Argonne National Laboratory

Experimental Physics and
Industrial Control System

1994  1995  1996  1997  1998  1999  2000  2001  2002  <20032004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  Index 1994  1995  1996  1997  1998  1999  2000  2001  2002  <20032004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019 
<== Date ==> <== Thread ==>

Subject: Re: aiRecord, RVAL vs. VAL
From: Allan Honey <ahoney@keck.hawaii.edu>
To: rivers@cars.uchicago.edu, brian@hotrats.mit.edu
Cc: tech-talk@aps.anl.gov
Date: Thu, 4 Dec 2003 14:52:36 -1000 (HST)
In a more recent update to devAscii, the returned value is written
directly into the record's VAL field, thereby bypassing the RVAL/ESLO 
conversions. To do this the device support must also return the
"don't convert" status. This may be a better solution if you are
creating a device specific support layer.

AH


> X-Authentication-Warning: hotrats.mit.edu: brian@localhost.localdomain 
[127.0.0.1] didn't use HELO protocol
> To: "Mark Rivers" <rivers@cars.uchicago.edu>
> cc: <tech-talk@aps.anl.gov>
> Subject: Re: aiRecord, RVAL vs. VAL 
> Date: Thu, 04 Dec 2003 17:42:35 -0500
> From: "Brian McAllister" <brian@hotrats.mit.edu>
> X-Mts: smtp
> List-Help: <http://www.aps.anl.gov/epics/tech-talk/index.php>
> 
> 
> >>> On 12/4/2003 at 16:30:38 CST, Mark Rivers wrote:
> 
>   > I agree that having the RAW field be an integer is a limitation.  For
>   > example, I might want to read a voltage from a digital multimeter,
>   > which returns a floating point number, but then have that number
>   > converted to some other units, for example pressure, by the ai record
>   > conversion routine.  As it stands I think device support would have to
>   > do that conversion directly, it could not write into the RVAL field and
>   > ask the record to do the conversion.
> 
> One work-around for this (which is used by devAscii, for instance) is to
> scale the value read from the device up in the device support so that it
> can be represented as an integer while maintaining useful precision, and
> then to scale it back down in the conversion to your desired units.
> 
> - brian


Navigate by Date:
Prev: Re: aiRecord, RVAL vs. VAL Brian McAllister
Next: Novice EPICS questions re yet another port David Kelly
Index: 1994  1995  1996  1997  1998  1999  2000  2001  2002  <20032004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019 
Navigate by Thread:
Prev: Re: aiRecord, RVAL vs. VAL Brian McAllister
Next: Novice EPICS questions re yet another port David Kelly
Index: 1994  1995  1996  1997  1998  1999  2000  2001  2002  <20032004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019 
ANJ, 10 Aug 2010 Valid HTML 4.01! · Home · News · About · Base · Modules · Extensions · Distributions · Download ·
· Search · EPICS V4 · IRMIS · Talk · Bugs · Documents · Links · Licensing ·