LTON

VAR_INPUT

VAR_INPUT
    IN : BOOL; (*starts imter with rising edge, resets timer with falling edge*)
    PT : LTIME; (*time to pass before Q is set.*)
END_VAR

VAR_OUTPUT

VAR_OUTPUT
    Q  : BOOL; (*is TRUE, PT seconds after IN had a rising edge*)
    ET : LTIME (*elapsed time since rising edge at IN*)
END_VAR

If IN is FALSE, the outputs are FALSE or 0. As soon as IN becomes TRUE, the time is incremented in nanoseconds in ET, until the value reaches PT. The value then remains constant. Q is TRUE, if IN = TRUE and ET = PT. Otherwise Q = FALSE. Q thus has a rising edge, once the time specified in nanoseconds in PT has elapsed.
Graph showing LTON over time:

Requirements