Experimental Physics and
Industrial Control System

Marty Kraimer <[email protected]> · Tue, 24 Jul 2001 09:12:34 -0500

"Redman, Russell O." wrote:
> 
> On Friday, July 20, 2001 11:53 AM, Marty Kraimer [mailto:[email protected]]
> sent
> 
> > EOFF and ESLO cant be computed by softRaw support
> >
> > Russell Redman suggests that we add fields RAWL and RAWF.
> > Instead of this why dont we just allow the user to assign values
> > to ESLO and EOFF, i.e. just add promptgroup definitions to the dbd files.
> 
> I do not really want to add new fields, but my logic is as follows:
> 
> 1) We do not need to assign values to EOFF and ESLO because the same
> functionality is already available through the AOFF and ASLO fields.
> 
> 2) The ranges of the raw and engineering units are both normally simple
> numbers, easily understood by engineers and programmers.  For instance, the
> voltage range [0.0, 5.0] volts may transform to raw counts [0, 4095].  The
> slope, however is an awkward quantity ESLO=(EGUH-EGUL)/(RAWH-RAWL) =
> 5.0/4095 = 1.21001221001221e-3.
> 
> (Oops, I made a typo in that slope.  How many of you caught it just looking
> at the number?)
> 
> EPICS applications will be more maintainable if the fields contain values
> that are simple and physically meaningful.

OK I am willing to add RAWF and RAWL. Unless I hear objections this will appear
in the next releases of both 3.13 and 3.14.
I will add the fields to aiRecord and aoRecord. I will also modify 
devAiSoftRaw.c and devAoSoftRaw.c.

Note that the names will be (RAWF,RAWL) not (RAWH,RAWL). This is similar to the
names (EGUF,EGUL). Perhaps (EGUH,EGUL) are better names but it is way to late to
make such a change.

> Just out of curiosity, is there a reason why the variable "value" in convert
> is set to 0.0 when LINR==LINEAR and ESLO==0.0, instead of just being left
> alone?

This is in aoRecord.c

No good reason. But if eslo is 0.0 then it probably means that something is not
configured correctly or else the attached device support is not written
correctly.

Marty Kraimer

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System