Re: Listen to multiple events

[Korhonen Timo <Timo.Korhonen@psi.ch>]

Emmanuel Mayssat wrote:
> On Tue, 2008-03-18 at 13:09 +0100, Korhonen Timo wrote:
>   
> > set to the same number. The ai record could then look like this:
> >
> > record(ai, "Test:RecordToProcessOnEvent1or2") {
> >   field(SCAN, "Event")
> >   field(EVNT, "1")   
> > #EVNT is the soft event number
> >
> > ...other ai fields here...
> > }
> >     
>
> The problem with this method is that you have to keep track of the event
> numbers in use. I believe epics support only 256 events. If a device
> driver sends the same event ~number~ than the one expected by another
> driver, then you are toasted!
>
>   
Well, there is no free lunch ;-)
However, it is anyway a good idea to keep track of the events
and (IMHO) a small price to pay for the flexibility you get with that 
method.
The 'soft' event numbers need only to be unique per IOC. Hard coding the 
event
number in a driver would not be a very good idea. Usually this is done 
in the record level
(like the event or calcout records) so the numbers can be managed by the 
app developer
in the record configuration.

As Stephanie pointed out, this discussion was specific to event 
receivers, but of course
nothing stops one from implementing a similar method for other hardware.

best regards,

Timo


--
Timo Korhonen  PSI (Paul Scherrer Institut, http://www.psi.ch) 
              CH-5232 Villigen PSI 
              tel + 41- 56 3103262  fax + 41 - 56 310 3383 
e-mail:	       timo.korhonen@psi.ch