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RainMachine and Davis Weather Stations

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20 comments

  • Avatar
    lanbrown

    Please see this thread on this very topic:

    https://support.rainmachine.com/hc/en-us/community/posts/360012369793-Get-weather-data-from-Davis-Weatherlink 

  • Avatar
    noopara

    Thanks for the reply.  I have seen that post and others wanting support of Davis Weather Stations without the WeatherUnderground feed.  What I would like to see RainMachine programmers do is provide support for a direct connection through a local network to the Davis IP Logger.  Davis'  Serial Protocol document which was published over 5 years ago provides the protocol for both a serial/USB connection as well as an IP connection.  There are programmers on GitHub that have done this and made their code available to others which would give RainMachine a jump start on developing the necessary code to make their claim that they support Davis Weather Stations a reality.  Here is a link with the code for reading the Davis data: https://github.com/mkeymolen/DavisVantage.WeatherReader

    RainMachine has responded to me and said the Davis is an acceptable weather source.  I imagine that applied when WeatherUnderground was still a viable option for an Internet source.  It probably still is with OWM.

    RainMachine needs a solution that would allow direct transfer of data from local weather stations.  This is not only more reliable from a connectivity stand point (IP or serial vs Internet) but provides more accurate local data.  For those of us that operate large automatic Et based irrigation systems, accurate LOCAL weather data is critical.  Forecast data should come from the Internet and using a current data from a local weather station with a direct connection is the most reliable approach.

    The difficulty is that there are many weather stations manufacturers and no standard for data delivery.  RM would have to acquire one of each weather station to do this and they probably have a very small staff of programmers to develop the code.  It's probably not possible given all the other priorities.  If RM could at least develop and integrate an XML and csv parser into their product then a product such as Cumulus or WeatherDisplay and others could provide the XML or csv file.  This is a workable compromise in my opinion.

     

     

  • Avatar
    lanbrown

    Your statement of "The difficulty is that there are many weather stations manufacturers and no standard for data delivery." says it all.  Even within the Davis product family, there is more than method.  The serial/USB would pretty much be a no go.  Many people their controller is either outside or in the garage; that probably is not where they have their control unit for their PWS.  Can you extend the serial or OSB connection?  It is possible but people may not be able to get wiring in place to accomplish that.  Without a standard in terms of the data, there is just no way that RM could support everything.  Add in the cost of some of the PWS units, their complexity, size, etc. and may people won't buy them.  So you already have a smaller market and then you need to figure out how many of that small market would buy a RM.

    The best that RM can do, allow you to send a csv file or some other format for the RM to process.  Getting that file would be up to the user.  The RM platform is pretty open, so it can be done.

  • Avatar
    noopara

    I have a Davis Envoy that I have used for many years to connect via a Davis USB/Serial Logger connected to a small computer running Cumulus.  Cumulus generates a csv file which I have used to feed weather data to another program that controls my sprinklers.  It all works great, but when I sell my house it's probably going to be a problem for the new owner unless he has a technical background and the desire to mess with it...not likely.  So I am looking for a solution to take it's place down the road.  RM is a good candidate since it has a control panel that can be used like a conventional timer controller.  Like you, I think that if RM could build a software module that would read current weather data from a csv or XML file that they would find an increased demand from users like myself.  

  • Avatar
    GHammer

    There is a extension for weewx that was written by RainMachine developers that will push your local data to your RM.
    Of course, you have to have weewx up and running, but if you have a weather station, why not?
    Then you currently need to be on the beta RM release.

    I've been running this for a couple of weeks and it works well.

    https://github.com/weewx/weewx/wiki/RainMachine 

  • Avatar
    noopara

    Excellent.  That would be very useful for some users. 

    I'm helping RM with a new project so they can write the code to connect directly to a Davis IP Data Logger and download weather data from my weather station directly into RM.  I would rather not have to rely on some other program like WeeWx or the Internet for local weather.  When they get this working, I'll be getting line to buy a couple of their boxes for my 22 zone sprinkler system.

