Re: [EXTERNAL] Does every DB record need to produce a PV?

["Hartman, Steven via Tech-talk" <tech-talk at aps.anl.gov>]

What makes you think this is unmanageable? There are plenty of counter examples of existing facilities where this works.

-- 

Steven Hartman

hartmansm at ornl.gov

On Feb 17, 2026, at 12:12 PM, Sukhanov, Andrei via Tech-talk <tech-talk at aps.anl.gov> wrote:

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Mark, Kai,
The multitude of the PVs, not related to real device parameters, may pose real trouble for end users. For example, we were provided with an EPICS-driven PSC (power supply controller). The controller itself has ~200 of control parameters. But the IOC hosts ~2000 of PVS. This is just not manageable without tight support from original designers.

/Andrey Sukhanov,

Collider-Accelerator Department, BNL.

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From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Mark Rivers via Tech-talk <tech-talk at aps.anl.gov>
Sent: Tuesday, February 17, 2026 11:54 AM
To: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>; David Bracey <dbracey at fnal.gov>
Subject: Re: Does every DB record need to produce a PV?

 

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Hi Dave,

• A naïve user of EPICS would think that every database record of every IOC gets exposed as a PV.

Note that there is not a 1:1 relationship between records and PVs.  Even simple records like "bi" expose many record fields as PVs, not just the .VAL field.  For example, the .SCAN, .ZNAM, .ONAM, .SDIS, .DESC, and many more.  More complex records like the "motor" record have dozens of PVs, like .VELO, .ACCL, .STOP, .DVAL, .RVAL, etc.

Mark

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From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of David Bracey via Tech-talk <tech-talk at aps.anl.gov>
Sent: Monday, February 16, 2026 10:15 AM
To: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: Does every DB record need to produce a PV?

 

A naïve user of EPICS would think that every database record of every IOC gets exposed as a PV.

 

Is this truly the case?  If so, has any mechanism for hiding the “internal” records ever been discussed?

 

The PV-space of an EPICS deployment seems very crowded.

 

Dave Bracey

AD Controls

Fermi National Accelerator Laboratory