PLC 5 Compute analog

scstroud · Sep 26, 2008

Can you guys help me interpet this CPT in the PLC5 program? Is there a place that gives an explaination of the characters and such?
thanks in advance.

Dest N9:60
2115 <
Expression
(((1.5 | 1.5)*((N67:11 | 4095.0)*(N9:64-N9:63)))+N9:63)+2740.0

Mickey · Sep 26, 2008

See PDF below

TConnolly · Sep 26, 2008

The | symbol indicates division.

Why is 1.5 being divided by 1.5? Then multiplying it by the rest does nothing. You could eliminate that entire part of the statement.

((((N67:11 | 4095.0)*(N9:64-N9:63)))+N9:63)+2740.0

The equation appears to be scaling a 12 bit analog value.

The entire PLC/5 instruction set reference manual can be downloaded from AB's literature library.

http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1785-rm001_-en-p.pdf

OkiePC · Sep 26, 2008

Since all of the operands are integers, I believe the (1.5|1.5) is used to typecast the interim calculations as floating point.

TConnolly · Sep 26, 2008

Entering 4095 as a float, 4095.0, should do the same thing.

I was thinking that whoever wrote the program first wanted to tweak the result by trial and error and eventually settled on a non-tweak of 1.0.

scstroud · Sep 26, 2008

Mickey I can't get that pdf file to open or print. Thanks

Mickey · Sep 26, 2008

scstroud said:
Mickey I can't get that pdf file to open or print. Thanks

Its from the manual that Alaric gave you a link to .(see below)
I just tried it again and it works for me ???

http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1785-rm001_-en-p.pdf

PLC 5 Compute analog

scstroud

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Mickey

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scstroud

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Mickey

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