  • Avatar
    GHammer

    I think an 'open' solution is going to be the better way.
    weewx, for example, has connectivity to many type of PWS and its hardware needs are puny.

  • Avatar
    noopara

    I would agree with that if there was hardware for the WeeWx to run on.  In my case, it's only the weather station and the RM.  Then there's reliability.  Less hardware and software is usually more reliable in the long term.

  • Avatar
    GHammer

    Less of anything is always good in my experience.

    A counter to that is how many people already have a weather station that is not a Davis that can take advantage of a 'universal' method of getting their weather data into their RM.

    Except for running a little Pi or other Linux box, there's no overhead. Mine sits in the basement quietly doing its thing. I do run a website with my weather data but that is also a no maintenance thing and not needed for the RainMachine connection.

    Anyway, as I said, here's an option that exists and works on nearly any PWS I can think of.

  • Avatar
    noopara

    Where I'm headed is to simplify my complicated JDS Stargate and HomeSeer driven home automation system that consists of several Winx and Linux computers bit by bit so that when I sell the home I can leave it with something that the new owner can cope with.  Having the independently controlled 22 zone sprinkler system run with a control panel for manual control and automatic control using local weather data independent of the Internet is just the ticket.  

    RM is working on the code now which will allow a RM to Davis weather stations directly.  

     

  • Avatar
    Patrick Trivett

    I'm very curious to see the solution as well, as this too is my very problem.

     

     

  • Avatar
    Nicholas

    Thanks to Noopara we now have a alpha version of a parser for Davis WeatherLinkIP module here

    For Davis there is also a WiFiLogger Parser and WeatherLink API service Parser.

  • Avatar
    Patrick Trivett

    I was just thinking about this last night again. I really do appreciate your efforts here, as well as the fact that you've bypassed the cloud necessity of the offsite upload and return loop, as well as required the paid account access demanded by Davis just to provide this simple data which is available on the LAN. Although I like WeeWX and REST-API, too many Raspberry Pis with unique one-off  apps & scripts to link simple data do not provide the suitability to the average-Joe user/consumer. 

    I'm excited to begin to integrate my onsite data into the algorithm! 

  • Avatar
    Patrick Trivett

    Nicholas - 

    Any particular reason that this parser indicates that the data its providing the rain machine is "weather forecast" (blue dot in WebUI), rather than "weather station" ? Does this make any type of difference per se?

     

  • Avatar
    Nicholas

    No difference, it's an overlook.

  • Avatar
    noopara

    Thanks to Nicholas, Nicu and everyone else that had a hand in this.  This is great news.  I will be testing it with an HD 16 very soon.

  • Avatar
    Patrick Trivett

    Thanks for Noopara and Nicholas for your efforts. I integrated it seamlessly last night, and it works like a charm on my HD-12. 

     

    - Patrick T.

  • Avatar
    noopara (Edited )

    I've got it working now.


    Here's the data from the log:

    2018-11-21 08:06:50,612 - INFO  - user-weatherlinkip-parser.py:55 - Sent LOOP command
    2018-11-21 08:06:55,620 - INFO  - user-weatherlinkip-parser.py:66 - Recv timeout (timed out) retrying.
    2018-11-21 08:06:57,626 - INFO  - user-weatherlinkip-parser.py:69 - Sent LOOP command
    2018-11-21 08:06:57,991 - INFO  - user-weatherlinkip-parser.py:77 - Parsing Response
    2018-11-21 08:06:57,993 - INFO  - user-weatherlinkip-parser.py:118 - Barometer: 98.194
    2018-11-21 08:06:57,995 - INFO  - user-weatherlinkip-parser.py:123 - Outside Temp: 6.66666666667
    2018-11-21 08:06:57,997 - INFO  - user-weatherlinkip-parser.py:130 - Wind Speed (10min avg): 0.0
    2018-11-21 08:06:58,014 - INFO  - user-weatherlinkip-parser.py:133 - Humidity: 93
    2018-11-21 08:06:58,016 - INFO  - user-weatherlinkip-parser.py:139 - Solar Radiation: 7
    2018-11-21 08:06:58,018 - INFO  - user-weatherlinkip-parser.py:144 - Day Rain: 0.254
    2018-11-21 08:06:58,020 - INFO  - user-weatherlinkip-parser.py:150 - Day EvapoTranspiration: 0.0
    2018-11-21 08:06:58,022 - INFO  - user-weatherlinkip-parser.py:157 - Condition: 3 -> 18
    
