Author Topic: Sensing & displaying first sign of rainfall?  (Read 387 times)

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Offline GlynH

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Sensing & displaying first sign of rainfall?
« on: June 27, 2021, 11:50:13 AM »
Wasn't sure whether to post here or in the Hydreon RG-11 forum but as I already have the VP2 and I mention other sensors I'll take a chance and post here!

I have always wanted a way of knowing when it starts and stops to rain rather than wait for enough rain to make the bucket tip and register and I stumbled across the Hydreon RG-11 which seemed like an answer to my prayers.

I have taken onboard the accuracy issues when it comes to measuring rainfall but I would only use it for early rainfall detection as the VP2 would be my primary rain measurement device.

So I was thinking...would it be possible to use the Hydreon for this particular purpose and if so would it be possible to connect it into the Davis 6332 that I intend to use for a remote anemometer or is that just wishful thinking on my part?

Is it even possible to connect it to the Davis setup in any way or would I have to cobble together its own interface?

Of course even if I could connect there might be nothing I could do log/display the data in this scenario anyway...

Failing all that is there any other device that might do what I am looking for?

I got excited when I saw the 6420 Davis Leaf Wetness Sensor but that needs its own 6345 Leaf & Soil Moisture Station so probably not the cheapest solution although it could be the best and would at least play nice with my existing Davis setup.

If the Leaf Wetness Sensor were suitable for my intended purpose where/how is the logged data displayed on weatherlink.com or in the app?

Failing all that would either sensor or some other solution work with the WLL with the same caveat about being able to do something & display the data anyway?

Thanks & kind regards,
-=Glyn=
« Last Edit: June 27, 2021, 03:17:21 PM by GlynH »

Offline doubleohwhatever

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Re: Sensing & displaying first sign of rainfall?
« Reply #1 on: June 27, 2021, 02:09:11 PM »
I've never had the need to use or even play with a leaf wetness sensor. However, I have three concerns that may or not be problems for your intended use:

1) The update interval for leaf wetness sensors is rather slow.
2) Would fog/frost result in false start events?
3) Would moisture have to evaporate for an event to "end"?

Hopefully someone who is more familiar with the Davis leaf wetness sensor will chime in on the suitability of using that sensor for your purpose.

If I were given the task of adding rain start/stop indicator via a RG-11/9 to a Davis system, I would probably go with a RG-11 as it has both a heater to reduce frost issues and it has their "Itís Raining Mode" feature. I would interface it with the wind port on the ISS board as the wind values are updated the quickest. You could likely even have it report several different values based on conditions. Ex:

0 MPH = Not raining
10 MPH = Drizzle
........
50 MPH = Raining cats, dogs, and whale sharks

The obvious caveat here is that on weatherlink.com it would just show up as a anemometer. You would just have to know what the values mean.

Anyway, that's just off the top of my head. I'm 100% sure something like what I described above is possible. However, I'm not sure it would be worth the hassle. That's for you to decide though. If you do decide to go down this road, an arduino and this page will get you started:
https://www.wxforum.net/wxtech/Anemometer-Vane.htm

Offline GlynH

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Re: Sensing & displaying first sign of rainfall?
« Reply #2 on: June 27, 2021, 03:27:35 PM »
Thanks for taking the time to reply.

InterestingÖsome things I never even thought of!

Itís good that itís possible to interface it to the wind port as when I move the anemometer to the chimney that port will be the only one free on the ISS.

Not so good that it would show up as an anemometer on WeatherLink though although Iím wondering whether I might choose not to display but hoping it would be possible to set up an Alert to notify me when it senses rain as that would be my minimum requirement.

Hopefully others who have been down this road before might pop in and shed some more light.

Thanks & kind regards,
-=Glyn=-

Online johnd

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Re: Sensing & displaying first sign of rainfall?
« Reply #3 on: June 27, 2021, 04:17:28 PM »
We've been around this sort of loop multiple times in the past I think, with various ideas and sensors and the answer is usually the same - very interesting idea but difficult to do cost-effectively. In part it depends what receiver and data handling you're using, ie:

If you just have a standard Vue/VP2 console/receiver and no supplementary transmitter, then your choice of inputs is poor. If you don't have solar/UV sensors then you could potentially use those, but as analogue 3v inputs you would need some circuitry in between;

Adding a 6332 transmitter to a standard console set-up doesn't help much because the console can only receive from a single anemometer or rain gauge and the other inputs (T/H etc) have other issues. Adding a 6345 transmitter opens up more possibilities but as you say just adding a single sensor to a 6345 is a relatively costly option.

Things are a bit brighter if you have a Weatherlink Live unit, which obviously can receive multiple anemometers, rain gauges etc. So adding a 6332 transmitter would be more of a possibility. There are still some challenges in how you would interface eg an RG series sensor but WLL does offer more scope for development. Remember that Instromet do a sunshine hours sensor that can interface to the rain gauge input of a Davis station. (36 secs of bright sunshine = 0.01" rain IIRC). so the principle is established but presenting the data at the far end isn't so neat.
Prodata Weather Systems
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Offline dendrite

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Re: Sensing & displaying first sign of rainfall?
« Reply #4 on: June 27, 2021, 06:41:37 PM »
I've been using a leaf wetness sensor for precip detection for over a decade now. I use a 25W light bulb inside of a metal electrical box and mount the leaf wetness sensor to that so it always stays dry except during times of rain. When it's showery it usually reads 1-14 and in steady precip it's a flat 15. With snowfall it's a little different. I've had steady snowfall with values around 5.

