Experimental Physics and
Industrial Control System

Hinko Kocevar via Tech-talk <[email protected]> · Sat, 25 May 2019 15:35:56 +0000

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 <[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

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System