$IF ONCE
When the condition is fulfilled the first time, the instruction section is executed once. The instruction section is no longer executed in later run-throughs, even if the condition is fulfilled.
Programming Example
$IF ONCE
; Define real-time cycle
#RT CYCLE [SCOPE = PROG]
; Query ACS position of X axis
$IF ONCE V.RTA.ACS.ACT_POS.X > 200
; Output M function
M100
$ENDIF
#RT CYCLE END