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How does data transfer work?
Posted: Thu 31 Mar 2011 3:19 am
by Krumlov
Hi Guys,
Things are going well but I have a question which relates how best to set up the system?
Essentially how does the data transfer work from the weather station to cumulus? Does Cumulus delete the history from the weather station as it reads it or does the weather station slowly fill up? If the weather station fills up should I delete the history or just let it overwrite the old? Does Cumulus get data from the weather station in real time or only at the 10min interval I set? If it is realtime what is the purpose of the 10 min interval?
If I have my laptop unplugged for a while does it download all the data from the weather station when it is plugged back in? What fidelity is lost, if any, if I don't leave the laptop plugged in all the time?
I also upload to Wunderground using rapid fire. Should I do this if the laptop is sometimes unplugged? When the laptop is plugged back in is all the stored data uploaded to Wunderground? Is there any real benefit to using rapid fire?
At the end of the day I want to be able to look back over a year and see accurate graphs of the data so am trying to understand how these data inter-relationships work.
Thanks for educating me!

Re: How does data transfer work?
Posted: Thu 31 Mar 2011 7:41 am
by steve
Krumlov wrote:Does Cumulus delete the history from the weather station as it reads it or does the weather station slowly fill up? If the weather station fills up should I delete the history or just let it overwrite the old?
Cumulus doesn't delete it; the memory fills up and then wraps around and the station reuses the 'oldest' locations, this is not a problem as long as you connect Cumulus often enough so that data that hasn't been downloaded yet doesn't get overwritten.
Does Cumulus get data from the weather station in real time or only at the 10min interval I set? If it is realtime what is the purpose of the 10 min interval?
The station updates every 48 seconds; Cumulus doesn't know when it's going to update, so it reads the data every 10 seconds and treats that as new data. Logging absolutely every set of data that's read doesn't have any real benefits, and would take up large amounts of disk space, so typically data will only be logged to disk every few minutes.
If I have my laptop unplugged for a while does it download all the data from the weather station when it is plugged back in?
Yes.
What fidelity is lost, if any, if I don't leave the laptop plugged in all the time?
The logger entries are 'snapshots'. Highs and lows between the snapshots don't get recorded, so will be lost.
I also upload to Wunderground using rapid fire. Should I do this if the laptop is sometimes unplugged?
It's up to you.
When the laptop is plugged back in is all the stored data uploaded to Wunderground?
In 1.9.1, yes.
Is there any real benefit to using rapid fire?
Benefit to whom? It depends on whether you want people looking at your WU site to be able to see your data updating at greater than your 'normal' WU update interval. Personally, I don't see the point.
Re: How does data transfer work?
Posted: Thu 31 Mar 2011 12:22 pm
by Krumlov
Thanks Steve,
I assume then the 10min interval I set is the logger interval for offline recording. Is that correct? Is the only downside to setting a shorter interval that the station would fill up faster?
I think I will turn rapid fire off then as I don't need historical data from every few minutes! I just noticed while turning that off that the WU has an update interval as well. Should that be set to 10mins the same as everything else or does it not matter? Would I be right in assuming that someone would set a lower interval if they wanted to capture fast changing events such as wind speed that would be lost when "offline" or inbetween WU updates?
As for 1.9.1 is that yet to be released or are people using a beta version? I have 1.9.0.
Thanks for the great app!

Re: How does data transfer work?
Posted: Thu 31 Mar 2011 12:40 pm
by steve
Krumlov wrote:I assume then the 10min interval I set is the logger interval for offline recording. Is that correct?
That's the interval that you set in the station yes; Cumulus has a separate interval for logging when it's running. It makes sense to have them both the same.
Is the only downside to setting a shorter interval that the station would fill up faster?
Yes, that's right.
I just noticed while turning that off that the WU has an update interval as well. Should that be set to 10mins the same as everything else or does it not matter?
It doesn't matter, but I guess it makes sense to use the same interval again.
Would I be right in assuming that someone would set a lower interval if they wanted to capture fast changing events such as wind speed that would be lost when "offline" or inbetween WU updates?
Yes, that's right.
As for 1.9.1 is that yet to be released or are people using a beta version?
It's still in beta, hopefully graduating to 'released' status quite soon.
Re: How does data transfer work?
Posted: Thu 31 Mar 2011 9:32 pm
by Krumlov
Ok Thanks very much Steve. I will wait for 1.9.1. Thanks again...

