Re: [foxboro] "GDEV" or "VLV,MOVLV,MTR" or "CALC" - Discrete control engineering advice ?

  • From: "Bruley, Peter T" <Peter.T.Bruley@xxxxxxxxxxxxxx>
  • To: <foxboro@xxxxxxxxxxxxx>
  • Date: Wed, 1 Aug 2007 14:38:31 -0500

I agree with you that while the CALCA block can do the work it is a =
"black hole" that is too custom & hard to trouble shoot for people who =
don't understand CALCA step language.=20

I Also agree that the Operator Alarming functionality is nil in a CALCA =
block and would introduce another layer of complexity to get the =
Operator Alarm functionality required.

This alarming is one of the main advantages I see with the GDEV block as =
there is are twelve(12) states (as Brad Wilson mentioned STAIND) along =
with a generic MMAIND:=20
Four Feedback States:
1       STAT1 0 state (Closed or Stopped)
2       STAT2 1 state (Opened or Running)
3       STAT3 Traveling to 0 state
4       STAT4 Traveling to 1 state
Eight mismatch alarm states:
5       MM1 0 state mismatch
6       MM1 0 state mismatch, reverse
7       MM3 0 state mismatch, both
8       MM1 0 state mismatch, DEVLM2
9       MM2 1 state mismatch
10      MM2 1 state mismatch, reverse
11      MM4 1 state mismatch, both
12      MM2 1 state mismatch, DEVLM1
----------------------------------
        MMAIND mismtch alarm indicator (when ever any of the above 8 mismatch =
alarms are set)

Only three(3) states when using MTR/VLV/MOVLV
Two Feedback States
1       RUNNING
2       STOPPED
One mismatch State
3       MMAIND mismtch alarm indicator

Using GDEV the alarming states can really come in handy when building =
graphics.

The GDEV also has a cool feature "ACTTOC" that stores the "Actual Time =
to open":

  Actual Time to Open/Run or Close/Stop is an integer output (0 to 100)
  that indicates the actual time, as a percentage of TOC, that it takes =
the
  device to travel from one state to another.



However the lead Engineer on our project has made a bold warning to us =
about using GDEV blocks:

----------------------< WARNING START >---------------------
"No power project has ever used the GDEV block to my knowledge. This =
extends to the beginning of I/A.=20
The reasons were many- mostly that the block always came up short in the =
details. All of project operations=20
is considering discontinuing the use of this block on future projects. =
The block has had a somewhat=20
checkered past with many CARs and quick fixes. If we use this block, you =
will have to accept its limitations."
----------------------< WARNING END >---------------------

Does anyone have any experience with these particular claims?  or =
basically any reason not to use GDEV?

Thanks

Peter

-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx
[mailto:foxboro-bounce@xxxxxxxxxxxxx]On Behalf Of David Vergara S.
(SANTAFE - CMPC Celulosa)
Sent: Wednesday, August 01, 2007 1:42 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] "GDEV" or "VLV,MOVLV,MTR" or "CALC" - Discrete
control engineering advice ?


2.- In a new project "some one" decided to build motor control logic =3D
with
CALCA blocks (copied from other project in Brazil). this would not be
necessarily bad, but... without a clear, unique documentation and good
comments in the steps, it can be very difficult to follow the logic and
"know" exactly what this logic does or not. the alarming functionality =
=3D
needs
to use more blocks... and so on. Maybe the Brazilian people can comment
something...

 
 
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