Experimental Physics and
Industrial Control System

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<== Date ==>		<== Thread ==>

Subject:	Re: pyEpics time stamps
From:	Eric Norum <[email protected]>
To:	EPICS mailing list <[email protected]>
Date:	Mon, 12 May 2014 16:39:42 -0700

I’ve found the problem — the code in lib/dbr.py looks just plain wrong:

EPICS2UNIX_EPOCH = 631173600.0 - time.timezone

. . .

def make_unixtime(stamp):

    "UNIX timestamp (seconds) from Epics TimeStamp structure"

    return (EPICS2UNIX_EPOCH + stamp.secs + 1.e-6*int(1.e-3*stamp.nsec))

Problem one — that constant is wrong. The correct value, as defined in <base>/include/epicsTime.h is: #define POSIX_TIME_AT_EPICS_EPOCH 631152000u

Problem two — what’s ‘time.timezone’ doing in there? The unix time stamp is in UTC as is the EPICS time stamp.

I propose the following fix:

diff -u lib/dbr.py.orig lib/dbr.py

--- lib/dbr.py.orig 2014-05-12 16:37:58.000000000 -0700

+++ lib/dbr.py 2014-05-12 16:38:00.000000000 -0700

@@ -66,7 +66,7 @@

 MAX_ENUM_STRING_SIZE = 26

 MAX_ENUMS            = 16

-EPICS2UNIX_EPOCH = 631173600.0 - time.timezone

+EPICS2UNIX_EPOCH = 631152000.0

 # create_subscription mask constants

 DBE_VALUE = 1

Who’s maintaining the pyEpics stuff now?

Replies:: Re: pyEpics time stamps Mark Rivers; Re: pyEpics time stamps Matt Newville

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ANJ, 17 Dec 2015