Yaskawa MotionWorks IEC - Manual (Page 20)

PLCopenPlus Function Blocks for Motion Control 2013-04-13 12
The behavior of the “Execute” / “Done” style FBs is as follows:
Why the command input is edge sensitive
The “Execute” input always triggers the function with its rising edge. New
input values may be commanded during execution of a previous command
because the inputs are only read once. The 'Done' output can be used to
trigger the next part of the movement. The example given below is
intended to explain the behavior of the Function Block execution.