This has been an interesting discussion. I've personally never used PLBs,
because I didn't need the processing speed that they give (in truth, I'm
not sure it's really any faster, but I presume the FBM processes logic at
a somewhat greater rate than the CP), and I try to avoid YAT (Yet Another
Tool) unless the benefit warrants it. But I've never needed PLBs, either;
CALCA/LOGIC blocks, CINs, COUTs, and GDEVs provide all the tools I have
ever needed for discrete interlocks. And locking of appropriate
parameters (via connection to themselves or other blocks) provides
adequate protection from changes (though I still would like to see a
system-wide security mechanism, enforced at the CP level).
Corey Clingo
BASF Corp.
"Dirk Pauwels" <dirkpauwels_1@xxxxxxxxxxx>
Sent by: foxboro-bounce@xxxxxxxxxxxxx
05/12/2005 02:40 AM
Please respond to foxboro
To: foxboro
cc:
Subject: Re: [foxboro] Reduce IFL's for FBM
We're using PLB's, cause it's the easiest way to configure Interlocks,
unfortunately the number of IFL's also limit the interlocking, so we''re
also using seq/calc etc for interlocking. The disadvantage of using seq
code
interlocking is that the blocks can still be activated via select. With
PLB
interlocks, the blocks cannot be operated from the select unless all
interlocks are OK.
For Motor and valve control we use GDEV's and PLB's, for valves we use 2
cin's/ofl's for open/close feedback and 1 CO for open and close. For
motors
we're only using the running cin/ofl and 1 CO. The ofl's are connected to
the DEVLM's of the GDEV. STAIND is used to show status on screen
We can attach 8 motors to an FBM(2)41 or 42 card, or 4 valves. The number
of
IFL is not really the limit here, but there are only 8 Co's on a FBM41/42.
Using FBM242 you would have 16 Co's
I'll send Daniel an example offlist.
Rgds,
Dirk Pauwels - DCS coordinator
Engineering dept.
Lawter International BVBA
An RSM Company
Ketenislaan 1c ? Haven 1520
B-9130 Kallo, Belgium
T. +32.(0)3.570.95.97/ Mob. +32.(0)497.428.300
F. +32.(0)3.570.16.09
E mail: dirk.pauwels@xxxxxxxxxx
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