Experimental Physics and
Industrial Control System

"Jemian, Pete R. via Tech-talk" <tech-talk at aps.anl.gov> · Fri, 29 May 2020 22:48:15 +0000

A few APS instruments use this software (perhaps more than I know)

Here's one basic example:
https://8id.xray.aps.anl.gov/pvWebMonitor/8idi/livedata.html
Here's one richer example: https://usaxslive.xray.aps.anl.gov/

Live content from the control system is written to XML files every few
seconds.  You can view those updates by refreshing the browser window as
fast as you wish.  In this example, the content refreshes every 10 seconds.

When you are not pressing F5 to refresh the browser window, the window
automatically refreshes with this directive:

      <meta http-equiv="Refresh" content="300"/>

The value (5 minutes) is up to you.  The thinking is that if you are at
a browser and interested, you may refresh more frequently.  If you walk
away, the screen is at most 5m out of date.  This reduces web server
load when no one is really watching.  In your case, you might set this
number comparable with the interval between updates from EPICS data or
screen shots.

Another page: https://usaxslive.xray.aps.anl.gov/showplot.html
has a different update.  View the page source to see that it is 60s
(1m).  This page is a plot (created by other software but written to an
image file) of the most recent data.  In your case, it would be a screen
(or window) shot written to an image file.  You keep your displays
exactly as they are designed, take automated screen shots somehow, and
post them as updates.

The HTML pages are arranged with XSLT stylesheets.  These XSLT files are
like the screen display files for MEDM, or other EPICS GUI, they show
where to put information on the page.  The XSLT files are updated when
the page needs to be redesigned.

The data is in XML files which are updated as often as necessary.

An HTML file is created by transforming the XML file with an XSLT file.
PvWebMonitor does this with the lxml package.

If you are savvy with CSS, the pages can look much better than these.

Regards,
     Pete

On 5/29/2020 6:40 AM, elio at ugr.es wrote:
> Hi Jemian,
> 
> This is really interesting, but I have a couple more questions. I assume
> that this functionality that you mentioned about serving image files is
> necessary to represent the different graphs and waveforms shown on the
> operator interface (since it is a big amount of data). This implies that
> some modifications will be needs on the mirror side to adapt the new
> operator interfaces by changing graphical displays to image display (losing
> some performance). The refresh time that I have seen on the website is 5
> minutes, which seems to me pretty high if we want to display waveforms and
> this kind of graphics.
> 
> Is it possible to decrease this refresh time? What is the better performance
> that could be achieved?
> Could you provide any reference about facilities using this solution?
> 
> Thanks in advance!
> 
> -----Original Message-----
> From: Tech-talk <tech-talk-bounces at aps.anl.gov> On Behalf Of Jemian, Pete R.
> via Tech-talk
> Sent: jueves, 28 de mayo de 2020 20:14
> To: tech-talk at aps.anl.gov
> Subject: Re: Mirror Control Room
> 
> Another possibility
> 
> 
> 
> https://pvwebmonitor.readthedocs.io
> 
> The python pvWebMonitor package does much of what you describe.  It provides
> a background service that monitors EPICS PVs and writes them into customized
> HTML files in a WWW server directory.  Other files (such as .png, .jpg, ...)
> can also be part of the routine update of the WWW server directory.
> 
> The software creates a static website directory with content you update from
> the control system.
> You need a working web server to serve that content.  The web server does
> not have to be within the control system, just needs access to the directory
> with static content to be served.
> 
> You will need other software to generate screen images and write to disk.
> Then pvWebMonitor can copy that content to the static website directory.
> 
> This satisfies:
> 
> * remote observation
> * no remote interaction or control
> * separation of web server from control system
> * control system values
> * graphics files
> 
> This also means there is some latency between control system updates and web
> site content.
> 
> On 5/26/2020 5:27 AM, Elio Valenzuela via Tech-talk wrote:
>> Hello,
>>
>> I am working at the design of a "mirror control room" of a LINAC in a
>> remote location. The goal is to replicate all the control panels
>> displayed on the facility in a second location on a different country
>> but in a "read only" fashion. We do not have specific requirements
>> about latency of the represented data, so we can decide to represent
>> "offline data"(snapshots taken a few times during the day and sent to
>> the mirror facility with some delay) or "real time data"(each change
>> on a PV is sent automatically to mirror facility). The original
>> facility has a strict separation policy between EPICS network and DMZ,
>> and internet can be reached only from DMZ. The expected bandwidth
>> between the two facilities is around 10Gbps, and the quantity of PVs
>> generated is still unknown.
>>
>> I know that it is difficult to provide an answer with the only data
>> that I provided, but I just want to know if there are other facilities
>> doing similar things to have a reference case to follow. My first idea
>> was based on the use of CA Gateways and try to send in "real time" all
>> PVs to the mirror server, but I think that it is not an standard
>> solution that could be easily accepted by the LINAC organization. Any
>> suggestions about how to implement this edge control room in a safe
>> and efficient manner?
>>
>> Thanks in advance.
>>
>> *Elio Valenzuela Segura*
>> Researcher, Universidad de Granada
>>
>> ----------------------------------------------------------------------
>> ----------------------------------------------------------------------
>> ----------------------------------------
>>
>> Resultado de imagen de citic ugr logo
>>
>> 		
>>
>> *Elio Valenzuela Segura*
>> Researcher, Universidad de Granada
>>
>> +34 958 241 775 <tel:+34%20958%20241%20775> | elio at ugr.es
>> <mailto:elio at ugr.es>
>>
>> CITIC, Calle Periodista Rafael Gómez Montero, 2, 18014 Granada
>>
>> https://dn3tzca2xtljm.cloudfront.net/social_icons/16px/linkedin.png
>> <http://www.linkedin.com/in/eliovalenzuela>
>>
> 

-- 
----------------------------------------------------------
Pete R. Jemian, Ph.D.                 <jemian at anl.gov>
Beam line Controls and Data Acquisition (BC, aka BCDA)
Advanced Photon Source,    Argonne National Laboratory
Argonne, IL  60439                    630 - 252 - 3189
-----------------------------------------------------------
       Education is the one thing for which people
          are willing to pay yet not receive.
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System