Experimental Physics and Industrial Control System
Thanks for the info. I don't fully understand the issue... Is there any workaround? Or in which cases the "dec" filter works?
Cheers,
Juan
On 2020-07-01, 18:22, "Michael Davidsaver" <mdavidsaver at gmail.com> wrote:
On 7/1/20 9:09 AM, Juan F. Esteban Müller wrote:
> Hi Michael,
>
> Thanks for your reply.
>
> I was suspicious, because I had the feeling I used it in the past... Can you maybe then give me a clue why I can't make it work in a simple example?
>
> This is my db file:
> record(calc, "Test:counter") {
> field(INPA, " Test:counter")
> field(CALC, "A+1")
> field(SCAN, "1 second")
> }
>
> And I run it using softIocPVA.
>
> If I do
> camonitor 'Test:counter.{"dec":{"n":2}}'
> I get every second update, while if I do
> pvmonitor 'Test:counter.{"dec":{"n":2}}'
> I get nothing. Funny enough, if I do
> pvmonitor 'Test:counter.{"dec":{"n":1}}'
> then I get every update...
>
> I am using base 7.0.4, but I also tested 7.0.3.1, which is the one I used in the past when testing the filters.
Oh, right. With the 'dec' filter you're seeing the effects of:
https://github.com/epics-base/pva2pva/issues/32
Specifically:
> QSRV assumes that the first DBE_PROPERTY update will never be dropped.
> If such an update is dropped, the subscription stalls.
I don't have a full solution to this yet.
Part of https://github.com/epics-base/epics-base/pull/71
includes a change to Base which will allow filters to distinguish
value and meta-data updates. Of course this won't necessarily
help with older Base versions.
QSRV could also be changed to not wait for the initial meta-data
update. The result would be a double initial update for most new subscribers.
There is nothing really wrong with this, I just found it annoying.
> Cheers,
> Juan
>
> On 2020-07-01, 15:39, "Michael Davidsaver" <mdavidsaver at gmail.com> wrote:
>
> On 7/1/20 2:59 AM, Juan F. Esteban Müller via Tech-talk wrote:
> > Hi all,
> >
> >
> >
> > I would like to know if there is anything equivalent to the CA decimation filter in PV access.
> >
> > https://epics.anl.gov/base/R7-0/4-docs/filters.html#Decimation-Filter-dec
>
> These filters are implemented at the database level, and so work both with CA and PVA
> (via. the RSRV and QSRV server implementations).
>
>
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