bernie_carlton
Lifetime Supporting Member + Moderator
I have often seen statements that arranging rungs so that the condition most likely to make the whole rung TRUE (or FALSE) should be placed to be evaluated first to speed up scan time.
This implies that, upon determining that the rest of the rung conditions are irrelevant to deciding the ultimate TRUE or FALSE state of the rung, the system will bypass (or in some way shorten the evaluation of) further conditions and jump right to output processing.
While this sounds efficient does anyone have a reference to an official technical publication which specifically states this behavior in the evaluation of rungs? (I'm thinking primarily Allen Bradley or AutomationDirect PLCs since those are the ones I'm most familiar with.) I'm looking not just for a recommendation of rung structure but an actual statement as to how this 'evaluation shortening' takes place.
This implies that, upon determining that the rest of the rung conditions are irrelevant to deciding the ultimate TRUE or FALSE state of the rung, the system will bypass (or in some way shorten the evaluation of) further conditions and jump right to output processing.
While this sounds efficient does anyone have a reference to an official technical publication which specifically states this behavior in the evaluation of rungs? (I'm thinking primarily Allen Bradley or AutomationDirect PLCs since those are the ones I'm most familiar with.) I'm looking not just for a recommendation of rung structure but an actual statement as to how this 'evaluation shortening' takes place.
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