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

Subject: Re: RE: Waveform Record Device Support
From: nda@aps.anl.gov
To: graham.cox@stfc.ac.uk, tech-talk@aps.anl.gov
Date: Tue, 8 Jun 2010 10:28:57 -0500 (CDT)
>Thanks for the replies.
>
>
clip ...
>As a follow up question, what would be the recommended way of performing
>calculations on array data within the EPICS database?  Do I have to
>resort to subRoutine records?  In my individual channels of data
>(subArray records) I have multiple quartets of data, one for for each
>turn captured, I need to perform calculations on each of these quartets
>to determine beam position for each turn.

You may want to look at this work of using Octave in an IOC by Miroslaw ...

http://www.aps.anl.gov/epics/meetings/2007-04/e138/Octave-iocHamburg.pdf



>
>Thanks,
>
>Graham
>
>-----Original Message-----
>From: emmanuel_mayssat@lynceantech.com
>[mailto:emmanuel_mayssat@lynceantech.com] 
>Sent: 07 June 2010 22:39
>To: Cox, Graham (STFC,DL,EID)
>Cc: tech-talk@aps.anl.gov
>Subject: Re: Waveform Record Device Support
>
>On 10:06 Mon 07 Jun     , graham.cox@stfc.ac.uk wrote:
>> I am integrating a turn-by-turn BPM system into EPICS and would like 
>> to store the raw BPM pickup data in a waveform record.  Due to the 
>> nature of the system, each run can result in a different number of 
>> samples for each BPM pickup, so the array size is unknown in advance 
>> and could potentially be different every run.
>
>Given my limited experience with particle accelerators, I am just
>wondering what kind of system are you working with?
>Storage ring, linac, ... pulsed, not pulsed?
>If the waveform length is changing, it can only be because data
>acquisition is asynchronous.
>Are you sampling CW signals? I can't think of a system that would work
>with those requirements.
>Could you expend?
>
>> Is it possible to resize the number of waveform record elements in my 
>> device support, or do I have to size the waveform record in advance 
>> for the maximum number of samples that could be expected.  Most of the
>
>> examples of waveform device support I see read the nelm field and 
>> return this fixed amount of data via the records bptr.
>
>Another solutions may be to use FIFO waveforms, aka compress records.
>The compress record is part of epics-base.
>In this case, the number of samples per channel acquired can be
>different, but the length of the FIFO stack can be the same.
>
>Good luck,
>
>--
>Emmanuel
>-- 
>Scanned by iCritical.
>


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