On Monday 25 June 2012 11:50:53 Matt Newville wrote:
> > http://131.193.191.37/~mnm/temperatures/menu.php
>
> That looks nice. I like the interactive zooming, but I'm not exactly
> sure I understand what I'm looking at. For me, the plots seems to
> dance around quite a bit, sometimes showing a long history of a couple
> temperatures, sometimes showing nearly nothing... Maybe I'm not using
> it correctly?
It does behave properly only in Chrome -Safari and Opera.
The first row of buttons shows the last X minutes or hours of data auto
refreshing every second.
The big check button that says "Realtime data feed" switches that
functionality on and off.
The experiment is over and there is no data being collected anymore.
Overall if there are no dancing graphs double click would re-zoom to the
entire time interval and mouse dragging region of the graph or clicking on
some of the tooltips would zoom on that region.
The interface is not completely full-proof and light and I am
in process of rewriting the whole front-end completely making it robust
and applicable for more general use.
> If you're using PyVisa to read the meter over GPIB/USB, that suggests
> these temperatures are not Epics Variables. Is that correct? You
> can run a Keithley meter with Epics and read the temperatures with a
> Channel Access client at fairly high speed. Is this something you are
> doing, or have in mind to do?
My experiment at UIC is using epics soft ioc running with 2 PVs. Keithley 2000
and animatics smart motor and tha's how I do it there.
I used the PyEpics wit the on changes callback.
Unfinished poster type presentation for that experimental setup.
http://miro.phy.uic.edu/~mnm/jquery/poster/#section11
I had no intention to do any of that visualization while at the beam-line.
I had some code from before where reading GPIB with python and writing
the value every second to a file. So no effort while setting this part.
At some later time I decided to try to writing remotely into the database
the computer at UIC my laptop while at the beam-line.
I realized that although not in the same subnet I still could insert data at
rate 10Hz.
So I just adopted the python script that I use for dumping the PV values
with the onchange callback for my UIC experiment to the existing setup.
More or less cloned and stripped down the application that I already have.
So if I were to have this web application written in a bit more general way.
I could have started visualizing the historical data immediately with no effort
on the setup part.
> > In general there is a need for visualization of real time data in the
> > scientific community. However setting up and maintaining the
> > infrastructure is not a trivial matter. With this kind of centralized
> > system this problem could be significantly reduced.
> > For example for an EPICS environment such as the beamlines at APS the
> > task of visualizing small number of PV s could be reduced down to
> > running a simple python script on the client machine given that pyEpics
> > installed on the client machine. The database server has to be setup
> > only once at one location.
> > My rough estimate is that a single modern desktop system can serve tens
> > of clients simultaneously each individually recording at a rate of 10Hz.
>
> Yes, pushing changes in PV values into a database server can go very
> fast. And, yes, using a database backend is a good way to centralize
> data collection.....
>
> Can you give a few more details of what you have in mind? You might look
> at https://github.com/newville/epicsarchiver (for code) and
> http://cars9.uchicago.edu/cgi-bin/pvarch/ (for example installation)
> of a 'python/epics/mysql' data archiver with a web interface. It
> could definitely use some attention especially for faster, more
> interactive web and graphical displays of data, etc. I'm not sure
> it's exactly what you have in mind, but it might be worth looking at.
I was using the epics archiver at the beginning but that project is more
oriented towards storing huge number of PVs while I have only two.
I have adopted ideas from the epics archiver. Such as the database runs.
I was really biased towards the real-time data display and analysis and also
had way to many small requirements specific to my experiment so
at some point I decided to write something on my own.
I think I saw here discussions on topic of archiving PV data.
http://www.aps.anl.gov/epics/tech-talk/2011/msg01681.php
So I guess I was asking about the other projects such as the WebPOI pointed
out by Xihui earlier today.
> Cheers,
>
> --Matt Newville <newville at cars.uchicago.edu> 630-252-0431
--
Miroslav Mihaylov
University of Illinois at Chicago
Department of Physics
2336 SES
845 W. Taylor St. M/C 273
Chicago, IL 60607
312 355 0225
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