Re: [foxboro] Controller Issue after upgrade
- From: Corey R Clingo <corey.clingo@xxxxxxxx>
- To: foxboro@xxxxxxxxxxxxx
- Date: Wed, 6 Jun 2012 16:13:33 -0500
Patrick beat me to it. Foxboro's PID being a "positional" (absolute)
algorithm, this has been the case in my experience (the ramping is of
course caused by your INT/BTIME being nonzero). It took some getting used
to when I came from Brand H, which uses a "velocity"
(incremental/differential) calculation method for its outputs.
Corey Clingo
From: "foxpat" <foxpat@xxxxxxxxxxxxx>
To: <foxboro@xxxxxxxxxxxxx>
Date: 06/06/2012 04:04 PM
Subject: Re: [foxboro] Controller Issue after upgrade
Sent by: foxboro-bounce@xxxxxxxxxxxxx
David,
In PD mode there is no integral and if .ERROR = 0.0 the output will be 0.0
so it seems like normal behavior.
If you want the output to be something different, say 50% you can set this
in the .BIAS in which case you have defined the 'working-point' to be at
50%
which typically could make more sense depending on the application.
So, maybe your configured parameters are identical with the CP30 but if
the
.BIAS was set from the detail display and no upload was done then maybe
you
are now missing the .BIAS value?
Regards,
Patrick Martens
Zeeland Refinery
-----Oorspronkelijk bericht-----
Van: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
Namens Johnson, David
Verzonden: woensdag 6 juni 2012 22:20
Aan: foxboro@xxxxxxxxxxxxx
Onderwerp: [foxboro] Controller Issue after upgrade
Hello all,
We are looking into some strange behavior after a recent upgrade from a
CP30
to an FCP270. A PIDA block was set to be Proportional Derivative,
MODOPT=3,
PBAND = 125, INT=0.075 (INT is BTIME in PD mode). The BCALCI and FBK were
both connected to the PIDA's own .OUT parameter. The Period is a 3, Phase
is a 2. I think the BPC of the CP30 and FCP270 are both .5 seconds.
Behavior
In the FCP270, the output drives to the low output limit. It's as though
the loop is in open loop control. Looking at trends indicate that this
loop
was controlling in the CP30. The configuration is identical to what it
was
in the CP30.
Any advice on what to check.
Thanks,
David
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