[foxboro] AW: IND block modification
- From: "Sieling, Marcel" <Marcel.Sieling@xxxxxxxxxxxxxxxx>
- To: "'foxboro@xxxxxxxxxxxxx'" <foxboro@xxxxxxxxxxxxx>
- Date: Wed, 2 Feb 2005 07:52:05 -0500
Hafedh,
> Will all the outputs go to last good value or go to zero=20
> before this ?=20
In general a sequence block which is compiled behaves like if it was =
deleted
and undeleted from the database. So ALL values on the block detail go =
to
CYAN color and therefore are Out of Service fo a short time (I assume =
one
BPC). If you have remote connections to block parameters outside the =
current
CP they will remain out of service until completion of a checkpoint. =
All
contents of internal variables are lost during initialisation, the =
program
execution is stopped and restarted from the beginning. Inputs are read =
from
the last upload's contents, the value of outputs are also principally
undefined and without testing I currently can't definetely say if they =
are
initialized to zero or to their last upload value. However it's clearly =
not
the value they had before the compile.
So what I'm saying is: It very much depends on what there is programmed =
in
the sequence code, what happens on the outputs. If during writing of =
the
code the engineer took care about the initialization scenario and if he =
has
tested it carefully, the behaviour may be very clearly defined and =
smooth in
respect to the process. If not, the results of a compile may be at =
least
surprising, if not desaterous. ;-)
I very strongly recommend to spend a significant amount of time on
initialization design and testing while writing sequnce code. If it is =
done
properly, you even do not notice when sequence code is compiled, it
initializes completely bumpless to the process.
BTW: This implies to the error handling as well. I'm wondering, how =
many
sequence applications are out there without any standard block =
exceptions
impelemented. All those folx working with sequence programs and not =
using
standard block exceptions should really spend the time learning about =
these
and using them properly. Seek for training in case you need it.
Best regards -
Marcel Sieling
Systems Technologies
Invensys Systems GmbH
Emanuel-Leutze-Str. 11
40547 Duesseldorf
Germany
Tel.: +49-211-5966-302
Fax: +49-163-99-5966302=20
Mobile: +49-163-5966302
Email: mailto:marcel.sieling@xxxxxxxxxxxxxxxx
Homepage: http://www.foxboro-deutschland.de
> -----Urspr=FCngliche Nachricht-----
> Von: foxboro-bounce@xxxxxxxxxxxxx=20
> [mailto:foxboro-bounce@xxxxxxxxxxxxx] Im Auftrag von Ghodhbani, =
Hafedh
> Gesendet: Mittwoch, 2. Februar 2005 11:27
> An: foxboro@xxxxxxxxxxxxx
> Betreff: [foxboro] IND block modification
>=20
>=20
> Hi list,=20
> I want to add some lines to an running IND block by HLBL.editing.=20
> Please tell how will the block outputs be changed when I do=20
> "done with sequence" ?=20
> The modification is minor and should not lead to a change in=20
> the outputs immediately.=20
> Will all the outputs go to last good value or go to zero=20
> before this ?=20
>=20
> Thanks=20
> Regards=20
> Hafedh G=20
> Sr C&I Eng BG group.=20
> Tel:+21674259250 ex 574=20
>=20
>=20
>=20
> =
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