    
    

    The weather station console shows the following:
    Barometer = 29.69 (not same as parser, parser reported 98.194)
    Humidity = 93 (same as parser)
    Temp = 44 F (parser reported 6.111 which is close to what it would be in Celsius.  It should be 6.666)
    Wind = 0 (same as parser)
    Day Rain = .01 (parser reported .254 which must be in mm)
    Solar = 7 (same as parser)
    ET = 0 (same as parser)

    Seems that the parser is not using the set units from the settings table and perhaps there is a problem with the F to C conversion factor??

    The Barometric pressure reading looks like a problem.  Parser got 98.194 and the station is showing 29.69??? 

    I don't know if these variances would affect irrigation schedules or not, but anyone looking at the log might be concerned.

    I notice that the parser is hard coded for gathering solar radiation from the weather station.  Is this value being used by RainMachine to compute ET or is it using the ET value from the weather station?  (Or, perhaps RainMachine is using the solar radiation value from some other reason??) The Davis weather stations can compute ET from solar radiation or from UV radiation depending on which sensor the station is configured with.  I would prefer that RainMachine use the Daily ET value that is downloaded from the weather station.  Is this possible?

    Davis weather stations users have the option to use solar radiation or UV radiation sensor for the purpose of computing ET.  Also, they can use moisture sensors to report soil moisture.  Some irrigation control systems use soil moisture readings from the Davis weather stations to control irrigation.  You should consider building in the capability to use the moisture sensor data from the Davis weather stations.
    Perhaps the settings for the weatherlinkip parser should provide for enabling solar radiation, UV radiation and moisture sensor data collection.

    The parser is hard coded for an interval of 6 * 3600.  Is this 21,600 milliseconds or 21.6 seconds or is it some other period of time?  Would it be possible to allow this to be set by the user?

    It looks like we are very close to having this working.

    Thank you for working on this.


     

  • Avatar
    Nicholas

    Station sends barometer pressure in inchHg we convert it to kPa and looks like it's a correct value. The interval is 6 hours, you could lower by editing the file to 1 hour  (1 * 3600) 

    anything lower than that won't help much since the RainMachine mixer runs on hourly intervals.

    Solar Radiation is added as an option on the parser because I've seen many station report bad radiation which result in wrong ET values.

    As for the moisture sensors, this could be interesting but apart from expensive professional sensors none of the rest actually give useful readings.

     

  • Avatar
    noopara

    Thanks for your quick response and the explanations.

    I first came up with the conversion to 6 hours but didn't think that the interval could possibly be that long.  The weather here in western Washington and a lot of other locals can change a lot in 6 hours.  Would there be a problem if it was changed to 300 seconds?   I would like to stop irrigation as soon as possible with a heavy rain fall. 

    With regard to the solar radiation and ET values from the weather station, does RainMachine use the ET value from the station only if the solar radiation value from the station is within some range and then if it is not, use an Internet or historical value?  Some Davis weather station users don't have a solar radiation sensor.  Instead they have a UV sensor.  A Davis weather station will use which ever sensor is installed.

    I agree with your comment about moisture sensors in that most of them are not very reliable.  I have tried using them over the years and have always been disappointed with their performance.  My suggestion was for the benefit of others that may have had better luck with them.  

     

     

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