The "Measure program runtime" instruction is used to measure the runtime of the entire program, individual blocks or command sequences.

You should put it in the begin of OB1 and it will return OB1_PREV_CYCLE as LREAL value in seconds.

On this base you can make very presiсe timers or what ever you need.

I use it to set each second or 0.1 second bit for one OB1 cycle, this bit is used in many my functions. Simply add 1 to some delay timers.