From: Stephen Lewis <stephenalewis@mac.com>
To: "image-slac@lists1.slac.stanford.edu"
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Date: Fri, 1 Oct 2010 13:02:15 -0700
Subject: Re: EVR and cameras
Thread-Topic: EVR and cameras
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If all you require is a good TTL trigger than you don't need the EVR on the=
 same chassis.  However, if you want to use the BSA ('Beam Synchronous Acqu=
isition') technique (from Stephanie Allison) than you do, because the camer=
a records must be directly linked to the EVR records.  If the EVR and its r=
ecords are on a different machine, it doesn't work.  Even so, the TTL trigg=
er still really causes the camera to acquire the image.

MCC scientists use the BSA technique a lot; but if you are in a test facili=
ty maybe your end users do not.


On 1 Oct 2010, at 11:20 , Alison Chaiken wrote:

> Steve, in examining your attached slide, I'm wondering whether EVR cards =
must be plugged into the same chassis as framegrabbers or no.    Wise cowor=
kers have advised me that the same PCI bus must host both cards in order fo=
r the timing system to work properly, although if the camera gets a TTL tri=
gger from the EVR, it's not obvious to me that it's necessarily so.    I gu=
ess that the timing system pulses can be much more frequent than the camera=
 acquisition due to long exposures so that some care is necessary to figure=
 out which events result in initiation of an image acquisition, but I'm not=
 clear on whether there's something special about the two cards being on th=
e same PCI bus if a TTL trigger is still needed.    I'm still designing my =
system and am trying to understand what my architectural options are.   Tha=
nks!
>=20
> --=20
> Alison Chaiken				alison@slac.stanford.edu
> (650) 926-2755 [checked nearly never]	http://exerciseforthereader.org/
> I've got stacks in my structs, I've got arrays in my queues,
> I've got the segmentation-violation, core-dumped blues.
> -- Rick Moen
>=20
>=20
>=20
> <EVR_Camera_timing_LCLS.pdf>