thanks for the reply,
i see all the exemple of fgen in labview, and finaly i use the Fgen Switch between Waveforms.vi exemple with some modification in the script and ofcourse i remove the part of software trigger.
now i can generate my sequence with external trig.
the script:
script SwitchWaveforms
wait until scriptTrigger1
repeat until scriptTrigger0
generate Waveform1
end repeat
repeat N // ( N times )
generate Waveform2
end repeat
repeat until scriptTrigger2
generate Waveform1
end repeat
end script