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Adding solar sensor to Cumulus / Vantage Vue

Discussion specific to Davis weather stations
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BCJKiwi
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Adding solar sensor to Cumulus / Vantage Vue

Post by BCJKiwi »

Have searched but not found all that I would have liked.

Have a Vantage Vue which does not have the ability to add extra sensors directly.

After some research I have come to the following conclusions.
The Davis way
1. replace VV with VP2 (or the ISS off VP2) and add solar - at significant expense
2. add an Envoy plus solar - also at significant expense
'3rd party'
3. add a Hobby board '1 wire' and use a picaxe (a simple to use microprocessor with 1 wire support built in - http://www.picaxe.com/) or similar to read the one wire sensor data and send the text file in B/L format to Cumulus via serial/USB.

So, before proceeding any further I am seeking some clarification/confirmation.

a. are options 1 and 2 the only ones for doing it the 'Davis way' or have I missed something?
Just found the Davis 6450 can be purchased for around US$144 from Archer and others. This appears to be a self contained unit that produces a 0-2.5V output so would be usable in the same manner as the Hobby-Board sensor - i.e. with a picaxe interpreting and outputting a B/L data file to Cumulus.
b. If I go with option 3 (or any practical aternative that anyone may suggest), will Cumulus be able to incorprate this data into;
- the PC display
- the website data.

Does Cumulus do all the calculations discussed in various pages on this forum in place of the calculations that would have been done by the Davis console - i.e. all the daylight stuff plus EVT?

c. is there a more suitable sensor than the Hobby Board sensor?

Thanks
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steve
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Re: Adding solar sensor to Cumulus / Vantage Vue

Post by steve »

BCJKiwi wrote:Does Cumulus do all the calculations discussed in various pages on this forum in place of the calculations that would have been done by the Davis console - i.e. all the daylight stuff plus EVT?
What sensors are you proposing to add?

If EVT is evapotranspiration, then no, Cumulus doesn't calculate that. I'm not sure what the "daylight stuff" that would have been done by the Davis console is?

If you get data into Cumulus using a file in the Blake-Larsen/Cumulus format, then you have to supply sunshine hours so far today and whether it's currently sunny or not, and those are the only two values that Cumulus uses from that file.
Steve
BCJKiwi
Posts: 1255
Joined: Mon 09 Jul 2012 8:40 pm
Weather Station: Davis VP2 Cabled
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Re: Adding solar sensor to Cumulus / Vantage Vue

Post by BCJKiwi »

steve wrote:
BCJKiwi wrote:Does Cumulus do all the calculations discussed in various pages on this forum in place of the calculations that would have been done by the Davis console - i.e. all the daylight stuff plus EVT?
What sensors are you proposing to add?

If EVT is evapotranspiration, then no, Cumulus doesn't calculate that. I'm not sure what the "daylight stuff" that would have been done by the Davis console is?

If you get data into Cumulus using a file in the Blake-Larsen/Cumulus format, then you have to supply sunshine hours so far today and whether it's currently sunny or not, and those are the only two values that Cumulus uses from that file.
I thought I had covered the sensor options.
Basically the Full Davis approach is more than I want to spend at this time.
So that leaves either a Hobby-Boards '1 wire Solar Radiation Detector' or the Davis 6450.
In either case I would connect that to a PicAxe Microprocessor which would then send the B/L file with sunshine hours and issunny to the PC so Cumulus can read it as you suggested to someone else in a thread I can no longer find.

In another thread which I also cannot find right now, you discussed at some length the calculation methods for ET and I understood from that thread that Cumulus would calculate the ET as the Davis console did not do a good job of it (or it was not coming through the DLL properly).
Since all the other sensors via Davis or FO provide either Lux or w/m2 I had assumed that all this would have been covered already within Cumulus somewhere. I assume the reason this has not been covered in the B/L file is that those with a B/L would be using the software supplied with the unit.

However, if you do have w/m2 input being handled in Cumulus and displayed on the graphs etc, is there any reason why that figure could not be supplied in a B/L type file and used in the same way it is if the sunshine data were received from a Davis console?

If I get a little more time I'll try to find the threads refer to above and give you the references.
Thanks
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steve
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Re: Adding solar sensor to Cumulus / Vantage Vue

Post by steve »

Cumulus doesn't currently calculate ET. It may do one day, but my recollection is that the calculation is very complex; there would also be a lot of extra code to manage the daily totals etc, as with rainfall.

The B/L file could be used to supply the solar radiation value, yes (it may do already, I can't remember), and yes, at some point I might get around to doing some changes to Cumulus which would allow it to use that value instead of the value supplied by the weather station in the normal way.
Steve
BCJKiwi
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Joined: Mon 09 Jul 2012 8:40 pm
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Re: Adding solar sensor to Cumulus / Vantage Vue

Post by BCJKiwi »

Hi Steve,
Am still working on adding Solar to my system.
As the information I can submit to Cumulus via the B/L SRsunshine.dat file method is so limited, I am considering the option of directly manipulating the various log files.

I have determined from the Wiki that the webtags are created from the various log files at the time of sending. (Edit - not in wiki , not sure where I got this info but is not correct - see Steves explanation below - BCJKiwi) However I am unable to determine the sequence for the creation of the log files / realtime file.

As each of these files contain different fields/data there does not seem to be a 'key' file from which the others are derived. This would suggest there is no one point where the changes could be made.

What I have not been able to establish is the sequence that Cumulus follows in creating/reading the various files. without this it seems I could waste a lot of time and effort for no return.

I presume that any changes of this nature will likely not appear in the graphs but I would like this data to be stored in Cumulus along with everything else rather than being a completely separate data file. The preference is to create a set of data files that would be the same as if I had a VP2 with solar.

Also, what happens to the dayfile over time - does it just keep growing forever or is a new one created each year?

Thanks
Last edited by BCJKiwi on Sat 15 Dec 2012 8:19 pm, edited 1 time in total.
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steve
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Re: Adding solar sensor to Cumulus / Vantage Vue

Post by steve »

BCJKiwi wrote:I have determined from the Wiki that the webtags are created from the various log files at the time of sending.
They're actually created from data stored in memory, not from the log files. If it says in the wiki explicitly that the web tag values are read from the log files, then it needs to be changed.
However I am unable to determine the sequence for the creation of the log files / realtime file.
Cumulus runs a timer which fires once a minute, when the clock minute changes; it performs various actions at this point. If the current minute on the clock is a multiple of the log interval, it writes to the log file. Realtime.txt creating is done based on completely separate timer which fires at the configured interval. The data written to the realtime.txt file is taken from data stored in memory, as with the web tags.
Also, what happens to the dayfile over time - does it just keep growing forever or is a new one created each year?
There's only one file.
Steve
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