Re: [foxboro] Sequence code

From: "Steinbrecher, Nick" <E.Steinbrecher@xxxxxxxxxxxx>
To: <foxboro@xxxxxxxxxxxxx>
Date: Fri, 1 Oct 2010 09:12:47 -0400
Having done a lot of HLBL programming I agree with AJ's rule except I
would put in one corollary.

When doing logic in calc blocks don't get too fancy.  There are some
pretty nifty instructions that are tough to follow and document if you
are not a Boolean logic wizard.  We had one of those wizards and it is a
very trying experience to  figure out what is going on.  If there is any
complexity we tend to go to sequence blocks where you can put extensive
comments ( which don't take up space in your CP).  However sequence
blocks can get large and then begin to effect your ability to
checkpoint, so keep an eye on your checkpoint file size. 


>Nick Steinbrecher
>

-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of Landry, Scott
Sent: Thursday, September 30, 2010 11:28 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] Sequence code



   Some tips from AJ, I save just about all of them.


[alex.johnson@xxxxxxxxxxxxxxxx]
Sent: Thursday, September 25, 2008 8:48 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] One IND block per compound -- still true?
I thought this would be a good time to review my implementation
guidelines:
There are a few rules that one should follow when designing a control
system:
* Do it in regulatory control blocks. (most efficient; least prone to
  problems)
* If the regulatory control blocks can't do it, use a CALC block.
  (efficient, but must deal with BAD and coding errors; debugging is a
pain) 
* If the CALC block can't do it, use a Sequence Block (pretty
inefficient,
  but in the CP. Code/compilation relatively complex. Debugging is a
pain.) 
* If you can't do it in a sequence block, reconsider if you need to do
it.
* If you must do it, see if you can do it in a shell (sh, ksh, csh,
perl,
  etc.) script (easier to debug, easy to schedule, remember to use
omgetimp
  and omsetimp to avoid broadcasts, remember to use show_params to check
the
  IMPORT table)
* If you can't do it in a script, reconsider doing it.
* If you must do it, see if there is a 3rd party or Foxboro package that
  will do it. (Ask on the mailing list.) 
* If you must do it and can't find a package, write a program.
If you are going to use HLBL, keep the following in mind:
* 1 line of HLBL code is roughly the same load as an AIN block.
* External OM variable references, e.g., :C:B.P when the compound is in
a
  different CP, suspend the block for one full block period. Thus, 20
  lines setting values will take 10s to execute if the PERIOD is 0.5s.
* Internal block references don't suspend the block, but they are slower
  than you might expect and will have an impact on your loading if you
  have enough of them.
* Remember that code runs until it hits a WAIT, WAITUNTIL, External
  Reference, or BPCSTM is reached.
* Remember that if you don't loop you code back to the top (yes,
  with a GOTO), it will reach the end of the block and stop.
* Remember that ACTIVE and MA must both be set to true for the block to
run.



   Regards,


    Scott

________________________________________
From: foxboro-bounce@xxxxxxxxxxxxx [foxboro-bounce@xxxxxxxxxxxxx] On
Behalf Of Whitworth, Terry [twhitwor@xxxxxxx]
Sent: Thursday, September 30, 2010 10:13 PM
To: foxboro@xxxxxxxxxxxxx
Subject: [foxboro] Sequence code

Looking for some help understanding and using sequence code. Is there
documentation that explains this side of the I/A?

Terry Whitworth
GBP Process Control Group
Morrilton,Ark 72110
501-354-9238 office#
501-589-7707 cell# text#
twhitwor@xxxxxxx

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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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Re: [foxboro] Sequence code

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