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: [email protected]
[127.0.0.1] didn't use HELO protocol
> To: "Mark Rivers" <[email protected]>
> cc: <[email protected]>
> Subject: Re: aiRecord, RVAL vs. VAL
> Date: Thu, 04 Dec 2003 17:42:35 -0500
> From: "Brian McAllister" <[email protected]>
> 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
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