Pulse Limitations with Online Change

At the first cycle, the pulse evaluation is ignored, and the memory is updated.

This memory enables the pulse evaluation from the second cycle.

When we apply the Online Change between t0 ant t1, the cases where this method is not correct are the two following:

Falling Edge

When we want to detect a falling edge:

Figure 1: Pulse Limitations with Falling Edge

Rising Edge

When we want to detect a rising edge:

Figure 2: Pulse Limitations with Rising Edge

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• If you want to avoid this limitation, you must use declared instances of R_TRIG and F_TRIG function blocks.