Experimental Physics and
Industrial Control System

"Mark Rivers" <[email protected]> · Mon, 11 Aug 2008 13:45:34 -0500

You need to tell us:

- What records are you using?  Are these standard EPICS records, or
records you have written.

- What device support are you using?  Did you write it?

I don't believe there is any problem with posting monitors on waveforms
at >10Hz, I do it frequently and I don't think I am having any problem.

I suspect there is a problem in your record support or device support.

Can you send the code where the calls to db_post_events is done?

Mark

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Dehong Zhang
Sent: Monday, August 11, 2008 1:34 PM
To: Tim Mooney
Cc: [email protected]
Subject: Re: Loosing half the monitor callbacks

Hi Tim (and Jeff),

There seems to be a little imperfection somewhere.

In my record, I try to "monitor" 2 fields: a float and an array of
floats
(288 elements).  What I want is to get updates at about 5Hz.  It does
not work -- missing every the other update but get those lucky ones
twice -- still getting 5 Hz but half the information.

I tried to slow down the system to about one update every 3 seconds.
It still behaves the same way.  However when I commented out the
db_post_event for the array, the monitoring for the single float works
correctly.  The problem seems to be related to the array.

In the Tech-Talk DB, Jeff once replied to someone about buffering
in Epics (the guy had very similiar problem).  Am I hit by the same
thing?
It is hard to imagine that at 0.3 Hz I would run into buffer-full or
out-
of-memory problems.  I would imagine that at a slow enough rate,
it should work with whatever buffering or flowControl.

Is there a way to re-config the IOC so that it can 'monitor' small
arrays
at <= 10 Hz?  My processor has 500 MB memory.

Thank you very much.  Best regards,
Dehong

----- Original Message -----
From: Tim Mooney <[email protected]>
Date: Saturday, August 9, 2008 11:17 am
Subject: Re: Loosing half the monitor callbacks
To: Dehong Zhang <[email protected]>
Cc: [email protected], [email protected]

> Dehong,
> I think this shows that the problem is not in channel access, but in
the
> database or lower.  You're not losing monitor callbacks, the record is
> posting the same value twice, with the same time stamp.  You can get
> another clue to what this means by looking at the record-support code,
> and finding calls to recGblGetTimeStamp() and calls to
db_post_events()
> for the CTME field.
> 
> Dehong Zhang wrote:
> > Hi Friends Kay, Mark and Mohan,
> > 
> > Thank you very much for the advices.
> > 
> > I just tried camonitor.  It is doing the same thing: throw away 
> every the other
> > change, but callback two times for the other ones.  The printout is 
> like:
> > 
> > fastTimeTest.CTME              2008-08-08 16:46:02.609123 
> 6.88202e+06 
> > fastTimeTest.CTME              2008-08-08 16:46:02.859123 
> 7.38478e+06 
> > fastTimeTest.CTME              2008-08-08 16:46:02.859123 
> 7.38478e+06 
> > fastTimeTest.CTME              2008-08-08 16:46:03.259123 
> 8.01506e+06 
> > fastTimeTest.CTME              2008-08-08 16:46:03.259123 
> 8.01506e+06 
> > fastTimeTest.CTME              2008-08-08 16:46:03.659123 137329 
> > fastTimeTest.CTME              2008-08-08 16:46:03.659123 137329 
> > fastTimeTest.CTME              2008-08-08 16:46:04.059123 817524 
> > fastTimeTest.CTME              2008-08-08 16:46:04.059123 817524 
> > 
> > Does the record update time stamps tell anything?  Am I running too 
> fast?
> > 
> > Thank you again.  Best regards,
> > Dehong
> > 
> > 
> > 
> > 
> > 
> > ----- Original Message -----
> > From: Mohan Ramanathan <[email protected]>
> > Date: Friday, August 8, 2008 4:43 pm
> > Subject: RE: Loosing half the monitor callbacks
> > To: Dehong Zhang <[email protected]>, [email protected]
> > 
> > 
> >> Hi
> >> Try to set the TPRO field in the IOC to see that it is indeed 
> >> processing every time
> >>
> >> Mohan
> >>
> >> ----------------------------------------------------------------
> >> Mohan Ramanathan  ([email protected])
> >> Senior Beamline Engineer, Advanced Photon Source
> >> Argonne National Laboratory, Argonne, IL 60439
> >> (630)-252-3773/ (630)-822-5625(Cell)
> >> ----------------------------------------------------------------
> >>
> >> [Message delivered by NotifyLink]
> >>
> >> ----------Original Message----------
> >>
> >> From: Dehong Zhang <[email protected]>
> >> Sent: Fri, August 08, 2008 4:30 PM
> >> To: [email protected]
> >> Subject: Loosing half the monitor callbacks
> >>
> >>
> >> Hi,
> >>
> >> I would like to monitor a PV at 5 Hz.  Somehow I do get 5 callbacks

> 
> >> every seconds
> >> but only get the changes every the other time, like getting changes

> 
> >> 1st, 3rd, 5th ...
> >> two times, but never get changes 2nd, 4th, ...
> >>
> >> Could you please enlighten me?
> >>
> >> Thanks and best regards,
> >> Dehong
> >>
> 
> -- 
> Tim Mooney ([email protected]) (630)252-5417
> Beamline Controls & Data Acquisition Group
> Advanced Photon Source, Argonne National Lab.

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System