AIM*Historian has event triggered data.
The "Old/Legacy/IA Series" Historian is strictly change driven. Changes can
be generated based on:
1) Delta violations
2) Status Bit changes
So, I think your options are:
1) Use a variable with a known "ignore me" value and the "good" value
and toggle between them. For example, put the good value on input 0 of a
SWCH and the "ignore me" on input 1 and use a switch to toggle between them.
This is pretty ugly though.
2) Use a CALC block and store your value in one of its outputs. For one
block period between updates, use the appropriate CALC block instruction to
set the ERROR, BAD, or OOS bit. This will cause a change to be generated.
The value will be the same as before, but the historian will record the new
status. If you were to trend this result, you would see small downward
spikes between good values. Average calculations and the rest should be okay
since the Historian weights the calculation based on the time span for each
good value. 0.5s is pretty short assuming the good value hangs around for a
couple of seconds.
Does this make sense?
Regards,
Alex Johnson
The Foxboro Company
10707 Haddington
Houston, TX 77043
713.722.2859 (v)
713.722.2700 (sb)
713.932.0222 (f)
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
-----Original Message-----
From: David Johnson [SMTP:[EMAIL PROTECTED]]
Sent: Wednesday, August 30, 2000 9:15 AM
To: [EMAIL PROTECTED]
Subject: Event triggered data collection
Hello all,
I was wondering if there is a good way to do event triggered data
collection in the legacy (Informix) historian. Ideally I would like
to
place a value in the historian only when a counter increments. Is
there a
way to do this at the historian configuration level, or do I need to
write
some C code to take care of it? Any thoughts on this would be
appreciated.
Regards,
David
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