You haven't corrected my understanding of how the $ALARMCOUNTFILTER behaves so at least I know I'm not missing some trick. I'll just have to work with it as it is, or like you say, implement an alternative in the IOC.
I was partly after confirmation that other people are happy with the way things are. Since you're using this feature a lot at ALH it clearly suits your needs.
I may risk proposing some backward compatible changes in the future, but this will take effort and it looks like I'm the only one who needs them.
From: Andrew Johnson [mailto:email@example.com]
Sent: 18 July 2011 17:14
Cc: Baker, Keith (DLSLtd,RAL,DIA)
Subject: Re: Alarm Handler and $ALARMCOUNTFILTER
On 2011-07-18 firstname.lastname@example.org wrote:
> My requirement is to only register an alarm if the value exceeds the
> threshold persistently for 120 seconds.
> The other behaviour I've noticed is that once in alarm, the same criteria
> is used to decide when to drop down to no alarm. i.e. if the PV value
> drops below the threshold then it takes inputSeconds before this is
> recognised, or inputCount drops within inputSeconds. I am just curious as
> to whether this is behaviour that anybody wants or uses? I'd prefer to
> drop out of the alarm state immediately.
It's likely that the behaviour implemented was required by someone at APS when
we wrote ALH, I see it being used fairly heavily in our operational alhConfig
I would suggest that your alarm filter should probably be implemented inside
the IOC, rather than rely on ALH to do it. It's much easier to customize
Optimization is the process of taking something that works and
replacing it with something that almost works, but costs less.
-- Roger Needham
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