The frequency is different between oscilloscope in real life and VI settings

[Camus_H]

I use the labview's waveform function to produce the waveform and set the frequency, also using NI compactRIO 9263 to output the waveform
Use connected oscilloscope in real life to the NI 9263 ,found  the frequency and duty ratio on the oscilloscope and in the VI
Change a lot of parameters is also wrong .What's the reason for this. Thanks a lot for your response

[IanSh]

You have no timing in your loop, so it is outputting the data as fast as it can. I suggest using a timed loop instead of a while loop. Then set the period of the loop to the sample period you want.

However, if your sample rate is higher than 1kHz, you can't do it in scan mode anyway, and will have to program the FPGA.

Incidentally, you don't need to regenerate the waveform every time you run it in the loop, you can put that code outside the loop to make things clearer.

[GerdW]

Hi camus,

and what about the first 225 iterations of the loop when you try to index non-existing array elements?

(You can solve this issue by prepending 225 zeros infront of the waveform…)

[crossrulz]

You are not going to get a good waveform in Scan Mode in a cRIO.  You need to program the FPGA.  Luckily, there is a good Sine Wave Generator in FPGA that you can use.  For something simple like this, you can get away with using the front panel interface on the FPGA.