pat.stave

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  1. Lowpass filter function block

    Lowpass filter for Omron PLCs.
    Only tested on CJ-series CPU. Use at own risk!
    Many thanks to Peter Nachtwey @ PLCS.net for providing the mathematical formula.
    Unfiltered = raw unfiltered value in INT.
    TC = Time constant tau, given in seconds.
    Filtered = Filtered value in INT.
    FilteredReal = Filtered value in REAL.
    - The FB can be duplicated.
    - The FB can only be used in program parts that are scanned every CPU cycle, as it relies on the "P_Scan_Time_Value" variable.
    According to the working principles of a lowpass filter, it will take the filtered value tau amount of seconds to reach 63% of the unfiltered value.
    The value will reach within 1% of the unfiltered value in approx 5x tau.

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