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Old February 5th, 2018, 04:12 PM   #16
Steve Bailey
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Join Date: Apr 2002
Location: The boondocks of Western Massachusetts USA
Posts: 6,767
The value of 89 is the correct result of subtracting negative 28554 from negative 28465. If the screen capture was of the scan that caused the underflow, neither of the one-shots were true in that scan since the value of S:42 was zero. Unless something in ladder logic wrote zero to S:42 between those rungs and the end of the program.
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