Offline vreihen

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Re: Sensing & displaying first sign of rainfall?
« Reply #5 on: June 27, 2021, 07:55:23 PM »
This very thing is the one thing that Weatherflow's haptic rain sensor in their Sky and Tempest PWS packages excels at.  It won't integrate into the Davis ecosystem, but it will send rain start alerts to your smart phone running their app.  The common use is for closing windows and stuff in home automation systems when the first drops of rain are detected.....
WU Gold Stars for everyone! :lol:

Offline GlynH

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Re: Sensing & displaying first sign of rainfall?
« Reply #6 on: June 28, 2021, 06:44:55 AM »
Well I did search for Leaf Wetness Sensor but drew a blank... :?

Judging from the replies it is not as straightforward as I had hoped but it can be done with the caveats;

1. Davis 6420/6345 - integrated but expensive
2. Davis WeatherLink Live & 6332 - also expensive and still requires interface solution for Hydreon RG-11
3. Weatherflow Haptic Rain Sensor - standalone/no integration/separate app

I was really hoping the simple (read cheap) solution would have been to use the Hydreon RG-11 ideally connected to one of the four spare inputs in the additional 6332 I have for the remote anemometer as it's a real pity to let those additional inputs go to waste but it seems at the moment the best option for me would be the Davis 6420/6345?

So assuming I go 6420/6345 how would I add/incorporate these into my existing Davis account and how would this device and its data then be displayed on Weatherlink.com website and the mobile app for example?

And can I choose to include/exclude specific data from being displayed as I can with my existing Davis VP2 and Airlink and could I then utilise the Alarm to notify me of rain start/stop events for example or is all of this wishful thinking?

Thanks & kind regards,
-=Glyn=-

Online johnd

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Re: Sensing & displaying first sign of rainfall?
« Reply #7 on: June 28, 2021, 07:39:55 AM »
Glyn: I don't recall exactly what sort of system you have, but it sounds like a standard VP2 with console and logger (ie no WLL)?

Assuming so, then yes, 6345/6420 is probably the most straightforward way to go because this will integrate easily into your existing set-up and the leaf wetness will be logged and uploaded by standard data handling. If we're talking about uploads to weatherlink.com then you can choose which parameters you want displayed in the browser app Bulletin, but the phone app is largely a fixed format presentation.

Perhaps worth adding that the 6345 has an input for a second leaf wetness sensor and I guess this could in principle be used for an RG series sensor. You could potentially compare readings from the two side by side and get some sense of their relative sensitivity. I don't know for sure but suspect that the 6420 is read every minute or so by an AC signal from the SIM board (but, that said, it could also be a simple DC voltage), which effectively measures the sensor's resistance. So potentially you might be able to do the same with eg an RG11 sensor on the second input, probably with a resistor in the line - the exact circuit might need a little thought but should be fairly simple if you were just dealing with an on/off response rather than looking for something more graduated.
Prodata Weather Systems
Prodata's dedicated Davis EnviroMonitor website
UK Davis Premier Dealer - All Davis stations, accessories and spares
Littleport, Ely, Cambs UK

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Offline miraculon

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Re: Sensing & displaying first sign of rainfall?
« Reply #8 on: June 28, 2021, 09:10:18 AM »
I use an RG11 in 0.001"/tip emulation mode connected to my T/H station. The Hydreon is wired to the RAIN port. I decided on 0.001" per tip as a compromise for relay life as opposed to a more sensitive setting.

See https://www.wxforum.net/index.php?topic=25199.msg261931#msg261931

Also, you can view the data from this Hydreon at http://www.rogerscityweather.com/wxISS-Rain.php at the bottom of the page. I use this to note start/stop times on CoCoRaHS with an appropriate comment. I have been doing this for several years now.

Greg H.


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CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
Amateur Radio Callsign: KE8DAF

Online johnd

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Re: Sensing & displaying first sign of rainfall?
« Reply #9 on: June 28, 2021, 09:39:50 AM »
@miraculon: But you are using an Envoy8X AIUI, which makes this possible. (The 8X being in a sense the forerunner of the current WLL but without the wl.com uploads; and with the 8X no longer being made though I guess one or two are still lingering in the supply chain.)
Prodata Weather Systems
Prodata's dedicated Davis EnviroMonitor website
UK Davis Premier Dealer - All Davis stations, accessories and spares
Littleport, Ely, Cambs UK

Sorry, but I can't help with individual issues by email. Please post your issue in the relevant forum section here & I will comment there if I have anything useful to add.

Offline miraculon

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Re: Sensing & displaying first sign of rainfall?
« Reply #10 on: June 28, 2021, 11:07:53 AM »
@miraculon: But you are using an Envoy8X AIUI, which makes this possible. (The 8X being in a sense the forerunner of the current WLL but without the wl.com uploads; and with the 8X no longer being made though I guess one or two are still lingering in the supply chain.)

True, I suppose a WLL would be required then...
Thanks for clarifying this.

Greg H.


Blitzortung Stations #706 and #1682
CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
Amateur Radio Callsign: KE8DAF

 

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