EPICS Controls Argonne National Laboratory

Experimental Physics and
Industrial Control System

1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  <20142015  2016  2017  2018  2019  2020  2021  2022  2023  2024  Index 1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  <20142015  2016  2017  2018  2019  2020  2021  2022  2023  2024 
<== Date ==> <== Thread ==>

Subject: Re: EPICS alarming on VAL != X
From: Andrew Johnson <[email protected]>
To: <[email protected]>
Date: Fri, 25 Jul 2014 10:31:57 -0500
On 07/25/2014 07:05 AM, Benjamin Franksen wrote:
> On Thursday 24 July 2014 11:27:24 Andrew Johnson wrote:
>> If
>> you want to stop changes for a while, disable record processing using
>> SDIS & DISV.
> 
> I don't think this will prevent the VAL from changing e.g. due to put
> operations, or does it?

Ahh, for that you also have to set DISP (which I was thinking about when
I wrote that but forgot to mention).

On 07/25/2014 07:34 AM, Dirk Zimoch wrote:
> Does it make sense to change the code to:
>
> if (prec->drvh >= prec->drvl)
>
> And change the default values so that DRVL>DRVH (e.g. DRVL=0, DRVH=-1)
>
> Then nothing would change if the db designer ignores the fields.

But a database that dynamically switches the limits on & off by writing
to DRVL and/or DRVH (depending on machine mode say) could break.

On 07/25/2014 08:58 AM, Benjamin Franksen wrote:
> On Friday 25 July 2014 14:34:13 Dirk Zimoch wrote:
>> Another alternative is to set default values DRVL=-Inf and DRVH=Inf.
>
> I like this idea. It precisely captures the desired default behaviour
> w/o imposing any artificial limitation. I guess the 'if (prec->drvh >
> prec->drvl)' hack was from before +/-Inf was standardized.

I still think there may be databases out there that rely on being able
to set DRVH and DRVL to the same value to disable the limit checks.
Changing the DRVH > DRVL test to DRVH >= DRVL will break those IOC
databases.

> BTW, does dbLoadRecords understand +/-Inf in a db file? Does
> dbLoadDatabase in a record type field definition's "initial" property?

I believe so, it worked from dbLoadRecords when I tried it on Linux just
now. However it's more efficient to avoid doing the individual value
checks at all by defaulting DRHV to DRVL.

- Andrew
-- 
Advertising may be described as the science of arresting the human
intelligence long enough to get money from it. -- Stephen Leacock

References:
EPICS alarming on VAL != X Jameson Graef Rollins
Re: EPICS alarming on VAL != X Benjamin Franksen
Re: EPICS alarming on VAL != X Andrew Johnson
Re: EPICS alarming on VAL != X Benjamin Franksen

Navigate by Date:
Prev: Re: EPICS alarming on VAL != X Benjamin Franksen
Next: can't see epicsqt widgets in QT designer Hansen
Index: 1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  <20142015  2016  2017  2018  2019  2020  2021  2022  2023  2024 
Navigate by Thread:
Prev: Re: EPICS alarming on VAL != X Benjamin Franksen
Next: Re: EPICS alarming on VAL != X Jameson Graef Rollins
Index: 1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  <20142015  2016  2017  2018  2019  2020  2021  2022  2023  2024 
ANJ, 17 Dec 2015 Valid HTML 4.01! · Home · News · About · Base · Modules · Extensions · Distributions · Download ·
· Search · EPICS V4 · IRMIS · Talk · Bugs · Documents · Links · Licensing ·