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<== Date ==> <== Thread ==>

Subject: Alarm Handler and $ALARMCOUNTFILTER
From: <keith.baker@diamond.ac.uk>
To: <tech-talk@aps.anl.gov>
Date: Mon, 18 Jul 2011 15:34:58 +0000

Hello,

Please can someone clarify the effects of using the following command in the Alarm Handler configuration file as the user guide does not seen to fully explain the behaviour and it doesn’t seem to do what I want.

 

$ALARMCOUNTFILTER inputCount inputSeconds

 

The documentation says, the channel must remain in alarm for more than inputSeconds or enter into an alarm state more than inputCount times within inputSeconds.

To me these two conditions seem contradictory. If I only want to recognise an alarm that has persisted for inputSeconds then I want to ignore intermittent changes, not count them and go into alarm anyway.

 

My requirement is to only register an alarm if the value exceeds the threshold persistently for 120 seconds.

Is there a recommended trick with the settings to get the alarm handler to do this? Perhaps setting the inputCount to a very high value, so it can’t possibly be exceeded within the time.

 

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.

 

Again, I’d say that the documentation could be clearer and state that these settings relate to transition both into or out of alarm. It does not have any effect for transitions between MINOR and MAJOR alarm states, which occur instantly.

 

Any corrections to my understanding or suggestions to achieve the behaviour I want, would be most appreciated.

 

Thanks,

Keith Baker

 

Diamond Light Source Limited


 

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Re: Alarm Handler and $ALARMCOUNTFILTER Andrew Johnson

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