Mitsubishi FX PLC

[Goody]

...and P in ZCP (or any other instruction) means it's executed only
on first scan (pulse)

That is true panic - except in this instance. The P part is part of the CP instruction and is just part of the instruction.
You can put an extra P on ZCPP to make it a one shot.
Otherwise it compares every scan if the logic is true.

 

[panic mode]

fair enough...