You can configure a pulse which fires at random intervals within theStimulator Waveform Customizationpanel. Access theStimulatorfrom the Setup menu and click theCustomizebutton.
In theSegment parametersfor a pulse segment, type the functionrandominto the End Delay value box. Therandomfunction will provide a value between 0 and 1. You can also include further arithmetic to change the randomization limits; for example, multiplying by 0.5 will randomize values between 0 and 0.5.