Re: [foxboro] time delay for deviation alms (was: time delay on AIN alarm)
- From: brad.s.wilson@xxxxxxxxxxxxxx
- To: foxboro@xxxxxxxxxxxxx
- Date: Fri, 20 Jan 2006 12:50:26 -0500
>>>
On a very similar subject, does anybody have a "nifty" way to delay
Deviation alarms in PIDx or REALM blocks (and here is the limiting factor):
WHEN THERE IS NO WAY TO KNOW WHEN TO BEGIN THE ALARM DELAY - i.e. there is
no known process "Boolean" to trigger the start of the inhibit timer? It
is a simple requirement: to delay triggering the deviation alarm after the
deviation actually occurs.
<<<
I would think the principal is the same for any alarm. The trick is
whether you can inhibit/disable just the alarm you're interested in, or
must you do all the alarms in the block. (Sending a packed boolean to the
INHALM parameter is a clever way to single out alarms.) In your case (or
any case), you start the delay when the alarm trips, right? So you'd start
with the dev alarm inhibited but with INHOPT=0 (this allows the alarm to be
detected, but not alarmed). When the alarm trips and LDAIND or HDAIND goes
to 1, it starts the delay timer (in some other block, as previously
discussed). When the timer is up, it uninhibits the dev alarm, which
allows the alarm message to be sent out.
Brad Wilson
ExxonMobil Chemical Co
Edison Synthetics Plant
732-321-6115
732-321-6177 fax
Brad.S.Wilson@xxxxxxxxxxxxxx
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