My weather station is a solar-powered, wireless Davis Instruments Weather Monitor II. It measures wind speed and direction, rainfall, temperature, and humidity. The station sends its data to a Weather Monitor II console, which measures barometric pressure, inside temperature, and humidity. The console also calculates the dew point and tracks highs and lows.
The station is mounted on an unused chimney, facing south. It sits just above the roofline and is relatively unobscured by trees or other obstructions. Here are some views of the station.
Left and center are two views of the station looking west and east, respectively. Behind the station in the center view you can see my 2 meter/70 cm J-pole amateur radio antenna (I'm KF6YTV). It's made from copper tubing and works pretty well. On the right is a close up of the solar panel that powers the station.
This version of the WM II comes fully assembled, so installation is pretty straightforward. Once I decided where to install it, I used a TV antenna chimney mount kit to mount it.
The WM II console is connected to an iMac DV+ (PowerPC G3 450Mhz, 192Mbytes RAM, Mac OS 9.0.4) using something that Davis calls "Weatherlink". Weatherlink is a data logger with a standard telephone UTP cable coming out of it. This cable is supposed to plug into a modem or, via a cable adaptor supplied by Davis, a Macintosh serial port.
The iMac has no serial port.
No big deal. A Keyspan Twin Serial Adapter works just fine, though for some reason the Weatherlink application just wasn't happy using the emulated serial port on the Keyspan. It liked the emulated printer port well enough, though.
The Weatherlink application program supplied with the Macintosh version of the product is from another era. It does not appear to have been updated in quite some time. It is stuck in a time when modems were either 1200 baud or 2400 baud and USB was just a gleam in someone's eye. Its user interface is woefull. Most horribly, it is not scriptable and it cannot be set up to download the weather data and write it to file on a schedule. The app is designed to draw weather station graphics to the computer screen, not download and prepare the data for upload to a web site on a regular schedule.
This lack of automatic download from the station is in stark contrast to the Windows version, for which a whole toolkit is available for designing weather web pages, exactly what I wanted to do.
I called Davis to see if I could get a copy of the source to the Mac version of Weatherlink. They were quite polite, but informed me that they never give out source. Given the state of the app, I figure that either they lost the source years ago, or they were just plain embarrassed. All I wanted to do was automate the data download and logging to file. All Davis would do was point me to their Developer's kit (which is very helpful, to be fair).
I didn't want to have to write an app from scratch. Then a friend recommended REALbasic®, from REAL Software, Inc. REALbasic turned out to be a breeze to use, even for an unreconstructed assembly language programmer like me. I had a few problems with the object model (I always want to write an app in a straight, procedural line), but it worked. Communicating through the serial port was easy, despite the clear impression I got that was out in REALbasic country where the busses don't run. Of the many, many, REALbasic apps available on the RB website, none, as far as I could tell, used the serial port. I also used a thread in my app, another area where you get a bit of a lonely feeling.
But, amazingly, I was able to write the app in a few evenings. Actually, it's currently a combination of a REALbasic application that contains an AppleScript that writes out the HTML and invokes Fetch 3.0.3 to upload the page. It runs with just a couple of occasional glitches that I'll track down. The point is, the basic function of communicating with the Monitor II weather station, reading the data and writing it to a file on a regular basis, works.
I intend to clean the app up and generalize it some (like not hard-code my website address, for example), and then include it in REAL Software's Made with REALbasic program.
In the meantime, if you would like a copy of the application or have any questions about it, I'll be happy to hear from you. Drop me a line.
