Experimental Physics and
Industrial Control System

Benjamin Franksen <[email protected]> · Tue, 14 Aug 2001 21:23:20 +0200

Andrew Johnson wrote:
> 
> Marty Kraimer wrote:
> >
> > Benjamin Franksen wrote:
> > >
> > > Does this mean that ESLO and EOFF will be made configurable?
> >
> > I will add promptgroup(GUI_CONVERT) to both.
> > Question. What should special be?
> > It is currently defined as special(SPC_NOMOD). The question becomes. Should this
> > field be dynamically configurable. If we remove special(SPC_NOMOD) should we
> > define asl(ASL0)?
> 
> Acording to the source for aiRecord.c, EOFF gets set to the value of EGUL
> at init time and every time a special(SPC_LINCONV) field is changed
> (before calling the dset->special_linconv() routine which may change it
> again), so the above makes no sense for EOFF.  The ESLO field is only set
> by device support, but if this field is made configurable then designers
> will set it when they don't need to, and then be surprised when their
> value is overwritten by any hardware device support at iocInit or when any
> special(SPC_LINCONV) field is modified.  This modification is not posted
> as a CA monitor, and this could cause confusion if we make ESLO
> modifyable.
> 
> [...more justified reasons not to make ESLO and EOFF configurable...]

With my new proposal this problem could be solved, since in this case
LINR field will no longer have value LINEAR (but LINEAR_MANUAL or
whatever better name we agree on).

There are two possibilities:

(1) Assume (and demand!) that device supports check the LINR field to
see if it is LINEAR before they set ESLO and EOFF. I believe most of
them do. Add the check to the remaining ones.

(2) Forget the idea that device support sets EGUL and EGUF (instead of
ESLO and EOFF) if LINR==LINEAR_MANUAL. Call dset->special_linconv() only
in case LINR==LINEAR.

Ben
-- 
Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung
(BESSY) GmbH, Control System Group
Albert-Einstein-Straße 15, 12489 Berlin, +4930 6392 8462, www.bessy.de

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System