Experimental Physics and
Industrial Control System

"Dalesio, Leo" <[email protected]> · Thu, 21 Oct 2010 08:53:18 -0400

And there is 32 bits for user specification - so the new time format is
64 bit seconds, 32 bit nsecs, 32 bit user

-----Original Message-----

> To sum up the type aspect:
> - A pair of integer is required&  signed integers are good enough for
now ... provided that UINT32 support is completed within the next 68
years.
> - Relative time (pulse time), with ns precision can fit in a FLOAT64
for 125 hours or something like that, which would be OK for us.
> - A ns precision for a software interrupt is somehow excessive and
microsecond precision would fit into a FLOAT64 mantissa but it's not
very good to have many resolutions.
>
> We are considering a waveform with 2 ints for time PVs and maybe
FLOAT64 records for relative time (pulse time).
>
> I also guess that pvData will/shall allow time struct with ns
fractions in the API.
>
pvData defines a timeStamp that is similar to epics except that seconds 
after epoch is

1) An 64 bit signed integer rather than 32 bit signed integer. This 
prevents overflow for a really really long time.
2) epoch is posix epoch (Jan 1 1970 at 00:00:00 UTC) rather than epics 
epoch (Jan 1 1990 at 00:00:00 UTC)

The nanoseconds within the second is a signed 32 bit integer.

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System