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Latest Cumulus MX release v3.0.0 build 3050 - 1 May 2019.
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Offset in the daily rain value

Discussion of version 3 of Cumulus, which runs on Windows, Linux, and OS X. All Cumulus MX queries in here, please.

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Hyrules
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Offset in the daily rain value

Post by Hyrules » Wed 01 May 2019 11:10 pm

Hi

For a few days now (at least since Ive noticed it) I have been having a small offset in the daily rain and rain rate. I use a davis vantage pro 2. For example i have a 2.3mm daily rain on the console but cumulus mx 3049 gives me a 1.8mm rainfall. Same goes for the rain rate. at the moment I have 2.5mm/hr but cumulus mx gives me 2.0. The multiplier is at 1 at the moment. I dont know if it should be anything else. Any help would be appreciated.

Thanks
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freddie
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Re: Offset in the daily rain value

Post by freddie » Thu 02 May 2019 7:44 am

It looks to me as if there is a difference in rain tip values between what is configured for your Davis station and what you have configured in Cumulus. It appears that you have your Davis configured at 0.01 inches (or 0.25mm), and that Cumulus is configured at 0.2 mm. Both the station and Cumulus count bucket tips to measure rainfall, as the amount of rainfall required to tip the buckets is a known quantity. You should confirm this by using the Davis console (or possibly WeatherLink) to check your tip value; and check in Cumulus.ini for the value entered against DavisRainCollectorModel. There are some notes in the Wiki that show you which value to use in Cumulus depending on what your Davis is set to - see the relevant section of the Wiki.
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Hyrules
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Location: Gatineau, Quebec, Canada

Re: Offset in the daily rain value

Post by Hyrules » Thu 02 May 2019 7:52 pm

I have checked the console and its indeed at 0.01in. Same goes for Weatherlink. I have added the relevant key to the ini but is it supposed to change the value already recorded or do I have to wait for the next rain to see if this fixes it ? thanks for your help by the way.
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freddie
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Re: Offset in the daily rain value

Post by freddie » Thu 02 May 2019 8:11 pm

Did you edit the ini with cumulus stopped? Also, it won't affect rain already recorded - you will need to go through your data files (with cumulus stopped) and adjust the values manually, unfortunately.
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Hyrules
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Location: Gatineau, Quebec, Canada

Re: Offset in the daily rain value

Post by Hyrules » Thu 02 May 2019 10:18 pm

yes I modified the ini while cumulus was not running. No i didnt modify the actual rain. Its not that important at this point and I dont know since when its like that so I will just live with it. I will wait for the next rain to see if this is fixed thanks.
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Hyrules
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Re: Offset in the daily rain value

Post by Hyrules » Fri 03 May 2019 11:16 am

Well it's raining this morning and it's didn't fix the issue. There must be something else. I have rechecked the cumulus.ini and the DavisRainCollectorModel=1 is still there but I'm not sure
it's working as intended or at all.
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freddie
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Re: Offset in the daily rain value

Post by freddie » Fri 03 May 2019 11:35 am

Hyrules wrote:
Fri 03 May 2019 11:16 am
I'm not sure it's working as intended or at all.
If that were genuinely the case then I think there would be a few more posts about what you are experiencing. Having said that, it should be easy enough to check in the code. I expect the current maintainers of the code will read this post at some point.
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Hyrules
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Re: Offset in the daily rain value

Post by Hyrules » Fri 03 May 2019 12:06 pm

Most likely indeed. I'm a c# programmer myself. I'll try to find the section of the code to see if there is anything I can help with or if it's me :D
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mcrossley
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Re: Offset in the daily rain value

Post by mcrossley » Fri 03 May 2019 12:08 pm

Is the rain increasing at the same rate on the console and Cumulus, ie is there just an offset now rather than a difference in rate in increase? If so is the console date/time set correctly?

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Hyrules
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Re: Offset in the daily rain value

Post by Hyrules » Fri 03 May 2019 12:16 pm

Hi Mark,

There is an offset as well in the rain rate and yes the date / time is correct on the console.

Rate show at 1mm at the moment on Weatherlink and 0.8mm on Cumulus.
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Re: Offset in the daily rain value

Post by mcrossley » Fri 03 May 2019 12:26 pm

Sorry I didn't mean the rain rate, but the rate of increase in the rainfall total.

What is your met day set to? Probably best to zip up your diags folder and post it

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Hyrules
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Re: Offset in the daily rain value

Post by Hyrules » Fri 03 May 2019 12:39 pm

Argh god I think you got it. the RainDayThreshold is set to -1 which is 0.2mm and should probably be at 0 for 0.01in. I have added the log just in case.
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Re: Offset in the daily rain value

Post by mcrossley » Fri 03 May 2019 1:21 pm

The rain threshold is OK at -1, it means it will use 0.01 inches now.
I do notice that your Cumulus and console logging intervals do not match (1 minute and 5 minutes respectively), so you have very slow start-ups where the entire logger contents has to be downloaded.

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Hyrules
Posts: 21
Joined: Sun 03 Jan 2010 4:55 am
Weather Station: Davis Vantage Pro 2
Operating System: Win 7 x64
Location: Gatineau, Quebec, Canada

Re: Offset in the daily rain value

Post by Hyrules » Fri 03 May 2019 2:23 pm

I have changed the logging interval to 5 minutes in cumulus. I don't know if this will fix it but i'll see what happens.
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Hyrules
Posts: 21
Joined: Sun 03 Jan 2010 4:55 am
Weather Station: Davis Vantage Pro 2
Operating System: Win 7 x64
Location: Gatineau, Quebec, Canada

Re: Offset in the daily rain value

Post by Hyrules » Fri 10 May 2019 12:10 am

still no joy. There is still an offset in the current daily rain total. rain is a 0.9mm should be 1.0mm and rate is at 1.0mm should be at 1.3mm. I have take a clean version of cumulus mx and recreated the config and ini and files and the offset is still there.

Is this still valid : https://cumuluswiki.wxforum.net/a/Cumulus_MX about the raingauge for davis owner note ?

VPrainGaugeType=1

after adding this line the rate is now good. I have adjusted the rain manually. Let's see what happens.
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