adccommunitymod (AutomationDirect) asked a question.
PAC 3000 rung analysis
Created Date: June 16,2012
Created By: kewakl
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Does anyone here know if the PAC3000 MUST evaluate ALL logic in a rung/subrung, or just enough to determine that the logic will evaluate to FALSE?
Created Date: June 18,2012
Created by: ADC_CommTeam02
Please refer to help topic P202, this explains in detail the Productivity Suite logic scan behavior.
Created Date: June 18,2012
Created by: kewakl
I want a bit more detail.
Help topic P202 just says "scan left to right. "
Should I infer that it means that it scans (evaluate) ALL elements?
Sometimes I need a bit more explaining.
This is an "I want to know " question.
Some programming languages support "short-circuit logic evaluations. "
I was curious if PAC did. If I knew it did, I would put ALL 'trigger ' elements as far left as possible. If not, then it would not matter, except for readability.
Why?
Example time:
Assume 2D array AR2S32-000001 with dimensions of 600,100 (60000 words.)
If array element (599),(75) has to be extracted and evaluated to be WITHIN A RANGE OF VALUES for a certain operation to be performed,
I would NOT NEED the PAC to extract and evaluate this array element IF it could be determined in the FIRST COLUMN that the rung would evaluate to false.
I have NO idea of the overhead required to extract this element - even though I KNOW that it is GOING to happen DURING the current scan.
Created Date: June 18,2012
Created by: bcarlton
As a side from the 'continued evaluation after a known false ' question, it is good to see from the diagrams that it doesn't have the dreaded 'AND above a JOIN ' problem/feature of the DL line.
Created Date: June 18,2012
Created by: ADC_CommTeam02
We evaluate the entire rung, we do not support "short-circuit logic evaluations. "
Created Date: June 18,2012
Created by: kewakl
Thank you.
Now I know!
Created Date: June 16,2012
Created by: kewakl
Does anyone here know if the PAC3000 MUST evaluate ALL logic in a rung/subrung, or just enough to determine that the logic will evaluate to FALSE?