If I use Now() to retrieve a TDateTime value I get it in whatever timezone (including DST) the box I run on is set to...
And there is no indication of the timezone used (TDateTime is just a double after all).

So now I wonder if there is some kind of globally constant time one can read which can be used in scheduling applications no matter what time zone is used. For example something like NowUTC() or similar?

I have been struggling with the user part of a remote monitoring system, which will run on a RaspberryPi under Linux (Debian flavour).

And there are lots of problems when going between the actual remote system and the config application because of the time zone differences. It would help a lot if one could use a time that is not messed with and is the same everywhere...

The important thing here is that two systems located at different places on Earth should agree on such a time value if it is taken at the same absolute instant.

And what is the useful resolution of the times?
seconds, miliseconds or what?

You can use LazSysUtils.NowUTC, and then there is also PascalTZ package if you want to convert between timezones.

There is a ticket with a patch for adding a similar function to FPC, but it needs some attention:
https://bugs.freepascal.org/view.php?id=30394
<https://bugs.freepascal.org/view.php?id=30394>

Regards,
Denis

I'm terribly sorry, I totally forgot about this bugreport :/

But Ondrej Pokorny has meanwhile implemented NowUTC and other related functions that allow more flexibility regarding the timezone.

So, Mr. Berglund, with FPC trunk, your problem will be solved. I'm not sure it will be in 3.2.2, because it is rather sensitive.

Michael.

Op 2021-05-03 om 20:28 schreef Michael Van Canneyt via lazarus:

Indeed, it (r47306) /won't be in 3.2.2

I only run with released versions so I will wait until then. I guess I can always do this to get an UTC timestamp:

function MyNowUTC: TDateTime;
begin
  Result := LocalTimeToUniversal(Now);
end;

Now I am at least running an UTC clock on screen using this call.