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<== Date ==> <== Thread ==>

Subject: RE: DB Question
From: "Szalata, Zenon M." <zms@slac.stanford.edu>
To: "nick.rees@diamond.ac.uk" <nick.rees@diamond.ac.uk>, "rivers@cars.uchicago.edu" <rivers@cars.uchicago.edu>, "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
Date: Fri, 16 Nov 2012 09:37:44 -0800
Thanks,
This is an interesting way to solve it.  I will test it.
Zen

> -----Original Message-----
> From: nick.rees@diamond.ac.uk [mailto:nick.rees@diamond.ac.uk]
> Sent: Friday, November 16, 2012 9:23 AM
> To: rivers@cars.uchicago.edu; Szalata, Zenon M.; tech-talk@aps.anl.gov
> Subject: RE: DB Question
> 
> IIRC (I don't have the code in front of me at the moment) the way to override
> this asyn behavior is to set OMSL to Closed Loop and DOL to a constant value.
> 
> Cheers,
> 
> Nick Rees
> Principal Software Engineer           Phone: +44 (0)1235-778430
> Diamond Light Source                  Fax:   +44 (0)1235-446713
> 
> Mark Rivers <rivers@cars.uchicago.edu> wrote:
> Hi Zen,
> 
> Remember that standard asyn device support for output records does the
> following at iocInit:
> 
> 
> 1)      Attempts to read the current value from the asyn port driver
> 
> 2)      If that read returns asynSuccess then the VAL field in the record is
> replaced by the one read from the driver
> 
> 3)      If that return does not return asynSuccess then the VAL field is not
> modified
> 
> This behavior is designed to support "bumpless reboots".
> 
> I suspect your driver is returning asynSuccess on a call to asynInt32->read() at
> iocInit.  If you want to preserve the value of the VAL field from the database file
> then your driver must not return asynSuccess.
> 
> Mark
> 
> 
> From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov]
> On Behalf Of Szalata, Zenon M.
> Sent: Friday, November 16, 2012 10:32 AM
> To: tech-talk@aps.anl.gov
> Subject: DB Question
> 
> Hi,
> I am a bit confused by the following behavior.
> I am using EPICS R3.14.12.2 and asyn R4.20.
> I have a simple longout record:
> 
> record( longout, "$(P):$(N):LO:BTOI:NCOEF"){
>   field( DESC, "N Coefs:")
>   field( DTYP, "asynInt32")
>   field( OUT,  "@asyn($(PORT),$(N),1)LO_NCOEF")  field( VAL,  "2")
>   field( PINI, "1")
> }
> 
> After this record is done initializing, caget on it gives me 0.
> 
> I have introduced another record as follows:
> 
> record( longout, "$(P):$(N):LO:NCOEF"){
>   field( DESC, "N Coefs:")
>   field( VAL,  "2")
>   field( OUT,  "$(P):$(N):LO:BTOI:NCOEF PP")
>   field( PINI, "1")
> }
> record( longout, "$(P):$(N):LO:BTOI:NCOEF"){
>   field( DESC, "N Coefs:")
>   field( DTYP, "asynInt32")
>   field( OUT,  "@asyn($(PORT),$(N),1)LO_NCOEF") # field( VAL,  "2") #  field(
> PINI, "1") }
> 
> With these two records the second one now has the correct value.
> Why does the single record solution lose its VAL value?
> 
> Thanks in advance,
> Zen
> 
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References:
DB Question Szalata, Zenon M.
RE: DB Question Mark Rivers
RE: DB Question nick.rees

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