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+--- Forum: Scripting (https://forum.logicmachine.net/forumdisplay.php?fid=8)
+--- Thread: Wind speed close shutter (/showthread.php?tid=2458)
Wind speed close shutter - MantasJ - 08.02.2020
Hello,
I have a task where I need to get current wind speed and if it is above certain number (in this case 12 meters/second), the shutter in outside would close. I wanted to do this from KNX weather station, but it seems it doesn't provide actual wind speed accurately, so my guess is I should propably use some API service.
I have tried this script:
Quote:require('socket.http')
forecast = {}
function parsetag(parser, tag, attributes)
if tag == 'time' then
table.insert(forecast, {})
elseif tag == 'symbol' then
forecast[ #forecast ].symbol = attributes.name
elseif tag == 'precipitation' then
forecast[ #forecast ].precipitation = attributes.value
elseif tag == 'windDirection' then
forecast[ #forecast ].wind_direction = attributes.code
elseif tag == 'windSpeed' then
forecast[ #forecast ].wind_speed = attributes.mps
elseif tag == 'temperature' then
forecast[ #forecast ].temperature = attributes.value
elseif tag == 'pressure' then
forecast[ #forecast ].pressure = attributes.value
end
end
url = 'http://www.yr.no/place/Lithuania/Klaipeda/Klaipėda/varsel.xml'
data, err = socket.http.request(url)
if data then
require('lxp').new({
StartElement = parsetag
}):parse(data)
log(forecast)
else
alert('Fetch failed: ' .. tostring(err))
end
But it returns some odd numbers which doesn't really match the forecast from elsewhere, but then I thought maybe I just don't understand what it returns. So how data is returned? The table has 36 entries and I though maybe it is 35 from days starting from first entry (today) forecast, or no? Maybe it is some king of interval based?
Thank You
RE: Wind speed close shutter - admin - 08.02.2020
Try using hourly forecast xml: https://www.yr.no/place/Lithuania/Klaipeda/Klaip%C4%97da/forecast_hour_by_hour.xml
Wind speed is specified in miles per hour for some reason so a bit of extra conversion is required.
RE: Wind speed close shutter - Joep - 08.02.2020
There are better api's available using JSON. But first of all i would like to say that for this purpose it's better to meassure at the side where your shutter is installed. Specially if you use it for a professional installation side. Some weather API's can be found here. https://superdevresources.com/weather-forecast-api-for-developing-apps/
Below an example we use with a Dutch weather API in JSON.
require('ssl.https')
require('json')
city = 'Amsterdam'
data = ssl.https.request('http://weerlive.nl/api/json-10min.php?locatie=' ..city)
datatable = json.pdecode(data)
datatable = datatable['liveweer'][1]
--log(datatable)
temp = datatable.temp --actuele temperatuur
--log('Actuele temperatuur: ' ..temp.. '°C')
windms = datatable.windms --windsnelheid in meter per seconde
--log('Windsnelheid: ' ..windms.. ' m/s')
RE: Wind speed close shutter - Erwin van der Zwart - 08.02.2020
Hi,
I would add a check to be sure that the values from the online service are received as expected, we do the same with a signal from a local weather station (alive signal).
Make a resident / scheduled script at like this:
Code:
lastupdate = grp.find('1/1/1').updatetime
difference = os.time() - lastupdate
if difference > then 3600 then -- 1 hour not changed
alert('No new value received from online weather service')
-- or mail / push / sms etcetera
endErwin