Re: [foxboro] just a tip
- From: duc.do@xxxxxxxxxxxxxx
- To: foxboro@xxxxxxxxxxxxx
- Date: Wed, 19 May 2004 08:38:24 -0400
>For some reason, the SCI of 7 (low flow cut-off) doesn't work for me,
>even though it's a pretty plain-jane mass meter sending 4-20mA signal
>through an FBM 4.
Minor correction: I'm at work now and can confirm that it's actually SCI of
10 that we tried to use for low cut-off for this 12800-64000 linear raw
count signal. Nonetheless, SCI of 10 does NOT work either, and the reason
for that is plain to see when one looks at the logic for SCI=10 in B0193AW:
SCI = 10: Linear 12800 to 64000 raw counts with low cutoff
IF raw_value <= 12800
THEN
converted_value = LSCO1;
ELSE
converted_value = ((raw_value - 12800) * (HSCO1 - LSCO1) /
51200) + LSCO1;
So, there you have it. The low cut-off is ... zero!
Duc
--
Duc M. Do
Dow Corning Corp.
Carrollton Plant
Carrollton, KY, US
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx
[mailto:foxboro-bounce@xxxxxxxxxxxxx]On Behalf Of Duc M Do
Sent: Tuesday, May 18, 2004 11:10 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] just a tip
At 04:28 PM 5/18/04 -0400, Jaime Claramunt R. (Inforsa) wrote:
>hey list,
>
>does anybody have a tip for this ...
>we have some flowmeters (AIN) that still indicates some when there is no
>flow...
>this is used then in ACCUM blocks, and I want to find the way to indicate
>this block to accumulate only values over a low limit...with limits ?
>clamping ? (without hold ...)
I don't understand your "without hold ..." comment, but am going to
toss out my solution anyway. Here goes....
For some reason, the SCI of 7 (low flow cut-off) doesn't work for me,
even though it's a pretty plain-jane mass meter sending 4-20mA signal
through an FBM 4. My solution: I tie the close limit switch of the
block valve going to this meter to the HOLd parameter of the ACCUM
block: valve closes, ACCUM goes into hold and stops accumulating.
(Yeah, I know, one of these days the limit switch is going to fail and
somebody will have to fiddle with the ACCUM block, but it works well for
now.)
Hope this helps.
Duc
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