Re: [foxboro] just a tip

>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

 
 
_______________________________________________________________________
This mailing list is neither sponsored nor endorsed by Invensys Process
Systems (formerly The Foxboro Company). Use the info you obtain here at
your own risks. Read http://www.thecassandraproject.org/disclaimer.html
 
foxboro mailing list:             http://www.freelists.org/list/foxboro
to subscribe:         mailto:foxboro-request@xxxxxxxxxxxxx?subject=join
to unsubscribe:      mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave

Other related posts: