Experimental Physics and
Industrial Control System

"Loeher, Bastian Dr. via Tech-talk" <tech-talk at aps.anl.gov> · Wed, 15 Mar 2023 17:11:41 +0000

Dear Greg,

I can say a few words about how we operate at NUSTAR/GSI:

We are mainly using EPICS to control and monitor our equipment, but not for high-speed data acquisition from experiment detectors. We refer to EPICS as the 'slow control' system.

How many data points do you collect?

We collect data from the controlled devices, and the amount of data points (both in amount and collection/scan frequency) depends a lot on the particular device. Most of the collected data is only used for the momentary display and not stored permanently.

How fast do you collect data?

Most data points are collected on the basis of 1 second or 10 seconds. Only very few variables are scanned with higher frequency.

Do you archive every data point you collect?

No. We keep (auto-generate) a list of process variables that are used for the archiver. Most process variables are not useful for archiving, i.e. have no use in data analysis.

Do you archive data slower than you collect it?

That depends. Some process variables have archiver deadbands defined differently from the monitor deadband. In most cases the collection frequency is low enough that we can easily archive all changes.

What are you using to archive data?

We've got a custom archiver (epics_collector) that has an interface to an InfluxDB database. The collector is mainly a CA client that runs in a loop and tracks and forwards changes to a variety of backends (such as the Influx DB database).

How many IOCs do you have?

100 < x < 500. I don't know the exact number.

New IOC vs. an existing one?

We try to keep one IOC tied to a particular device. So, each of our experiment detectors would usually have a number of IOCs associated with different parts of the detector. We also have a second higher-level layer of IOCs controlling/monitoring all IOCs associated with one detector. These IOCs do not control any hardware directly, but only interact with the IOCs one level down.

If you have more questions, please don't hesitate to ask.

All the best
Bastian
________________________________________
Von: Tech-talk <tech-talk-bounces at aps.anl.gov> im Auftrag von Leblanc, Gregory via Tech-talk <tech-talk at aps.anl.gov>
Gesendet: Dienstag, 14. März 2023 22:10:51
An: tech-talk at aps.anl.gov
Betreff: How is EPICS used at your facility?

How do you use EPICS at your facility?  We aren't using it yet and I am trying to make some design decisions before I get very far down the implementation road.  The thread last week about SCAN issues and the archiver appliance brought some of these to mind.

How many data points do you collect?
How fast do you collect data?
Do you archive every datapoint you collect?
Do you archive data slower than you collect it?
What are you using to archive data (EPICS Archiver Appliance, CSS, Phoebus, other?)?
How many IOCs do you have, and how do you decide when you need a new IOC vs extending an existing IOC?
What do you use for visualization (CSS, Phoebus, custom solution (based on qtepics?), something else)?

I'm sure I could come up with a dozen more questions about how EPICS is implemented, but maybe another time.
    Greg

P.S. If there's interest in collecting any of this data I could put together a survey and make the data available (Ohio has some decent survey data collection tools).

--
Gregory Leblanc
Accelerator Engineer
Edwards Accelerator Lab - Ohio University
123 University Terrace
Athens, OH 45701 USA
leblanc at ohio.edu
M: (401) 52-OUAL1 or (401) 526-8251

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System