RE: another question on custom record stuff

["Jeff Hill" <johill@lanl.gov>]

> Now the problem is that if I change the limit field then well.
> MEDM just doesn't know about it.
> So how do I get that part to run again?
> Or is this another one of those impossible things :(

Unfortunately, it's not currently possible for MEDM, or any other EPICS
client, to subscribe for updates to be sent when there are changes in the
limits. Therefore, most clients fetch the limits when they connect and
assume that they don't change after that. Perhaps that might explain EDM's
behavior.

Note that MEDM will update its limits if its forced to reconnect.

PS: This could be fixed in the database by creating a new subscription
trigger option bit (in addition to DBE_VALUE, DBE_LOG, and DBE_ALARM). In
the current system the limit changes wouldn't be stored on the event queue,
but notification would be, and a current value would be fetched by the
server when sending the subscription update message, and that would probably
be a fully suitable behavior considering that limits don't change very
often. Nevertheless, changes are coming in R3.15 which will allow almost any
data structure to be potentially stored on the event queue (including the
limits).

Jeff

> -----Original Message-----
> From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-
> bounces@aps.anl.gov] On Behalf Of Heinrich du Toit
> Sent: Thursday, October 25, 2007 5:37 AM
> To: TechTalk EPICS
> Subject: another question on custom record stuff
> 
> I have a field that is an array
> And with that field I have the get_graphic_double routine that gives
> out
> the limits for that array.
> 
> Now I have another field that is actually the limit.
> So the get_graphic_double routine simply puts that field inside
> upper_disp_limit
> And it work well the first time.
> 
> Now the problem is that if I change the limit field then well.
> MEDM just doesn't know about it.
> So how do I get that part to run again?
> Or is this another one of those impossible things :(