Experimental Physics and
Industrial Control System

At first glance, EPICS for a small control system seemed like using a cannon to get my goldfish out of the bowl.  But with some years of experience, I have come to appreciate the side benefits of this system.

One of the benefits was demonstrated with a visitor to the lab's periodic open house.  He wanted to have better temperature control of his home brewing (yes, beer) process, to avoid overshoot.  Was using a RPi-based control system with sufficient additional sensors and other controls, just wanted better control of the temperature profile with time (controlled ramp up, hold, controlled cool down, ...).  "Wow!  Sounds like you want PID control.  Rather than invent and implement more of this in your custom protocols, why not use EPICS and the epid record?"  With this, Ryan controlled the temperature overshoot in the process. He described the process at an EPICS collaboration meeting.  For more details, see https://epics.anl.gov/meetings/2018-06/RyanPierce_Chi.html and https://oomlout.co.uk/blogs/news/82204993-ryan-pierces-cnc-beer-brewing-station-project.html

I'd recommend using EPICS, even on a small scale because the implementation is not difficult and the side benefits can be surprising.

Pete


On 8/18/2022 2:09 PM, Sean Leavey - STFC UKRI via Tech-talk wrote:

Hi Michael,

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

Good to know it can work on that scale!

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.

Indeed, I guess I was hoping someone else had already done what you say, started with 20 lines of Python and fixed the edge cases you mention, without it becoming a behemoth. But you've convinced me to give Archiver Appliance a go with what you said about the Pis!

Cheers,
Sean
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--
----------------------------------------------------------
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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References:

EPICS for a small lab - overkill? Sean Leavey - STFC UKRI via Tech-talk

Re: EPICS for a small lab - overkill? Arnold, Ned D. via Tech-talk

Re: EPICS for a small lab - overkill? Sean Leavey - STFC UKRI via Tech-talk

Re: EPICS for a small lab - overkill? Michael Davidsaver via Tech-talk

Re: EPICS for a small lab - overkill? Sean Leavey - STFC UKRI via Tech-talk

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