Experimental Physics and
Industrial Control System

"tom.cobb--- via Tech-talk" <[email protected]> · Mon, 3 Jun 2019 09:31:50 +0000

Hi Hinko,

You may already have this covered with ethercat, but if you need some hardware that will average encoders and/or ADC value over possibly uneven hardware gates you can do this with PandABox:

https://www.ohwr.org/project/pandabox/wikis/home

For orchestrating hardware together to perform a hardware synchronized scan, Diamond has taken a different approach to Bluesky. We provide a Python middlelayer scanning service (Malcolm) that configures and supervises the underlying devices via CA, then exposes a higher level PVA interface up that the UI can use. This is because we already have a user facing application http://www.opengda.org/ so we needed a service that could provide hardware triggered scanning, rather than a top level application that could be given to end users.

Paper: http://accelconf.web.cern.ch/AccelConf/icalepcs2017/papers/tupha159.pdf
Docs: https://pymalcolm.readthedocs.io/en/latest/
Repo: https://github.com/dls-controls/pymalcolm

Thanks,
Tom

> -----Original Message-----
> From: [email protected] <[email protected]> On
> Behalf Of Hinko Kocevar via Tech-talk
> Sent: 25 May 2019 16:36
> To: Mark Rivers <[email protected]>
> Cc: [email protected]
> Subject: Re: Scanning 101
> 
> Mark, regarding the timing, I'm working with MRF EVG/EVR timing system.
> I'm mostly looking at uTCA AMC or IPC PCI based cards.
> As you probably know, one would use mrfioc2 to configure EVR to produce
> triggers on a backplane or frontpanel upon receiving an event from EVG.
> In addition, EVR can keep track of (absolute) time to be used to timestamp
> records of choice (through TSEL field).
> The machine repetition rate is 14Hz, and I would like to have relevant PVs all
> be timestamped at that precision.
> The (soft) IOC runs on Linux based OS, and it could potentially incorporate all
> the support modules needed for scanning (DAQ, motion, timing,..).
> 
> Torsten, motion controller in my case is from ESS MCAG, ecmc based,
> AFAICT. I would need to more insight into the motor control and how it could
> be coupled with scanning application, though. Will contact you offline for
> some guidance, if I may, especially in regard to EVR timestamping.
> I would like to stick to the EPICS records to perform scanning, and not rely on
> other codes and/or programing languages. I can not tell if this (self-imposed)
> restrictions are getting me the furthest, though.
> 
> To elaborate, my /simplest/ use case is:
>  * single axis motor control, w/ encoder readout and limit switch handling
> based on Ethercat (ESS ecmc)
>  * single DAQ channel
>  * EVR triggered DAQ
>  * EVR timestamped (cherry picked) PV
>  * optionally control other units (HV bias,..)
> 
> I want to:
> * move the motor in position (let is settle?),
> * check limit switches,
> * read encoder values,
> * acquire several waveforms (optionally perform waveform averaging / ROI /
> other processing to produce a single value),
> * timestamp my favorite PVs,
> * archive (using Archiver Aappliance or HDF5 file or ??) all my favorite PVs,
> * .. repeat the above steps n-times
> 
> The ultimate goal is to be able to retrieve the archived PVs and correlate
> them using the timestamp in order to reconstruct the measurement/scan.
> 
> Will look into sscan module docs.
> 
> Would one use EPICS sequencer for any reason with scanning?
> Is there a minimalistic (dummy) IOC to be studied that does scanning?
> 
> Thanks!
> //hinko
> ________________________________________
> From: Mark Rivers <[email protected]>
> Sent: Thursday, May 23, 2019 12:37:32 PM
> To: Hinko Kocevar
> Cc: [email protected]
> Subject: Re: Scanning 101
> 
> Hi Hinko,
> 
> My first response would be to use the sscan record. But I need more
> explanation of what you mean by "timing system with precision triggering
> and timestamping".
> 
> Mark
> 
> 
> Sent from my iPhone
> 
> > On May 23, 2019, at 4:12 AM, Hinko Kocevar via Tech-talk <tech-
> [email protected]> wrote:
> >
> > Imagine an EPICS developer with no experience in working with
> (coordinated) scanning application.
> >
> > The sub-units, of the system in need of scanning feature, include timing
> system with precision triggering and timestamping, 1 to several axes of
> motion, control of HV bias and 1 to several channels of data acquisition. You
> can assume that the (low-level) EPICS modules supporting the hardware are
> under my control already, I'm interested in orchestrating the scan using
> above constituents.
> >
> > What would be preferred approach to tackle this subject with EPICS in
> 2019?
> >
> > TIA,
> > Hinko

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System