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VP2 Rainfall

Discussion specific to Davis weather stations
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eddyr
Posts: 6
Joined: Tue 02 Jun 2009 4:13 pm
Weather Station: Vantage Pro2

VP2 Rainfall

Post by eddyr »

Hi,

I'm new to all this so please bear with me.
I have a VP2 and have installed the 0.2mm rain gauge weight. Yesterday & today are the first rain we have had for me to test this. The VP console says 0.2mm yesterday & 0.4mm today but Cumulus says 0.3mm & 0.5mm.

So my question is, how can I get 0.3 & 0.5 when the multiplier, as I understand it, is 0.2, that is each tip of the rain collector = 0.2mm?

I have checked the Cumulus multiplier settings and rain is set to 1.

Is there anything I can set to correct this?

On another matter, is there a 'wishlist' type of forum?


Thanks Eddie
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steve
Cumulus Author
Posts: 26702
Joined: Mon 02 Jun 2008 6:49 pm
Weather Station: None
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Location: Vienne, France
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Re: VP2 Rainfall

Post by steve »

eddyr wrote:I have a VP2 and have installed the 0.2mm rain gauge weight. Yesterday & today are the first rain we have had for me to test this. The VP console says 0.2mm yesterday & 0.4mm today but Cumulus says 0.3mm & 0.5mm.
Have you definitely set the rain collector to 0.2mm correctly on the console? The Davis DLL that Cumulus uses has an initialisation function which Cumulus calls at startup which reads the setting from the console, and then converts the readings to actual amounts when Cumulus reads the data.
On another matter, is there a 'wishlist' type of forum?
There's no specific area for them, they just get posted with everything else. I don't propose to do any majir changes to version 1 now, but I'm happy to take suggestions for v2. Of course, when I actually get to the position of being able to do something about them, I'll probably have forgotten. But it's still worth posting now as it may help shape the way I'm going with v2.
Steve
eddyr
Posts: 6
Joined: Tue 02 Jun 2009 4:13 pm
Weather Station: Vantage Pro2

Re: VP2 Rainfall

Post by eddyr »

I sould explain.
The VP2 is connected to the PC via Davis Envoy & the VP Console is downstairs.

I have checked the console and that is set to 0.2mm. I have checked the station config in Weatherlink and it shows this set to 0.2mm.

However, what I had not done, before 2 minutes ago, is set the Rain Calibration in the Setup menu in Weatherlink. I had made an assupmtion that if it was set in the station config then that was ok. Perhaps that assumption was wrong?

Eddie
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steve
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Posts: 26702
Joined: Mon 02 Jun 2008 6:49 pm
Weather Station: None
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Location: Vienne, France
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Re: VP2 Rainfall

Post by steve »

I wouldn't have thought you needed to do anything in Weatherlink that would affect Cumulus. But I don't know anything about the Envoy, so maybe that needs the rain collector type configuring also, and maybe you have to use WL to do that?

There's a function in the DLL which allows you to set the rain collector type in the DLL, rather than telling the DLL to set itself to the same value as the console, which normally works. Perhaps for the Envoy case I need to provide an option to use this function.
Steve
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steve
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Joined: Mon 02 Jun 2008 6:49 pm
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Re: VP2 Rainfall

Post by steve »

Having had a quick look at the manual for the Envoy, I've realised that you have to use WL to set those up anyway, as basically they are consoles without a display. So I think that the part you were missing is what you have now done, to set the rain collector type in the Envoy using WL, just as you would do with an ordinary console using the console itself.
Steve
eddyr
Posts: 6
Joined: Tue 02 Jun 2009 4:13 pm
Weather Station: Vantage Pro2

Re: VP2 Rainfall

Post by eddyr »

Sorry, crossposted there.

I think you are correct. I added the Envoy after the console and think I should have redone the configuration via the WL setup menu once the Envoy was connected to the PC.

It is however confusing that you are given an option of altering that particular setting via the setup menus and via the staion config screen. When I saw the rain set to 0.2mm in the station config screen I naturally assumed that the Envoy had been set to that.

To clarify things:
I set up the console correctly and that seems to display in multiples of 0.2mm of rain.
Also note that WL is also recording in multiples of 0.2mm
I then added the Envoy. This does not come with software or anything and the station setup is only interested in what VP etc you have.
Since adding the Envoy I have not altered any settings in WL.
So this still begs the question of why the Console, Weatherlink & Cumulus differ.

I'll keep an eye on it next time it rains, which won't be long, and see if the levels increase in 0.2mm steps since I have made the alterations in WL.
eddyr
Posts: 6
Joined: Tue 02 Jun 2009 4:13 pm
Weather Station: Vantage Pro2

Re: VP2 Rainfall

Post by eddyr »

OK,

Had some more rain overnight and Cumlulus now seems to be logging in 0.2mm steps.

I have, I hope, attached a pdf of the total rain graph for yesterday and, as the rain must have been slow, you can clearly see the steps that were logged. You can also clearly see that only one is a 0.3mm step and the rest are 0.2 as they should be.

This seems a bit strange as you would have thought it would be one or the other. I would assume the signals from the rain collector are processed in the console or the envoy as the console would still work if you didn't have WL. I would further assume that the envoy is a console without the screen etc.

So surely it should be a simple digital thing - the reed switch changes state each time the rain bucket tips and each change of state = 0.2mm rain. So why you would get 1 tip = 0.3mm is confusing.

Another point is, why would the toal rainfall in the graph fall back from a peak of 0.7mm to 0.5mm? The logs are set to roll over at midnight so shouldn't this parameter keep rising or at least stay at a high point until then?

Eddie
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steve
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Re: VP2 Rainfall

Post by steve »

eddyr wrote:So surely it should be a simple digital thing - the reed switch changes state each time the rain bucket tips and each change of state = 0.2mm rain. So why you would get 1 tip = 0.3mm is confusing.
The Davis DLL that Cumulus uses converts tips into measurements, using the rain collector setting in the console (or the Envoy, in this case).
Another point is, why would the toal rainfall in the graph fall back from a peak of 0.7mm to 0.5mm? The logs are set to roll over at midnight so shouldn't this parameter keep rising or at least stay at a high point until then?
It should. I can only think that the DLL and/or Envoy started reporting a lower total for some reason.
Steve
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