Re: [foxboro] Ain FLOP
- From: tom.vandewater@xxxxxxxxxxxxxx
- To: foxboro@xxxxxxxxxxxxx
- Date: Thu, 12 May 2005 16:36:38 -0400
Dirk,
Some of our engineers love the Filter Option but I have removed a
lot more of them than I've added. They do have their place but too many
times I've found a .FTIM=1 or greater on a flow that is being used by a
controller. The engineers think they have smoothed the controller operation
when all they did was make the controller extremely unresponsive to changing
process conditions.
Now, off the soapbox! This made us pull our hair out for a while but
we figured it out. When you use Filter Option, (FLOP=1), on an AIN block
connected to an FBM point, (IOMOPT=1), the filter uses the .RAWC value as
input and sends its output to the .MEAS which passes to the .PNT. In this
case you see the .MEAS and .PNT follow each other. When using FLOP=1 and
IOMOPT=2 the filter uses .MEAS as the input and sends its output to the .PNT
and the .MEAS value is unfiltered and the .PNT is filtered. This is very
confusing but I'm positive that is how it works at Ver. 6.2.1 that we are
running. The way we tested was to hook up a 4-20ma source to an FBM input
so we could easily and rapidly change the FBM input signal from 4 to 12 MA.
Then it was obvious what was happening. We could see the .RAWC value change
immediately from 12,800, (4MA), to 38,400, (12MA), but watched both the
.MEAS and .PNT gradually change based on the filter time, (.FTIM), we
entered. So, Dirk, the filter is probably being applied even though it is
very difficult to tell, because both the .MEAS and .PNT are changing
together. You should be able to change the .FTIM to a higher number and see
a change in the amplitude of the oscillations though.
You had .FTIM set at 0.50 which is half a minute. Hope this helps!
Tom VandeWater
Control System Developer/Analyst
Dow Corning Corporation
Carrollton, KY USA
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On
Behalf Of Dirk Pauwels
Sent: Thursday, May 12, 2005 7:28 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] Ain FLOP
We have CP60, version 6.5.1 according to the station block. Tried
checkpointing & exit, delete & undelete, delete & rebuild from scratch
etc... the data is not filtered with iomopt at 1, rerouted to a new AIN
block and IOMOPT = 2 it works. I don't get it?????
>From: "Johnson, Alex (Foxboro)" <ajohnson@xxxxxxxxxxx>
>Reply-To: foxboro@xxxxxxxxxxxxx
>To: foxboro@xxxxxxxxxxxxx
>Subject: Re: [foxboro] Ain FLOP
>Date: Thu, 12 May 2005 07:21:12 -0400
>
>It is supposed to work. Contact the CSC.
>
>What version of the CP are you running by the way - Check the STATION block
>detail display.
>
>Regards,
>
>Alex Johnson
>Invensys Process Systems
>Invensys Systems, Inc.
>10707 Haddington
>Houston, TX 77043
>713.722.2859 (voice)
>713.722.2700 (switchboard)
>713.932.0222 (fax)
>ajohnson@xxxxxxxxxxx
>
>-----Original Message-----
>From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On
>Behalf Of Dirk Pauwels
>Sent: Thursday, May 12, 2005 7:18 AM
>To: foxboro@xxxxxxxxxxxxx
>Subject: [foxboro] Ain FLOP
>
>In an AIN block, if I set FLOP = 1 and Dtime = 0.50 the data gathered from
>FBM channels (IOMOPT= 1) is not filtered, filtering does not work. If I
>create an extra AIN block, IOMOPT = 2 and MEAS = first AINblock.PNT then
>the
>
>filtering option works. I guess it's not possible to filter the data
>directly or do I need to set another parameter?
>
>Thanks,
>
>Dirk Pauwels - DCS coordinator
>Engineering dept.
>Lawter International BVBA
>An RSM Company
>Ketenislaan 1c - Haven 1520
>B-9130 Kallo, Belgium
>T. +32.(0)3.570.95.97/ Mob. +32.(0)497.428.300
>F. +32.(0)3.570.16.09
>E mail: dirk.pauwels@xxxxxxxxxx
>
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_________________________________________________________________
_______________________________________________________________________
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: //www.freelists.org/list/foxboro
to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join
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_______________________________________________________________________
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: //www.freelists.org/list/foxboro
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