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Subject: RE: synchronizing data to an event
From: "Pearson, MR \(Matthew\)" <[email protected]>
To: "Ralph Lange" <[email protected]>, <[email protected]>
Cc: EPICS Tech Talk <[email protected]>
Date: Wed, 7 Nov 2007 15:30:15 -0000
Hi,
 
There's been a lot of work at CERN in this area for the LHC experiments. They are currently commissioning a fibre optic "timing, trigger and control" system. It broadcasts timing information (bunch freq and orbit freq) multiplexed with addressable trigger and control signals (like 'reset', 'flush buffer', etc.). The trigger/control signals can be addressed to sub-systems of each main detector (like silicon tracker readout system, muon chamber readout system, etc.).
 
It provides the means to tie each data structure collected to an event number (collision, or bunch in synchrotron world), as well as distributing a trigger to multiple systems.
 
There's more info at:
 
(lots of papers and references at the bottom)
 
Cheers,
Matthew Pearson
DLS Controls


From: [email protected] [mailto:[email protected]] On Behalf Of Ralph Lange
Sent: 07 November 2007 14:57
To: [email protected]
Cc: EPICS Tech Talk
Subject: Re: synchronizing data to an event

Hi Ron,

the latest publication on the LANSCE (Los Alamos, not SLAC) "flavored beam" issues is Jeff Hill's poster/paper at the ICALEPCS a few weeks ago.

Hope this helps...
Ralph


Ron Rechenmacher wrote:
Hi,

I did a search of tech-talk for: timing event synchronization
The results along with my experience to date leads to the conclusion
that synchronization by 8 byte time stamp is the only synchronization that
CA currently provides. (please correct if wrong)

The question:

  I was wondering if there has ever been any (perhaps behind the scenes)
  discussion of adding additional synchronization information to the
  Channel Access protocol?


Perhaps, in addition to the timestamp, a "synchronizing event" structure, 
which would be NULL if not used, but would otherwise have an event type and 
event count.

At some linear accelerator facilities, there has been a move toward counting 
RF pulses and associating data collection triggered by the RF pulse with that 
pulse count.  Of course there would be a pulse count to time correlation also,
but many people seem to embrace the main data association (in archived data) 
being with an event count.

I've heard that there has been work on "beam flavors" at SLAC. (sorry if this 
is bogus information). But if in addition to a timestamp, data also has 
"flavor" information, then this could be considered a start to additional 
synchronization information?  Has there been work on this? and if so, has any 
progress reports been published?

Thanks,
Ron
  
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References:
synchronizing data to an event Ron Rechenmacher
Re: synchronizing data to an event Ralph Lange

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