Re: [foxboro] Control Block Equivalents
- From: "Ken Heywood" <kheywood@xxxxxxxxx>
- To: <foxboro@xxxxxxxxxxxxx>
- Date: Tue, 26 Apr 2005 09:29:36 -0400
Unfortunately, Foxboro never has liked to do "rule of thumb" rules. =
There was a listing for blocks and equivalents at one time for the CP30 =
and CP40. There are many more factors now affecting the performance of =
CP60 ... OM loading, block size and execution, FBM scanning ... now more =
than ever your Fieldbus architecture effects the performance too. So, =
document B0400BK is the usual Foxboro "engineer it to the nearest pixel" =
approach. "A" for effort, "D+" for rule of thumb rough guestimate.
*K
-----Original Message-----
From: Corey R Clingo [mailto:clingoc@xxxxxxxxxxxxx]
Sent: Tuesday, April 26, 2005 9:11 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] Control Block Equivalents
They have some CP sizing spreadsheets included in the FoxDoc files (I've
seen them on my CP and on the web site) Unfortunately, you either have =
to
put in a count by trial and error until you overload it, or look at the
formulas to glean this information. I haven't ever seen a "CP60 will =
hold
x blocks and process y blocks" document; this is likely because the
different block types use different amounts of memory and CPU time in =
the
CP.
What I'd like to see is a tabular listing of each block with its
static/dynamic memory requirements and relative processing power =
required.
This would help me make decisions about which block to use for a
particular application (and if memory and CPU were stated for one "block
equivalent", would help get what you are looking for as well). I =
started
to do this once from the spreadsheet formulas, but other more important
issues took precedence...
Corey Clingo
BASF Corp.
"Penndorf, Rocco (RP)" <RPPenndorf@xxxxxxx>
Sent by: foxboro-bounce@xxxxxxxxxxxxx
04/26/2005 06:04 AM
Please respond to foxboro
To: "'foxboro@xxxxxxxxxxxxx'"
cc:
Subject: Re: [foxboro] Control Block Equivalents
Hank,
this is not what I'm looking for. I want to do a rough estimate how many
control blocks I can configure in a
CP. Each CP type has the ability to hold & process a certain number =
blocks
(e.g. CP40 can hold 2000 blocks and process 3200 blocks / s). The point
is, that the different block types (PID, CALC, AIN ....) have different =
so
called block equivalents (I believe for a CALC block the block =
equivalent
is 3), which can be used to make a rough estimate which load the CP can
handle. I remember, that I've seen a list containing the block names and
the block equivalent somewhere, but
I don't remember where.
Best Regards
Rocco
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