Re: How does data transfer work?
Posted: Thu 31 Mar 2011 9:38 pm
by sanramonrover
I thought I understood the EW and Cumulus system fairly well, but this has me stumped. Following on from Steve's
Cumulus doesn't delete it; the memory fills up and then wraps around and the station reuses the 'oldest' locations, this is not a problem as long as you connect Cumulus often enough so that data that hasn't been downloaded yet doesn't get overwritten.
My system doesn't update Cumulus with a full report. The console displays memory about 3/4 full, but Cumulus still doesn't show any past data. I just installed Cumulus 1.9 in my new computer, so there should be no issues with past records.
As well, Cumulus shows a MAX of -500 and a MIN of 999 Deg C. That is what it says
I am unable to clear the console memory due to the smashed touch screen, so have been relying on it refilling the memory with valid date. Perhaps that hasn't happened yet.
Its not practical to leave my PC running 24/7, so I fire it up, open Cumulus at least twice a day.
What difference should not having the transmitter hooked up? The TX is still in Costa Rica while the RX is in Canada. I expected Cumulus would simply record what the console shows, and put zeros for any data not supplied by the TX.
Re: How does data transfer work?
Posted: Thu 31 Mar 2011 9:47 pm
by steve
sanramonrover wrote:What difference should not having the transmitter hooked up? The TX is still in Costa Rica while the RX is in Canada. I expected Cumulus would simply record what the console shows, and put zeros for any data not supplied by the TX.
If the station is correctly reporting 'sensor contact lost', then Cumulus should just process the indoor data. If it's not reporting sensor contact lost, and is supplying an impossible value for one of the outdoor sensor readings, then Cumulus will be discarding all of the data (as discussed in the other thread).
If you look in the diags file, it should be clear what is happening.
Re: How does data transfer work?
Posted: Thu 31 Mar 2011 10:23 pm
by steve
steve wrote:If the station is correctly reporting 'sensor contact lost', then Cumulus should just process the indoor data.
Actually,
for logger data, it doesn't bother checking the 'sensor contact lost' flag, so any garbage outdoor values will cause the data to be discarded.
Re: How does data transfer work?
Posted: Fri 01 Apr 2011 12:41 am
by sanramonrover
I guess I don't understand enough. I appreciate your point Steve, and was just asking the forum in general for advice. Someone else must have had a similar problem?
[EDIT]
I looked into the diags folder, and here is the latest entry
http://www.griffco.ca/cr/weather/diags3-11.zip in zipped format.
[/EDIT]
Using a text editor, I can see where it says there are problems, but just don't know what to do about them.
Re: How does data transfer work?
Posted: Fri 01 Apr 2011 2:24 am
by PaulMy
Ok Thanks very much Steve. I will wait for 1.9.1. Thanks again...
I also was hesitant with installing the 1.9.1 beta but heard some good comment from users so eventually decided to install b.986 and am very glad I did. Looks great, works great as well and with several new features.
Paul
Re: How does data transfer work?
Posted: Fri 01 Apr 2011 7:17 am
by steve
sanramonrover wrote:I guess I don't understand enough. I looked into the diags folder, and here is the latest entry
http://www.griffco.ca/cr/weather/cumulus.004 Now I don't know what the extension should be, so can't even see it myself. [aarrgghh]
That URL gives me a 404. It's just a text file, you can view it in any decent text editor. It's probably best if you open a new thread, zip up the entire diags folder and attach it to a post. But bear in mind that I can't put a lot of effort into supporting broken or incomplete systems.
Re: How does data transfer work?
Posted: Fri 01 Apr 2011 5:18 pm
by sanramonrover
Previous post edited to show zipped diags folder.
Re: How does data transfer work?
Posted: Fri 01 Apr 2011 5:43 pm
by steve
It's giving stupid values in the logger data for outside temperature, so the data is being ignored:
3/31/2011 15:29:04.227 : EWUSB: Ignoring bad data: outtemp = -3276.69995117188
Also, when running live, you're allowing the computer to hibernate:
3/31/2011 16:00:00.824 : Writing todayfile, LastUpdateTime = 3/31/2011 4:00:00 PM raindaystart = 0
3/31/2011 16:01:46.501 : Error!!! Failed to write to USB!
3/31/2011 18:09:15.614 : Writing todayfile, LastUpdateTime = 3/31/2011 4:00:00 PM raindaystart = 0
31/03/2011 19:04:28.382 : Writing todayfile, LastUpdateTime = 31/03/2011 7:00:00 PM raindaystart = 0
31/03/2011 19:09:58.536 : Error!!! Failed to write to USB!
01/04/2011 09:04:56.503 : Error!!! Failed to write to USB!
01/04/2011 09:05:16.619 : Writing todayfile, LastUpdateTime = 31/03/2011 7:00:00 PM raindaystart = 0