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goeh / weather-collector

This Java program read data from a weather station (Davis Vantage Pro2) and store it in a SQL database
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All data in weather station is downloaded, instead of last hour #18

Closed goeh closed 3 years ago

goeh commented 3 years ago

During testing I set "LastRecordTime" to one hour ago. But I keep getting ALL data from the weather station. It taked 10+ minutes to download all data.

goeh commented 3 years ago

The answer is in the Vantage 2 Serial Communication Reference Manual: "In order to use the "DMPAFT" command you need to determine the time and date-stamp of the last record that you already have, AND this record should match one of the records already archived in the WeatherLink data logger. (if the data is not found, then the entire contents of the data archive will be downloaded.)"

Thus when testing with an arbitrary timestamp 60 minutes ago, the chance of finding a record with that timestamp is minimal. So when testing you have to dump all records first, then make a note of a valid timestamp and use that for testing. Data stores that persist the last downloaded timestamp do not have this problem. For example SqlDataStore.

goeh commented 3 years ago

Now that the test timestamp is truncated to hours, a matching records is often found. Closing issue.