Re: [foxboro] help with logical testing
- From: Corey R Clingo <clingoc@xxxxxxxxxxxxx>
- To: foxboro@xxxxxxxxxxxxx
- Date: Tue, 17 Jan 2006 16:50:07 -0600
Maybe I'm missing something, but how about adding them all up, then
testing if the result is >1, like so:
IN BI01
IN BI02
. . .
IN BI16
ADD 16
SUB 1.5 <--may have to do this with a memory reg, can't recall right
now
SSP BO01
CLR BO01
On a side note, some CALC instructions for packing/unpacking bits would be
nice, especially since they have the logical instructions that work with
packed integers. I have had to use PAKIN blocks and such to do this in
the past.
Corey Clingo
BASF Corp.
brad.s.wilson@xxxxxxxxxxxxxx
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[foxboro] help with logical testing
I've been struggling to find an elegant solution to this problem (meaning
one that runs fast). I would like to monitor several boolean inputs
(let's
say 16) and generate a boolean FALSE is no inputs are TRUE or if *only* 1
input is TRUE, otherwise generate a boolean TRUE. The application is a
valve manifold where we want to generate an alarm if 2 or more valves are
open (or not closed). We used to do this in PLB, but we abandoned that
method (I won't go into the reasons why). We're currently using an IND
block, but the extensive testing of combination is very slow ... it can
take upwards of 30 seconds to run through all the combinations.
I tried building something using CALC, but I couldn't find an operation
that worked among AND, OR, NOR, NAND, XOR, XNOR, etc. I looked at MCIN,
but I don't see how that would work (the inputs are on different FBMs). I
tried to understand how I could manipulate the inputs into a packed
integer, but didn't get very far with that.
Any ideas?
Brad Wilson
ExxonMobil Chemical Co
Edison Synthetics Plant
732-321-6115
732-321-6177 fax
Brad.S.Wilson@xxxxxxxxxxxxxx
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