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FAQ: Difference between revisions
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→How does Cumulus handle Daylight Saving Time?
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== How does Cumulus handle Daylight Saving Time? == | == How does Cumulus handle Daylight Saving Time? == | ||
Cumulus provides the option for you to use rollover at 9am winter time that is preserved throughout the year so all days are 24 hours long even when clock changes, simply click "Use 10am in summer" on the Station settings. | |||
As far as the timestamps in the extreme logs, monthly log, and the graphs, are concerned; Cumulus doesn't do anything in particular for DST. | As far as the timestamps in the extreme logs, monthly log, and the graphs, are concerned; Cumulus doesn't do anything in particular for DST. | ||
*It generates timestamps based on the | *It generates timestamps based on the clock in the device you run Cumulus on. | ||
**So basically, at the start of DST (i.e. when the clocks 'go forward' for the summer) you will get an apparent gap of one hour in your data logs and on graphs. | **So basically, at the start of DST (i.e. when the clocks 'go forward' for the summer) you will get an apparent gap of one hour in your data logs and on graphs. | ||
**Similarly at the end of DST (i.e. when the clocks 'go back' for the winter) you will get an apparent hour of duplicate timestamps in your logs and graphs. | **Similarly at the end of DST (i.e. when the clocks 'go back' for the winter) you will get an apparent hour of duplicate timestamps in your logs and graphs. | ||
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**This is because the console memory does not time-stamp the data blocks and each memory location simply contains the number of minutes elapsed since the previous memory location was last updated. | **This is because the console memory does not time-stamp the data blocks and each memory location simply contains the number of minutes elapsed since the previous memory location was last updated. | ||
**Cumulus does not remember the console data block used just before shutdown, (after all depending on how long Cumulus has been stopped and the station logging interval, the old memory location could be overwritten by now), and so Cumulus works out a time-stamp based on current clock time and the stored elapsed interval times as it works back through those memory locations. | **Cumulus does not remember the console data block used just before shutdown, (after all depending on how long Cumulus has been stopped and the station logging interval, the old memory location could be overwritten by now), and so Cumulus works out a time-stamp based on current clock time and the stored elapsed interval times as it works back through those memory locations. | ||
**The stored minutes elapsed value will be consistent with the logging interval you selected for the station (might be different to that selected on Cumulus) and | **The stored minutes elapsed value will be consistent with the logging interval you selected for the station (might be different to that selected on Cumulus) and that stored value will add an extra minute if a read from the transmitter (every 48 seconds on models without solar sensors) delays a particular log update, However, the console clock (unless radio-controlled) is unaware of DST, it is like a clock without a hour hand, it can only count in minutes. | ||
**On restart Cumulus just tries to read the appropriate number of hours worth of observations back from the block now marked as latest. | **On restart Cumulus just tries to read the appropriate number of hours worth of observations back from the block now marked as latest. | ||
**For example if it was stopped at 2200 DST and restarted at 0600 standard time, Cumulus catches up with the last 8 hours worth of stored measurements as if going back to 2200 standard time, that means it retrieves back to 2300 DST and has forever lost the period 2200 to 2300 DST. | **For example if it was stopped at 2200 DST and restarted at 0600 standard time, Cumulus catches up with the last 8 hours worth of stored measurements as if going back to 2200 standard time, that means it retrieves back to 2300 DST and has forever lost the period 2200 to 2300 DST. | ||