The OSF, also known as One Shot Falling, instruction allows a programmer to create a scenario where an output is energized for a single scan when a transition from a logic HIGH to a logic LOW is detected on the input side of the instruction. The instruction allows an experienced programmer to capture key components based on such a transition and allow a one-time execution of particular bits of logic. This instruction can be found on the right side of a ladder logic rung and has two bits tied into it. One of these bits, labeled as “Output Bit”, can be used elsewhere in the code to energize other instructions when the OSF is enabled.
This is a companion discussion topic for the original entry at https://www.solisplc.com/tutorials/plc-programming-fundamentals-osf-one-shot-falling-instruction