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Subject: Re: Channel access dynamic array subscription update element count
From: Andrew Johnson <anj@aps.anl.gov>
To: Jeff Hill <johill@lanl.gov>, michael.abbott@diamond.ac.uk
Cc: tech-talk@aps.anl.gov
Date: Mon, 5 Oct 2009 11:20:25 -0500
Jeff,

While you're responding on this subject could you definitively answer 
Micheal's original questions, which were:

> Firstly, is it possible for the element count of a channel to change while
> the channel is connected?  I'm thinking in particular of the case when
> using camonitor (well, ok, I mean ca_create_subscription()) to monitor a
> waveform PV.  Each event_handler callback is informed of the dbr count --
> but as far as I can tell, it's always the maximum waveform size, even if
> NORD is smaller.

> Is the fact that the update size doesn't change, ca_element_count() always
> reports the NELM, and subscribing with zero count gets the full wavelength,
> is this restriction fundamental to channel access, a limitation of the
> channel access server, or just something that hasn't been implemented in
> the waveform record?  This question becomes more interesting as we use
> waveform records for large images!

Thanks,

- Andrew
-- 
The best FOSS code is written to be read by other humans -- Harald Welte


Replies:
Re: Channel access dynamic array subscription update element count Michael Abbott
RE: Channel access dynamic array subscription update element count Jeff Hill
javaIOC Marty Kraimer
References:
Channel access and ca_element_count michael.abbott
RE: Channel access and ca_element_count Jeff Hill
RE: Channel access dynamic array subscription update element count Jeff Hill

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