RE: lexical analyzer for .db?

["Owens, PH \(Peter\)" <p.h.owens@dl.ac.uk>]

If you were going to do it that way you could use the PHAS
field to ensure that the calc records were processed later
in the scan than the inputs - thus processed up-to-date values.


> -----Original Message-----
> From: tech-talk-bounces@aps.anl.gov
> [mailto:tech-talk-bounces@aps.anl.gov]On Behalf Of Heinrich du Toit
> Sent: 02 November 2007 14:02
> To: Eric Norum; EPICS tech-talk
> Subject: Re: lexical analyzer for .db?
> 
> 
> Hi
> 
> Thanks for all your help
> 
> Wonder why the FLNK isn't a direct DB link then if possible? (e.g. 
> record inside same IOC)
> Does the fanout do it differently?
> 
> What would you say about the idea of just putting all the 
> inputs on SCAN 
> = .2 second
> and then all the calc(out) rule records also on .2seconds SCAN ?
> 
> The way I see it a calc record can then never work with a value older 
> than .4 seconds... which is fine for the system I think.
> 
> Can maybe just FLNK or fanout the critical stuff then
> 
> -H
> 
> 
> Eric Norum wrote:
> > On Nov 2, 2007, at 8:30 AM, Ned Arnold wrote:
> >
> >>
> >> You may be able to eliminate the fanout records by careful 
> design of 
> >> forward links and/or input link flags (PP, CP, etc).
> >>
> >> For example, if the input record's forward link field 
> referenced the 
> >> calc record and the calc record's forward link field 
> referenced the 
> >> calcout record, all would process each time the input record 
> >> processed ... without a fanout.
> >>
> >
> > Don't take this technique to extremes, though.  I recall 
> helping Steve 
> > Shoaf diagnose problems with his database for a video switching 
> > system.  The database contained 128 records FLNK'd together.  This 
> > caused very weird IOC faults that we finally realized were 
> caused by 
> > stack overflow of the task processing the records -- 128 recursive 
> > calls to the record processing routine forced the task 
> stack pointer 
> > past the end of the stack space.
> > --Eric Norum <norume@aps.anl.gov>
> > Advanced Photon Source
> > Argonne National Laboratory
> > (630) 252-4793
> >
> >
> 
>