Re: [foxboro] Int30 Question

Brian,
We also use several Int30 connections.  I have not tried tying directly
to the ABSCAN.  I suspect that ultimately it does not make much
difference in throughput because I believe the bottleneck is in the
pipeline between the two processors (Int30 and PLC) and not in the
processors themselves.  We use KF2 modules at 19.2K baud on our
connections, so the pipeline is pretty slow.  Following that logic in
the case of single bits, we focus on compacting bit transfer.  We use
MCIN instead of CIN blocks.  The only requirement on the PLC side is to
assign your Boolean points in contiguous blocks--a common practice
anyway.  Leaving a few "blank spaces" for future growth is still
possible.  It just lowers the efficiency of the data transfer by passing
"air" in some spots.  Our belief is that the MCIN blocks bring over a
word's worth of bits in a single connection ("leaps tall buildings in a
single bound!").  Whether or not it makes a difference, it makes us feel
like we are making a difference.

I confess I have not connected displays to the ABSCAN blocks because I
didn't think of it.  When connecting to displays, it should only put a
load on the Object Manager.  But, it is the same load that would be put
on the Object Manager if the data were stored in CIN or MCIN blocks.
So, why build blocks that you don't need just to hold data for displays?
It sounds like a clever solution to lowering the CPU load.  But, as I
said, I don't think it will help with throughput.

Chuck Jones
Automation Technologist
Tate & Lyle -- Lafayette South Plant
765.477.5324 - Office  | 765.586.5290 - Cell




-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of BrianLong
Sent: Friday, February 10, 2006 10:31 AM
To: Foxboro
Subject: [foxboro] Int30 Question


We use a number of Int30's tied to AB plc's.  As we all know they work
well
but are limited in terms of thruput.   I'm trying to determine the best
way
to use individual bits to help with loading.   Typically we've tied bits
to
CIN's for documenting, display building and alarming.  Is it best, in
terms
of loading, to address directly from the ABSCAN?   How about when
building
displays, should I address bits directly from the ABSCAN using the
bitmap
function? (Using DM).  Not using extra blocks seems like it would help
"overall" loading but didn't know if it might tie up the individual
ABSCAN.
Thanks in advance,
Brian Long
Arkansas Kraft


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