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Lights_2_medium
Aug 25, 2012 11:30pm
156 posts

Does anyone know if there is such a thing as a web based weather station which can send the data to SEG? I am currently waiting for my eight temperature probes for the GEM. I plan on deploying two of them outside. One will be in my garage, and the other will be placed on the exterior of the home to detect the actual ambient temperate at my residence. Now, what I also wanted to do was to be able to see actual weather related data from some web based weather station.

I would like to know if any of the 999999999999 websites can send their data in SEG format? Also, if anyone is using a stand alone weather station please do let me know the brand, model number, along with what are the capabilities your unit has. If I decide to go with more hardware, I would prefer a well known brand that is a tried and true performer. I am trying to balance cost vs value so please do keep that in mind. Much Thanks P.S. What is the story with the formating with this site?? Why does it jumble up all of my paragraphs?? Teken . . .

 
Icon_missing_medium
Sep 4, 2012 9:34am
16 posts

I had a similar issue so I wrote a little Google App Engine piece that gets data from a local WUnderground (Weather Underground) and posts it to SEG (Temperature, Humidity, Wind, Rain).  In my case there are two realitively close WUnderground stations for me to choose from.

The single App Engine instance could certainly handle additional load and stay in the free tier, though I should probably move to the new WUnderground API.  It works as is today from the XML page for a WUnderground site.  The only tricky part of the code is the rainfall, where I used a quick memcache to calculate the delta between reads.

Happy to discuss further, Or you could simply take the idea and build your own.

 
Lights_2_medium
Sep 4, 2012 11:31am
156 posts
I would love more details about what you have been able to do! I would appreciate any help in this you could provide. Much thanks! Teken
 
Lights_2_medium
Sep 13, 2012 4:51pm
156 posts
Gdruce, Anymore information??
 
Icon_missing_medium
Sep 16, 2012 12:16pm
16 posts

Hi Teken,

Sorry about the slow reply, been distracted with my day job.

Concept

1. Create a new Device for your weather with a node called weather (in the example post below)

2. Create a collection of streams based on the information available from Wunderground.  I used:

  • temperature
  • relative_humidity
  • wind_speed
  • wind_direction
  • wind_gust
  • barometric_pressure
  • dew_point
  • rainfall

3. Retrieve the XML formatted data from a Wunderground station eg http://api.wunderground.com/weatherstation/WXCu...

Note this should be updated to use their proper API....which while being very similar is currently a job the holidays

4. Reformat it into a SEG Stream like

(site xxxxxxxxxxxxx (node weather ? (temperature 14.1)(relative_humidity 76)(wind_speed 0.0)(wind_direction 90)(wind_gust 0.0)(barometric_pressure 998.9)(dew_point 9.9)(rainfall 0.0)))

where xxxxxxxxxxxxxx is you site ID.

Trickiest part is Rainfall needs to the the rainfall delta, ie the rainfall since the last measurement.

5. Post this data to SEG and Bob's your uncle.

6. Rinse and repeat from step 3 as often as is required.  I do 10 minutes.

Building Blocks

In my case I created a simple Servlet that runs on Googles wonderful App Engine environment.

Servlets can be triggered on a regular basis by a cron job like configuration file.

For the 10 minutes run you should only ever have a single instance which should keep you in the free tier.

Ideas

The slowest part of all of this is establishing the HTTP connections to Wunderground to get data and SEG to post data, since over 10 mins you don't want to be holding them open.  

In theory a single AppEngine instance could host multiple stations as the incremental cost of second requests over open connections would be low.  Code doesn't yet support this and pragmatically would probably require the sharing of your site key which you may or may not be willing to do.

Anyway. hope this helps.

 

 
Samotage_300_medium
Sep 16, 2012 9:21pm
555 posts

Nice post Glenn!

As an aside I've solved that 16 channel switching problem and have FTDI cables in stock now.

Sam, @samotage

 
Icon_missing_medium
Oct 12, 2012 8:53pm
4 posts

Glenn and Phil  - Thanks much for the great idea!  - I'm "inprogress" on a VB script that's run locally from a server, that hits the WUG site, and uses several local PWS, as well as a local airport - I'm still in debug, but I'll be willing to share for those that want to run VB script locally, versus PHP..   But this brings me to a question about a few "weather related" stream data types - I see there is a already a "UNIT" of Temperature in both C & F.  But some of the other weather units are just metric - Specifically

WindSpeed and Gust Speed - currently in m/s - Can we add mph?

Rainfall - currently in mm - Can we add inches?

Baro Pressure - currently in hPA - Can we add pressure in Millibars and/or Inches

I'm not entirely clear on where/how units are used, but at least from a documentation standard, and given that Temp is available in english/metric units, the above seemed like a good idea.   

Let me know if I'm off base here.

Thanks - GFA

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