This UTC strategy also means that data files designated to cover a certain period may not APPEAR to be created and closed at the correct time, even though they are. Furthermore, using the client-server version of the ODBC driver, it is not even guaranteed that the server and the client are located in the same time zone (though they probably are), so timezone calculations on the server may be misleading to the client. This is because ODBC is also used by IGSS itself, so it must follow the internal IGSS rules for timestamps, meaning it must show values in UTC. Inside IGSS, all timestamps are in UTC, but when data, like logged values and alarms, are made available to the user, the timestamps are recalculated in local time so that the user can understand and relate to them, without having to do manual time calculations.īut in the ODBC driver, for instance, the timestamps are NOT shown in local time, they are shown in UTC, exactly as they are stored inside the IGSS database. UTC is the best choice for timestamping, as Windows today offers functionality to make UTC available to programs together with local time which is actually calculated as an offset from UTC. UTC is the universal time, which is equal to Greenwich Mean Time, only it does not follow the changes in daylight saving time. Inside IGSS all timestamping is done using UTC. BUT before you choose, here are a few things to consider. What time and time zone do you choose to set on the PCs running IGSS ? Easy question – they should all be set to the same local time, of course, and the time zone should be set to whatever zone the PC’s are in.
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