wind speed reading was the actual wind or if it was the left over momentum. The NRG if the wind blows the cups spin. If the wind stops the cups stop and don't continue to spin due to momentum. This to me is a huge plus. I feel the wind readings are more accurate because momentum is minimized. This means the wind speeds are mostly wind related and not momentum related.
A+ for NRG!
Hi Skywatch,
I have several NRG 40's that I have been testing with the Davis as well.
I have a bit of an issue I was going to see if you have run into.
Im seeing wind readings that are somewhat high I believe.
I have the Davis and the NRG on the same pole testing both speeds with two different Davis stations and for example I got a 31mph gust on the NRG, and 24 mph on the Davis, and I think 22-25mph at KSEA which is just 1.3 miles as the crow flies from my station.
Have you compared speeds? I think 31mph might have been a bit high, but I have tested 4 different NRG 40's that I have sitting around, and they all give the same readings when I use a simple house fan to test for speed.
I actually took down my RMyoung 05103 because I was getting just slightly LOWER speeds than on the Davis, 31vs 29mph for example, now the NRG comes in and is blowing the Davis out of the water, by 30% at time 25% or slightly more at peak winds.
Not sure what to make of this , I have tried all the different cup settings on the Davis also, OTHER< SMALL< LARGE
Any experience with this?
Thx