Re: [foxboro] CHARC block BCALCO generation
- From: Corey R Clingo <corey.clingo@xxxxxxxx>
- To: foxboro@xxxxxxxxxxxxx
- Date: Wed, 22 Mar 2006 12:07:35 -0500
Yes, I guess you are right. For PRIBLK to be 1, the curve must be
continuously increasing or decreasing, so I guess if PRIBLK = 0, it
doesn't even bother trying to calculate the BCALCO. In this case, the
other "baggage" that PRIBLK carries with it caused the problems.
I ended up doing what you said and used BIAS blocks to terminate the init
chain and soak up the bumps. I'll probably redesign the scheme later on,
as I'm still not totally happy with it, but it seems to be working well
enough for now.
Thanks,
Corey
"O'Brien, Con" <con.obrien@xxxxxx>
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03/21/2006 03:02 PM
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Re: [foxboro] CHARC block BCALCO generation
I believe this is as-designed.=20
You can only configure a characterisation containing a 'peak' if you set
PRIBLK=3D0. If there's a peak in the curve (ie. it's not continuously
moving in one direction...what's the mathematical term for this?) then
it's not possible to generate a unique value for BCALCO for any value of
BCALCI. So I guess the designers included this as a genuine feature...to
allow you to put such curves in, BCALCO calculation has been disabled
when PRIBLK=3D0.=20
You can check this by trying to configure a curve containing a peak with
PRIBLK=3D1. The ICC will tell you where to go. If you turn PRIBLK off, =
it
goes in fine.=20
If you still need the BCALCO value in your control scheme, you can
configure a dummy BIAS block upstream of the CHARC, and use it to
terminate the initialisation chain.=20
Con O'Brien
Bulwer Island
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of Corey R Clingo
Sent: Wednesday, 22 March 2006 2:32 AM
To: foxboro@xxxxxxxxxxxxx
Subject: [foxboro] CHARC block BCALCO generation
Hi list,
I noticed while troubleshooting some control logic the other day that
CHARC blocks will not continuously update the BCALCO parameter when
PRIBLK is not 1. Unfortunately in the scheme we're using I cannot set
PRIBLK to
1 as there is not always an upstream propagation path for it.
Is this as-designed behavior? I don't believe I've noticed this
phenomenon on other blocks, but I plan to experiment if I get time. I
took a quick look at the docs, but they don't explicitly mention this.
Thanks,
Corey Clingo
BASF Corp.
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