Re: [foxboro] AW: Increment Values

I think what you need is a LIM block by configuring it as following
MEAS: Value entered by the operator
ROCOPT: true
ROCLIM: step value
FOLLOW: FALSE

The OUT will be equal to MEAS+ROCLIM, each cycle the out will be
increased by the ROCLIM. I have already used this configuration where
the spped of the pump can't go suddenly to the desired value, it must
follow an increment.

Mohamed Abbas Helmy
Senior Application Engineer
Invensys-EGYPT


On Fri, 18 Feb 2005 07:40:14 +0100, Hegewisch, Dirk
<Dirk.Hegewisch@xxxxxxxxx> wrote:
> Hi,
> thanks for your answer, but that isn't an good solution for me.
> 
> I try to describe it better:
> In our plant the operator select an C:B.P with $PICK1 an then
> he will change the value.
> So it isn't possible to give the right range for each Point.
> 
> I am looking for an solution that only increase/decrease (any value)
> with an fix value. Like +/- 0.5.
> And it doesn't care if we have %, =B0C, t, m=B3/h, .... or what ever.
> 
> Regards,
>  Dirk
> 
> -----Urspr=FCngliche Nachricht-----
> Von: Johnson, Alex (Foxboro) [mailto:ajohnson@xxxxxxxxxxx]=20
> Gesendet: Donnerstag, 17. Februar 2005 01:07
> An: foxboro@xxxxxxxxxxxxx
> Betreff: Re: [foxboro] Increment Values
> 
> The key is the use of a range or Range Variable (Rxy).
> 
> The Range Variables (Rxy) parameters are OM objects that contain 3 =
> floating
> point values.
> 
> Rxy[0] - High scale - HSCxy
> Rxy[1] - Low scale - LSCxy
> Rxy[2] - Change Delta - DELTxy
> 
> The DM/FV is smart enough to set the big (double arrow) and small =
> (single
> arrow) ramp buttons to a percentage of the span IF the Rxy parameter is
> specified on the tag name, e.g.,
> 
> C:B.SPT|RI1
> 
> Might be used for a PIDA block setpoint ramp.
> 
> If the Rxy parameter is not specified, a default is assumed and the RAMP
> Buttons will use a percentage of that span.
> 
> If you want a custom span, you can specify it as follows:
> 
> C:B.P|R=3D<lowRng>,<hiRng>
> 
> So, try this:
> 
> Make a graphic that contains a rectangle. Configure the select action =
> ramp
> with the following line:
> =20
> C:B.SPT|R=3D2.0,98.0
> 
> Protection Class: 0
> 
> +/- percent control range: 5
> 
> Where C:B.SPT refers to some PID block setpoint in your system.
> 
> This configuration will clamp the .SPT between  2.0 and 98.0 Obviously =
> the
> custom range should be within the block's RI1 (LSCI1,HSCI1)
> 
> ****** Thanks to Leo Moramarco/FoxCanada and Ignacio Queirolo =
> Olivera/Repsol
> for some of the material above.
> 
> Regards,
> =20
> 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 Hegewisch, Dirk
> Sent: Wednesday, February 16, 2005 8:28 AM
> To: foxboro@xxxxxxxxxxxxx
> Subject: [foxboro] Increment Values
> 
> Hi Group.
> 
> I want change the value of an given C:B.P.
> The value should change up/down from current value.
> For example in +/-0.5 steps   (newvalue =3D3D oldvalue + 0.5)
> 
> The ramp function isn't the right function. Because the C:B.P increase
> by percent of the control range.
> 
> Has anybody an easy solution for this small problem?
> 
> Dirk
> 
> =20
> =20
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> Systems (formerly The Foxboro Company). Use the info you obtain here at
> your own risks. Read http://www.thecassandraproject.org/disclaimer.html
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>
 
 
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