Experimental Physics and Industrial Control System
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Emmanual,
I'm not sure why you say "epics can only process the information at a
maximum rate of 10Hz." I think this surprises alot of people that have
been processing data at 60Hz or 100Hz (or faster) for several years.
If you are referring to the default selections for periodic scanning,
10Hz is the limit. Interrupt driven records, or software event driven
records can scan as fast as your processor allows. If you need to
capture a value each time the record processes, you may need to do this
within the IOC (rather than trust a CA client to keep up), but there
are lots of ways to do this as well. Some custom records I know of
capture data at 60Hz, but average N consecutive samples and post this
averaged data to CA clients at a much slower rate. The pulse to pulse
data is available if you want it as well.
As far as "synchronization and data processing", in our linac the frame
grabber data (processed at up to 60 Hz) can be correlated to the RF
data for a particular beam pulse via timestamps even though they come
from different IOCs. You would need some event system hardware for
this, however.
Ned
Emmanuel Mayssat wrote:
I am actually doing something quite similar, but I am using a standard
camera with a frame grabber.
The issue I am facing is related to synchronization and data processing.
For example I calculate the x and y profiles of a electron beam.
But while I can acquire image at 30Hz, epics can only process the
information at a maximum rate of 10Hz.
Is there a work around?
Is it possible to do real time video with epics?
n Wed, 2005-11-16 at 13:44 +0100, Aladwan Ahed wrote:
Hi Matjaz,
At the SLS we interfaced CCD cameras with Firewire bus to EPICS (3.14.7 on Linux RH7.3), you can find all the info and the source code under:
http://epics.web.psi.ch/software/firewire/
We think Firewire is a good choice as it supports isochronous data - delivering data at a guaranteed rate. This makes it ideal for devices that need to transfer high priority data in real-time, such as video devices. It is also fast (400Mbit/sec) (53 frames/sec @ 1Byte and 1024*768 pixels and 80% usable bandwidth), actually, this is more than what the EPICS video server PC can process. The EPICS video server grabs the frames from the camera, process them, and then allow any CA enabled client application to access the processed data, this way we save our network bandwidth.
Cheers,
Ahed
###########################################
# Ahed Aladwan
# SLS Controls / Paul Scherrer Institute
# WSLA/208, 5232 Villigen PSI Switzerland
# Tel:+41 56 310 4594
# Fax:+41 56 310 4413
# www.psi.ch
# http://people.web.psi.ch/adwan/
###########################################
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ANJ, 02 Sep 2010 |
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