Re: [foxboro] IND Block ACHNGE concept = Change-based execution to initiate scanning
- From: "Rick Mol" <Rick.mol@xxxxxxxxxxxxxxx>
- To: <foxboro@xxxxxxxxxxxxx>
- Date: Mon, 27 Jun 2011 07:25:45 -0500
Joseph,
I've used the ACHNGE parameter with an IND block to look for changes to the
block itself from a graphic. That way, as you mentioned, the block would
park there and process only when the operator initiated an action. This
particular application was a CP based batch engine; the IND block was used
to initiate phases.
Found no problems with that implementation other than including debounce
logic or feedback in case the user developed the condition called
'clickenzeebutton'.
Regards,
Rick Mol
Coyote Technologies
231.750.6348
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On
Behalf Of Riccardi, Joseph
Sent: Sunday, June 26, 2011 3:19 PM
To: foxboro@xxxxxxxxxxxxx
Subject: [foxboro] IND Block ACHNGE concept = Change-based execution to
initiate scanning
Folks,
ACHNGE = Alternate Change is an integer output which is incremented each
time a block parameter is changed via a SET command.
Note: Each time a block parameter is changed via HLBL code, parameter
MSGNO is incremented.
Picture the GDEV Block implemented in an IND Block with HLBL. Picture
the Block set up to handle a dozen different applications (2/3-wire,
2-speed, forward-reverse, etc.) in the IND template and an integer is
set in the beginning of the code that defines the type of GDEV
application. Picture 1,000 of these GDEV-type IND Blocks. Note: Too
late to ask why at this point...
I just ran across this ACHNGE parameter and it has been suggested that
we add a few lines in the beginning of the code to WAITUNTIL ACHNGE
increments, then run the code once, then WAITUNTIL ACHNGE increments
again. Otherwise, the IND is sleeping as well as most of the other INDs
except when an input change occurs and they need to wake up and run
once. I have never run across this method and was just wondering if I
am missing something? It certainly looks like a life-saver on a system
with overload issues and 1,000 of these Blocks.
Let me make one qualifier 1st. We do not actually plan on using the
ACHNGE parameters because it is limited to changes via a SET command
only but we will build our own Integer or Packed Boolean to indicate an
input change has occurred. It is the concept that I am asking about. I
looks great to me but I do not want to change 1,000 of them just to find
an "Uh Oh" later.
I would appreciate it if anyone has used this concept before and what
are the "gotchas" I need to consider before proceeding.
Thanks,
Joseph M. Riccardi
Senior I&C Engineer
386-451-7607
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