PLC5/80E to ControlLogix Conversion

Hi All!
I am going over some PLC 5 code in preparation of an
upgrade to a ControlLogix processor.
A rung of code in the 5 has a compute block with the following statement and result. (S:19*100)|S:20=210 S:19=2 S:20=10 how is this possible.

I put the same CPT instruction in one of my programs, I came up with 20. Check that your destination word is not being acted upon somewhere else in the program. If something else is changing the value of your destination word you will only see the final result when looking at RSL5. The software will not display the intermediate result to you, if you need to know what that value is then you need to use another word for the destination and then use that word as an input for the rest of the calculations.

I have checked to be sure that word is not getting stepped on
by anything else. Not what sure to think at this point.

can you post the program?

Christoph said:

A rung of code in the 5 has a compute block with the following statement and result. (S:19*100)|S:20=210 S:19=2 S:20=10 how is this possible.

Click to expand...

Just out of morbid curiosity, what is the point of this compute instruction? S:19 is the month & S:20 is the day.

Since these are status words, you may try buffering them ahead of the CPT and using the buffered data instead just for kicks.

Not sure yet what the programmers thinking was. It is part of
a serialized part number generator for product labels

Looks like an attempt to do an ordinal day of the year but the vertical bar in the compute statement says to divide (I thought). But in the PL5 maybe it was elsewise.
So bump the month up by multiplying by 100 and make room for the day (where the '00' appears in the 100) and then stick in the day.
But, not sure how the math works out in the original code

Christoph said:

Not sure yet what the programmers thinking was. It is part of a serialized part number generator for product labels

Click to expand...

Funny, but it sounds to me like they'd want to multiply month by 100, then ADD the day of month to get this result.

datatomega said:

Looks like an attempt to do an ordinal day of the year but the vertical bar in the compute statement says to divide (I thought). But in the PL5 maybe it was elsewise.

Click to expand...

You are correct; the vertical bar does mean divide in RSLogix5.

Christoph said:

(S:19*100)|S:20=210 S:19=2 S:20=10

Click to expand...

Maybe I'm a bit slow, but you may want to double check that equation as your result and the intended purpose indicate you're adding the day, not dividing by it. Maybe post a screen shot.