Experimental Physics and
Industrial Control System

Kay-Uwe Kasemir <[email protected]> · Tue, 16 Mar 2004 09:19:25 -0700

Hello:

The wonders of the internet! Just came to work, hadn't even reached the 
original question from Wang Yanke, when numerous people had already answered
this.

To summarize the 2 issues:

1) Sampling, time stamps
Pretty much everybody who starts using the archiver comes up
with the "I scan every X seconds but get ... for time stamps"
question.

The explanation was somewhat hidden on the archiver web pages.
The manual for the ongoing archiver update, see
http://ics-web1.sns.ornl.gov/~kasemir/archiver/index.html
now starts with about 10 pages that go into some detail on
what's a channel, when the CA server sends a monitor, how the archiver
deals with the time stamps.

2) Precision on retrieval
It's a loose-loose situation. Some people configure PREC,
others don't, and there's no way to select the commonly
desired options:
- decimal notation 0.0000
- exponential notation, 0.000e000
- engineering notation, 0.000e000,
  with exponents being a multiple of 3, so you effectively get
  ..., nano, micro, milli, .., kilo, mega, giga, ...
Any of those should default to PREC for the # of trailing digits
but allow override.

To keep the generic tools like CGIExport & ArchiveExport simple (or was it lazyness?),
they used the first format & honored PREC.
Whoever wanted more, had to use the scripting or C++ access to the data.

We'll add configuration options for numeric export to the "new"
ArchiveExport and java data client.

Thanks,
-Kay

On 2004.03.16 20:15, Wang Yanke wrote:
> Hi,
>   When I tried to archive the vacuum data with
> ChannelArchiver, I got some data like:
> 
> 03/09/2004 15:58:23.254187014   0.000
> 03/09/2004 15:58:43.254186214   0.000
> 03/09/2004 15:59:00.000000000   0.000
> 03/09/2004 15:59:03.254185414   0.000
> 03/09/2004 15:59:20.000000000   0.000
> 03/09/2004 15:59:40.000000000   0.000
> 03/09/2004 16:00:00.000000000   0.000
> 03/09/2004 16:00:20.000000000   0.000
> 03/09/2004 16:00:40.000000000   0.000
> 03/09/2004 16:00:43.254181414   0.000
> ....
> 
>   I have retrievaled it with CGIExport or ArchiveExport many times, but
> the results were disappointing.
>   So, Why can't I get the same proper value(e.g. 1.324e-07) as using
> "caget" instead of zero?
>   Furthermore, why the time interval is not the value i set in the .cfg
> file(20 seconds)?
>   Is there something wrong with the configuration of the ArchiveEngine
> or the retrieval tools?
>   How can I get the data I want? 
>   Help me, thanks!

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System