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Have you ever seen an irrigation system running in the rain? My neighbor's
do, but mine doesn't. I believe I've already saved 100's of dollars by not
watering needlessly. This is Irrigation Control 1, since I'm pondering a version
2, but I'm not telling
what all version 2 will do yet.
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Basic Idea
This is a pretty simple implementation. Accumulate weather data from the
internet via the host PC. Look at the forecast and historical data. Enable or
Disable the irrigation control with an X-10 module that provides bare
contacts. These contacts are used to close (or open) the ground path to the
solenoids. The standard irrigation controller is programmed to run normally,
and the PC prevents the valves from opening when conditions warrant it. The
hard part is to find an internet site where you can get reliable weather data,
and of course the best logic to enable/disable the valves.
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Block Diagram:
Bill of Materials:
Reference:
Many systems already have a "rain sensor" that will disable the
irrigation system. These are usually based on something like a sponge in a
bucket with a hole. This catches and holds the water, attempting to simulate the
slow rate at which it soaks into the soil, evaporates, and drains away. There is
a switch of some sorts - typically a micro switch. As the sponge soaks up the
water, it swells and triggers the switch. This switch either
provides the signal to the controller or simply opens the ground path to all the
solenoids. This usually means that the controller is running normally, it just
doesn't know that no water is flowing. When the small sponge dries, it shrinks
and the switch changes back to a closed position. Simple. Except they don't
predict the weather, they often require adjustments as they age, and I found
they just aren't that able to do what I want to do.
Implementation:
Weather data is acquired with a simple
Perl script run automatically every few hours. It then looks at the temperature,
wind, humidity, trends and forecast information to enable or disable the system.
With the data supplied online in a consistent format, it is easy to write your
own rules!
With the UM506 device, you simply wire it to open the ground path.
Alternately, you could use a simple appliance module and plug the irrigation
power supply in to that. The downside of this latter approach is that the
irrigation will run solely on the batteries during that time and you'll end up
changing them more often.
Prerequisites
- Installed and operational web server
- Perl installed and configured to serve CGIs from your web
- Geo::Weather module in Perl
- Chart::Composite module in Perl
Download the Perl Script and the sample configuration file
Irrigation1.zip
Containing:
wx.pl (which should be installed in d:\Spool\WeatherData , for minimal
customization. This is the program to acquire the weather information, and
make the irrigation decisions.)
wxreport.pl (which should be installed in your web server cgi-bin folder
X10 Interface
This gives you access to the Firecracker interface needed to control the
irrigation system, and a general purpose X-10 Web interface for anything
else you'd like to control.
Configure the Script
Each Script has a number of configuration options. Each should be
reasonably self-explanatory, and they are at the top of the file. Perl scripts
are delivered in source format, so you can just edit it with Notepad. If you
install just as noted in this document, you'll face the minimum number of
changes to make it work for you.
Use Task Scheduler, and create a schedule to run wx.pl every 2 hours.
Configure your irrigation system on its schedule, but set it to start just a
few minutes after this script runs. In that way, it will have the most up to
date forecast to manage the irrigation cycle.
License Agreement
This program is Webware. You may install it, test it for a reasonable
period of time, and even modify it, but if you elect to keep it in use,
whether in original form or in a modified form, you are then obligated to pay
on a scale based on the value you receive from it. You are not allowed to
redistribute any modified copy.
As with other license agreement, this program is supplied as is, and is not
guaranteed free from defects. You assume all risk for problems you may incur
as a result of the use of this program.
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