Dear SalemBottomWeather, Herb, Blick, AssortedNuggets, and WeatherCat Davis fans,
Since you went into great detail in your questions, let me try to answer them in detail. I'm not the WeatherCat developer, but I'm a longtime user with a Davis Vantage Pro-2.
*) Does WC only query the Logger at startup?and only if some amount of time has passed since the last query? How much time needs to pass?
In short yes. If WeatherCat is running, then it gets current conditions directly from the station so there is no need to involve the data logger. The amount of time needed before it will query the data logger depends on sampling rate for WeatherCat (see preferences/misc2.) So if you have your sampling rate set to 5 minutes and you quit WeatherCat for less than 5 minutes, WeatherCat will not need to sample the data logger.
*) Is the most the most recent hour retrieved? When I view the data in the DataViewer, the most recent hour is always missing.
I'm not sure what you mean by this. What is the sample rate you have chosen?
*) If the ?Delete Log After Historical Download? is *not* checked, does it download the entire contents of the logger each and every time? Because it takes 3 or 5 minutes to complete and runs through all 512, I suspect this is what is happening.
In short yes. The data logger is in effect a circular buffer. WeatherCat downloads the entire logger and then compares the timestamps of the data it already has to the contents of the logger. It then matches up what is missing from the WeatherCat data and fills the missing portions from the data logger.
*) If the ?Delete Log After Historical Download? is checked, does WC perform any kind of verification that it has successfully pulled all data before deleting? Otherwise, any data that may have been lost in transmission (and not successfully downloaded) would be erased.
I don't believe WeatherCat does this, but there is no reason to delete the data logger during normal operation. The only reason purge the data logger is if you suspect there is some corrupted data. Another time you might want to do this is if you have performed some maintenance on your station that might have introduced erroneous data. Corrupted data loggers are extremely rare. I'm not aware of any WeatherCat user ever having this occur and my station is over 5 year old now.
*) Let?s assume WC has *not* been running for 4 or 5 days (and assume that the DataLogger is not ?full?): will WC retrieve all data stored in the logger or just the last day or two?
As I said, WeatherCat will not purge the logger unless you explicitly request it to do so. WeatherCat retrieves all the data, but then matches that data to what is missing and only adds what was not already existing to the WeatherCat database.
*) Are there any known reasons why or when WC would not retrieve data from the Logger?
You could ask the WeatherCat developer for full details, but the only reason WeatherCat wouldn't download data is some sort of malfunction which are vanishingly rare.
First, I do not intend to run WeatherCat 24/7?.rather use it to pull down the saved data from the logger and then run reports, plots, and charts. Will also be viewing the live stream but will be running WC 4 or 5 times a week; each session lasting anywhere from 5 minutes to a couple of hours. One of my primary objectives is to build and maintain a complete historical record.
Most of us do not run our stations like this because it limits what WeatherCat can do. However, when our house was damaged by a lightning strike, I was forced to download data periodically as you propose for about a week until I was able to make repairs to my data connection. WeatherCat performed as you desire it, perfectly. I lost no data by allowing my Davis station to store the conditions in the data logger and then running WeatherCat periodically to download the data onto my Mac. You can set up your station in this way in full confidence.
Cheers, Edouard