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Subject: RE: Proposed change in asyn - request for comments
From: Mark Rivers <rivers@cars.uchicago.edu>
To: "'Eric Norum'" <eric@norum.ca>, "Ernest L. Williams Jr." <ernesto@slac.stanford.edu>
Cc: EPICS Techtalk <tech-talk@aps.anl.gov>
Date: Wed, 30 May 2012 16:03:09 +0000
> I think that you'd be better off setting the waveform record TSE=<the number of 
> some event in your timing system event receiver associated with the pulse>.  
> The waveform record would then get its time stamp from the event receiver.  

I agree that they should set TSE=Event number.  But the question is, how to get the correct value for TSE into the waveform record in a robust way.  Let's assume these are images being collected with an areaDetector camera.  They may be buffered in the driver and plugins for a few LCLS pulses before the waveform record finally processes.  If the waveform record then tries to read the current event number it will not be correct.

It seems to me that the low-level camera driver should be collecting the bunch number the instant the image is collected, and attaching it to the image.  That information should make it back with the image in the callback to the waveform device support.  So maybe it makes sense to not only have a timeStamp passed in the pasynUser, but also a TSE?

Mark


-----Original Message-----
From: Eric Norum [mailto:eric@norum.ca] 
Sent: Wednesday, May 30, 2012 10:24 AM
To: Ernest L. Williams Jr.
Cc: Mark Rivers; EPICS Techtalk
Subject: Re: Proposed change in asyn - request for comments

On May 30, 2012, at 8:07 AM, Ernest L. Williams Jr. wrote:

>> 
> 
> Hi Mark,
> I apologize for the late response.
> Here at the LCLS we are indeed interested in this.
> 
> We rely on our pulseID or "beam flavor" for correlation on a pulse by pulse basis.
> This will be useful for any piece of data acquisition hardware which has an asyn driver.
> For example, if I wanted to use your ip330-asyn driver for beam synchronous acquisition (BSA)
> 
> I hope to encourage more asyn-based drivers here at LCLS but we do need the capability to grab the pulseID
> with the "TSE = -2" technique.  :)
> 
> At this time, there are 2 waveform digitizer VME boards that we have started to work on:
> (1) Struck SIS3350
> (2) Struck SIS3302
> Can we make these asyn drivers and still integrate with GTR?  Eric any comments?

I don't see how GTR and ASYN would go together very easily.    Also, I don't think that TSE=-2 is the right choice for this setup -- the digitizers don't supply the time stamp.  I think that you'd be better off setting the waveform record TSE=<the number of some event in your timing system event receiver associated with the pulse>.  The waveform record would then get its time stamp from the event receiver.  If other records associated with the pulse use the same TSE field then they and the waveform record will have exactly the same time stamp for each pulse.

> If the driver is indeed asyn, we like the proposal for getting the pulseID that you mention above. :)
> 
> I wonder how Jeff Hill (LANL) will correlate his data at LANSCE?
> 

-- 
Eric Norum
eric@norum.ca






Replies:
RE: Proposed change in asyn - request for comments Allison, Stephanie
Re: Proposed change in asyn - request for comments Bruce Hill
References:
Proposed change in asyn - request for comments Mark Rivers
Re: Proposed change in asyn - request for comments Ernest L. Williams Jr.
Re: Proposed change in asyn - request for comments Eric Norum

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