Chapter 4 Relay Ladder Logic Programming 48
Pulse Output Instruction (Flip-Flop) ( P )
A pulse output instruction, or Flip-Flop, turns ON a coil (Q) or an auxiliary contact (M) when the
preceding input contact transitions from OFF to ON. Once the output is ON, it will remain ON until
the preceding input contact transitions from OFF to ON a second time. In the example below, When
Pushbutton I3 is pressed and released Motor Q4 will turn ON and remain on. When Pushbutton I3
is pressed again, Motor Q4 will turn OFF and remain OFF. The pulse output instruction (P) will “flip-
flop” its state from ON to OFF at each press of Pushbutton I3.
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