Trying change duty cycle in "Simulate Signal"

Hi, 
Anyone knows why I can't change the duty cycle in Simulate Signal? This option appears unavailable for me. How I can access this option? I need generate a wave triangular assymmetric. 
Thanks.
Attachments:
simulate signal.JPG ‏66 KB

The dutiy cycle is only for square waves, i.e. a signal that only has two possible states (on or off). The duty cycle defines the percentage of the time the signal is on during each interval.
In any of the other signal shapes, the amplitude is variable and the concept of a "duty cycle" makes no sense.. 
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