How to modify Sine Pattern or Wave VI so that an offset can be applied to it.

[msmartei]

Hello,

Is it possible to modify a the Sine pattern.vi or sine wave.VI so that a voltage offset can be applied to them? 

If not, any ideas on how to build a VI that outputs an array with a sinusoidal pattern which can then be written to a channel?

Suggestions for other options are definitely welcome.

Thanks!

[MikeS81 · Accepted solution]

Hi msmartei,

you can use an "add" function on the array output. Connect the array output to one input and a constant with your offset value to the other input.

Mike

[Cory_K]

Look here:
Programming >> Waveform >> Analog Waveform >> Waveform Generation >> Sine Waveform.vi

You can specify frequency, amplitude, phase, and offset however you would like.

As for how to write to a channel:
Measurement I/O >> DAQmx Data Aquistion

Those functions should help you do anything you could possibly want to do with DAQ.

[msmartei]

 Thanks. Adding the offset worked to an extent but let me modify my question a little bit. I want to be able to have the sine wave oscillate about non-zero values since im writing the voltage to a device with a range of 0 - 10V. 

In other words, i want to shift my sine wave such that the center line is not zero and the minimum value allowed would be zero. 

Any suggestions?

Thanks,

msmartei

[MikeS81]

Hi msmartei,

can you show a graph of the result you want?

Mike

[Cory_K]

That is simple enough.

Just think of it from a mathmatical point of view. If you have:

y = sin(x)

and you want to 'offset' the y-value, then you just:

y = sin(x) + 'offset'

I added a constant of 5, but you can change that to a numeric control if you want

[msmartei]

The problem is that my offset is not constant: It depends on the
initial values at the piezos, which could be values as small as zero.
So in a case like this, the sine wave is still centered about zero.

With some arithmetic manipulation, i figured it out:

Sine plot= (abs(Vi-Vf)/2) (sin x) + (abs(Vi-Vf)/2) + Vi

This ensures that the sine plot is always between Vi and Vf .

Thanks for all the suggestions!

- msmartei