Experimental Physics and
Industrial Control System

"Jeff Hill" <[email protected]> · Thu, 15 Dec 2005 09:18:01 -0700

> But can I get the value of VAL field when camonitor RVAL field?
> I want to get the value of VAL & RVAL field when camonitor one field.
> DBR_TIME_XXXX just return the value of specified field.

As Andrei has mentioned it is of course possible to set up two subscriptions
(one for VAL and one for RVAL), but that appears to not be what you are
after.

It isn’t easy to receive both VAL and RVAL as an atomically packaged
subscription update with the current versions of EPICS. One possibility
would be to create a waveform record with two elements. You might arrange to
atomically copy the ai's VAL and RVAL fields into the waveform record's two
elements. You might then monitor the waveform record, and receive the two
elements atomically with each subscription update. Admittedly, that is a
somewhat contrived solution.

The Data Access library that Ralph Lange and I have been working on
facilitates flexible packaging Channel Access data. It is designed to
seamlessly eliminate limitations of this type.

Jeff

> -----Original Message-----
> From: huangsong [mailto:[email protected]]
> Sent: Wednesday, December 14, 2005 6:10 PM
> To: Jeff Hill
> Cc: [email protected]
> Subject: Re: about CA monitor
>
> Hello, Jeff Hill
>
> But can I get the value of VAL field when camonitor RVAL field?
> I want to get the value of VAL & RVAL field when camonitor one field.
> DBR_TIME_XXXX just return the value of specified field.
>
>
> On Wed, 14 Dec 2005 10:52:13 -0700
> "Jeff Hill" <[email protected]> wrote:
>
> >
> > Hello Huang, Song;
> >
> > > I use Channel Access Monitor function to monitor a PV (VAL field).
> > > When event triggered, it returns the value of VAL field, timestamp,
> alarm
> > > status and other things.
> > > But I also want to get the value of other fields (e.g. RVAL) when
> event
> > > triggered.
> > > In db_Access.h, it seems all types can't do this.
> > >
> > > Do I have to get the value of other fields in Event Handler?
> >
> > One possibility would be to set up a subscription using type
> DBR_TIME_XXXX
> > on channel "<record name>.<field>" expecting to receive the value of the
> > specified field along with the time stamp and the alarm status of the
> record
> > with each subscription update.
> >
> > For example we can test this as follows:
> >
> > > camonitor aiExample.RVAL
> > aiExample.RVAL        2005-12-14 10:42:25.992078 0 LOLO MAJOR
> > aiExample.RVAL        2005-12-14 10:43:23.994643 3 LOW MINOR
> > aiExample.RVAL        2005-12-14 10:43:24.994700 3
> > aiExample.RVAL        2005-12-14 10:44:04.996487 4
> > aiExample.RVAL        2005-12-14 10:44:05.996576 4 HIGH MINOR
> >
> > All the best,
> >
> > Jeff
> >
> > > -----Original Message-----
> > > From: huangsong [mailto:[email protected]]
> > > Sent: Wednesday, December 14, 2005 1:46 AM
> > > To: [email protected]
> > > Subject: about CA monitor
> > >
> > > Hello,
> > >
> > > I use Channel Access Monitor function to monitor a PV (VAL field).
> > > When event triggered, it returns the value of VAL field, timestamp,
> alarm
> > > status and other things.
> > > But I also want to get the value of other fields (e.g. RVAL) when
> event
> > > triggered.
> > > In db_Access.h, it seems all types can't do this.
> > >
> > > Do I have to get the value of other fields in Event Handler?
> > >
> > >
> > > Best wishes and regards.
> > >
> > > ----------------
> > > Huang,song
> > > [email protected]
> >
>
> Best wishes and regards.
>
> ----------------
> Huang,song 黄松
> [email protected]

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System