VI to convert LabVIEW time to Unix time

[davida2000]

Does anybody know of a VI to convert LabVIEW time to Unix time?

[KileenC]

There aren’t any VIs already available to convert LabVIEW time into Unix time. Currently, the LabVIEW Get Date/Time in Seconds.vi returns a time stamp of the current time, measured as the number of seconds that have elapsed since 12:00 a.m., January 1, 1904, Universal time. As far as I know, the unix timestamp is based on seconds since standard epoch of 1/1/1970. The conversion to unix time would not be too difficult; essentially you would just want convert timestamp all to seconds and then subtract the number of seconds from 1904 to 1970.

An alternative approach would be to see if there’s a shared library (or DLL equivalent) on the unix OS that will return the unix time.

Hope this helps. Best of luck!

Kileen

[Odd_Modem]

This could be an entertaining project. I think times are stored based on GMT, then there is an offset local to your computer which puts the sun in the right part of the sky, for where you are. At least it seems that way with Microsoft time. Is Unix time really POSIX time? I see a POSIX manual at the very end of my bookshelf...

Time is number of seconds since midnight January 1, 1970

Coordinated Universal Time

(GMT). It would be interesting to find out how to discover the timezone offset of the local computer; it seems like its hardware specific.

[StevieZ]

I've created a VI that does just this and posted it on the community examples. You can view it at http://decibel.ni.com/content/docs/DOC-3644.

Basically to get around the timezone issue that Odd_Modem pointed out it queries the timezone data from the kernel32.dll in windows then subtracts out this offset.

Regards,

Steven Zittrower

Applications Engineer

National Instruments

http://www.ni.com/support

[ceger]

StevieZ, I don't believe your method is necessary.  That is, there isn't a "time zone" issue to deal with.  I've attached a VI that demonstrates this.

[TCPlomp]

Here is a simpler (and OS independent) method to get the timezone offset.

Ton

[ceger]

Very nice, Ton.  But what I'm attempting to demonstrate is that the timezone offset is not needed if one is simply trying to determine the current Unix (POSIX) time.  All that is needed is to subtract a constant, timezone independent value from the LV timestamp.

[rolfk]

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ceger wrote:
Very nice, Ton.  But what I'm attempting to demonstrate is that the timezone offset is not needed if one is simply trying to determine the current Unix (POSIX) time.  All that is needed is to subtract a constant, timezone independent value from the LV timestamp.

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Indeed and you can determine that offset once and then use it as a simple numeric in all your diagrams.

For the curious ones the interesting part that ceger refers to is all at the right border of his VI in the box. What you see there is all that is needed to convert LabVIEW time from its epoch into a different epoch.

Message Edited by rolfk on 10-13-2009 08:09 AM

[TCPlomp]

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ceger wrote:
Very nice, Ton.  But what I'm attempting to demonstrate is that the timezone offset is not needed if one is simply trying to determine the current Unix (POSIX) time.  All that is needed is to subtract a constant, timezone independent value from the LV timestamp.

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Yes I know, I was posting the code to provide a non-os dependent way to get the timezone offset.

Especially since the Windows version came from an NI member.

Ton

[md71]

Hi,

I need information for convert LV Date/Time to Unix time on sbRIO9631.

I have seen the example, but I have a different time between PC and sbRIO (sbRIO: 2010/04/09 07:22:33 and PC: 2010/04/09 16:22:33).
I need to synchronize the time!

If anyone can help?

Thanks a lot!

md71