Experimental Physics and
Industrial Control System

Michael Davidsaver via Tech-talk <tech-talk at aps.anl.gov> · Thu, 18 Aug 2022 12:07:42 -0700

On 8/18/22 10:59, Maren Purves wrote:

Question: if you're running softIocs anyway, is there a good reason to
not run them on something you already have?

There is no technical restriction.  I've set up test stands with
everything (IOCs, archiver, and UI) on one old desktop tower.
I can be a natural starting point when it isn't clear how
a test stand will be utilized.

Given the opportunity, the first separation I like to make is
between UIs and non-interactive tasks.  I've found that users can
be very effective at conducting unplanned stress testing.

I'm running e.g. alarm
handlers with the X interface on a virtual desktop on the machine that
has the channel archiver on it after having them run on my own desktop
for a while. When I was trying to get a softIoc running I just put it
on my desktop for testing.

TIA,
Maren

On Thu, Aug 18, 2022 at 7:51 AM Feister, Scott via Tech-talk
<tech-talk at aps.anl.gov> wrote:

Hi everyone!

Sorry to jump in at the last minute here on this thread, but I'm working on a similar "EPICS for a small lab" project and would be glad to share notes with anyone else interested.

Here's the documentation for the system we're building using Raspberry Pis (and/or Beaglebone PCs) and Arduinos.

https://sfeister.github.io/sidekick-epics-docs/sidekick-overview/

Feel free to reach out to me directly if you'd like to discuss more!

-Scott

-----Original Message-----
From: Tech-talk <tech-talk-bounces at aps.anl.gov> On Behalf Of Michael Davidsaver via Tech-talk
Sent: Thursday, August 18, 2022 9:16 AM
To: Sean Leavey - STFC UKRI <Sean.Leavey at stfc.ac.uk>
Cc: tech-talk at aps.anl.gov
Subject: Re: EPICS for a small lab - overkill?

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On 8/17/22 12:47, Sean Leavey - STFC UKRI via Tech-talk wrote:

Sounds reasonable to me!

Great. Do you have any recommendations on how the single box should be set up? I saw some Docker images but not sure it's worth the effort over just building from source manually. I'd probably opt for Debian because that's what I know best. I'd put the IOC on the same box as the base, and use the Modbus support that I think is baked in already.

Archival is something I wanted to ask more about. It doesn't look like a good idea to use Archiver Appliance. Is there a lightweight archiver for a handful of channels (say up to 20) at 1 Hz or less? I could probably write one in 20 lines of Python (camonitor some channels, write values to a text file every N seconds, rotate file once per day), but I hope there's one that also supports data access, e.g. retrieving data between certain times via some network request... wishful thinking?

fyi.  Archiver Appliance can be scaled down.  I have AA running on a raspberry pi 3 in my apartment recording ~10 PVs.

The only adjustment I have to make made for this little rpi is to reduce the JVM memory limit ("-Xmx128M").  Which works just fine for such a small setup.

wrt. "I could probably write one in 20 lines of ..."

I'm sure you could, and many have.  As with most software, getting a 90% solution is easy.  The trouble is that last 10% consists of things which aren't apparent.  eg. recording disconnect/reconnect, data type change, and various problems with timestamps.  Events which can, and imo. eventually will, turn up in every installation no matter the size.

While there were, and are, a number of special purpose, and/or site specific archivers.  AA is one of a small number (I think 3) which are flexible and robust enough to gain widespread adoption.  Of these, AA is the only one currently recommended by its author for new installs.

________________________________________
From: Arnold, Ned D. <nda at anl.gov>
Sent: 17 August 2022 20:41
To: tech-talk at aps.anl.gov; Leavey, Sean (STFC,ROE,UKATC)
Subject: Re: EPICS for a small lab - overkill?

Has anyone used EPICS on such a small scale? Was it more trouble than it was worth compared to turnkey commercial solutions?

We use it in the labs and for small test stands all the time ... and those are much easier to manage than the large deployments ... you don't have to manage 100's of IOCs, hundreds of thousands of process variables, data archiving does not require a large "archiver" etc, etc, etc.  The size of the system greatly increases the maintenance overhead.

It also sounds like your I/O could be accomplished with Ethernet-based I/O with the IOC running whereever convenient.

Sounds reasonable to me!

    Ned

________________________________
From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Sean
Leavey - STFC UKRI via Tech-talk <tech-talk at aps.anl.gov>
Sent: Wednesday, August 17, 2022 02:26 PM
To: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: EPICS for a small lab - overkill?

Hi all,

I'm trying to determine the feasibility of using EPICS for simple monitoring of a small clean room facility. We'll need to read out various sensors (particle counters, temperature, etc.) via Modbus over Ethernet and archive the data at low speed (a few times per minute maybe) and also ideally display live data to lab users on a GUI (e.g. MEDM or modern equivalents). We're probably going to have a small number of outputs as well: automated switching of lights, fans, motors, that kind of thing. Maybe some alarms for e.g. triggering a warning light if particle counts get too high. No closed loops.

We could probably just use LabVIEW or similar but I don't like it much and prefer a licence-free and open source solution that can be easily adapted as needed. Plus, I may clone the EPICS setup to a different lab in a different city that we work with, so it would be nice to be able to use a gateway to access and archive their channels as well.

Has anyone used EPICS on such a small scale? Was it more trouble than it was worth compared to turnkey commercial solutions?

Any input would be appreciated!
Sean Leavey
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System