Thanks you Jack - and Visual-Q.
I am using this standard solution now :-)
But I don't understand why there is this extra-object 'Cycle' because
1/ we can customized 'x', 'y' by object in "vars parameters", without using cycle.
2/ this can lead to conflit between parameters (in your exemple, "1 sec" versus "i * 1 + 0.5")
3/ and why the name is 'Cycle' ? There are no repeating processes with it.
Anyway ! Thanks you again :)