Dual Output for Swept Sine Wave

[arwong]

I am using the Swept Sine Wave functions in the Sound and Vibration Toolkit. When I configure the swept sine wave using the Initialize Swept Sine VI,it only asks for one excitation (analog out) channel. For what I'm doing I need two excitation channels that are 180 degrees out of phase. Simply put,I need to figure out how to take what the swept sine function is outputting to the analog output and multiply that by -1 and send it to a second analog out. One way of doing this would be to wire an inverting op-amp to the analog output, but I'd rather do this through the software. Does anyone have any ideas on how I could do this?

[dsb@NI]

Can you help me understand your application a little better? What are you testing where a second excitation channel (180 deg out of phase with the first) is required? Does this mean that you would also need two additional inputs that would use the second excitation channel as a reference?

[arwong]

I am testing an actuator which requires two out of phase input voltages to operate. Since the command voltages to the actuator are exactly 180 degrees out of phase I can just pick one of the voltages to use for the stimulus channel. The two excitation channels will only produce one response. Does that make sense?

[dsb@NI]

I have a couple of additional questions for you, and I can certainly help you to modify the swept sine so to implement dual outputs. If you are still interested in dual outputs for swept sine, email me at doug.bendele@ni.com