Re: [foxboro] Foxboro Control Philosophy 101

A CHARC block can be used as an extender block to the AIN block, to
implement a low signal cutoff.  See EXTBLK parameter.  One CHARC block can
characterize many AIN blocks, so you are not necessarily adding one block
per loop - could be a fraction of a block per loop.
Steve

> -----Original Message-----
> From: foxboro-bounce@xxxxxxxxxxxxx@CORP  On Behalf Of "Charlie Doran"
> <cdoran@xxxxxxxxxxx>
> Sent: Friday, October 26, 2001 11:11 PM
> To:   foxboro@xxxxxxxxxxxxx
> Subject:      Re: [foxboro] Foxboro Control Philosophy 101
> 
> 
> If it is of any help, the Foxboro IDP10 and earlier 863DP and a low-flow
> cutoff available as part of the transmitter setup, so long as the
> transmitter was in square root mode (output linear with flow) On IDP10,
> there are two mode: soft cutoff and clamp. Might be easier to do it there
> (assuming you have this kind of transmitter) than in the I/A system.
> 
> Charlie Doran
> Invensys Systems (Foxboro)
> ----- Original Message -----
> From: "Corey R Clingo" <clingoc@xxxxxxxxxxxxx>
> To: <foxboro@xxxxxxxxxxxxx>
> Sent: October 26, 2001 10:19 AM
> Subject: Re: [foxboro] Foxboro Control Philosophy 101
> 
> 
> >
> > We've used SCI 7 on square-rooted inputs, as they tend to be noisy down
> low, but
> > 3/4% is not always enough to silence the spurious readings.  And this
> isn't
> > available on linear inputs, unless you use a 0-64000 SCI and adjust your
> ranges
> > accordingly, which then would make the bad-loop detection too sensitive
> on
> the
> > low end (and talk about troubleshooting confusion!).
> >
> > On the other system I've used (starts with an "H" ;-), there is a low
> cutoff
> > parameter, which causes the displayed input to got to zero if the actual
> input
> > was between (low range - OSV) and that parameter.  Worked great.  But
> the
> KSCALE
> > thing here looks good, too, except that you have to use another block.
> >
> > Corey
> >
> >
> >
> >
> >
> > William C Ricker <wcricker@xxxxxxxxxxxxxxx> on 10/25/2001 05:24:12 PM
> >
> > Please respond to foxboro@xxxxxxxxxxxxx
> > To:   foxboro <foxboro
> > cc:
> > Subject:  Re: [foxboro] Foxboro Control Philosophy 101
> >
> >
> >
> >
> > Low Cutoff SCI's are:
> > SCI =  6: Square root, low cutoff (0 to 64000), clamp < 3/4% ("0 to
> 100%")
> > SCI =  7: Square root, low cutoff (12800 to 64000), clamp < 3/4% ("20 to
> > 100%")
> >
> > SCI =  9: Linear, low cutoff (1600 to 64000) ("0 to 100%, Elevated
> Zero")
> > SCI = 10: Linear, low cutoff (12800 to 64000)("20 to 100%")
> >
> > SCI = 13: Square root, low cutoff (14080 to 64000),("20 to 100%,
> Elevated
> > Zero")
> >
> > HOWEVER,
> > I have thought (but never tried) to bring a boolean value into the
> KSCALE
> of
> > the
> > AIN.
> > When its set, you would get VALUE * 1 or VALUE
> > When its not, you would get VALUE * 0 or 0
> >
> > The theory sounds good, no?
> >
> > W C Ricker
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > ___________________________________________________________________
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> >
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> >
> 
> 
> 
> ___________________________________________________________________
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> 
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