waveform chart

[Identcor]

Hi,

I'm acquiring a 10 Hz senoidal signal and my sample rate is 250 Hz. I'm sending (serial port) it (a sample at a time) to another PC as fast as it could be. My apps TranWave and RecWaveChart are in attchment. When I run this two vi's together I can see in the RecWaveChart waveform Graph a number of cycles of the 10Hz senoidal signal corresponding to the number of samples of 4 ms (250Hz). This is is an example I´ve just run: 20 cycles of 10Hz signal in aproximately 500 samples in waveform Graph (equal to 2s)  This is ok but I don´t know what I have to do to my waveform Chart XScale shows the actual time, the time in chart Xscale run faster than the actual time, it starts at the correct time and I can see 10 cycles of the senoidal signal in 1 second of the chart (10Hz as it is), so the multiplier is ok, but the XScale is incremented faster than the actual time and when vi is interrupted the time in XScale is much more later than the actual time. Why it runs faster?

If you run the Real-Time Chart example putting delay time near 0 you will see that the time is not the actual time too, it starts correct but then it runs faster. That is what it is happening to me and I don't know what is wrong.

Another problem in the waveform Chart is the history, if the the number of samples doesn't reach the history length set, the waveform in chart is repeated several times and I´m already clearing the history Chart before the while loop.

 

If anyone could help me I would thank you

Celia

[Filipe Silva]

Hi Célia,

If i understood it well, its happening, as you said, because of the velocity of the processor. Its running faster as it could be, so the time will appear the most faster it could.

Maybe, if you try to time the vi it will appear correctily.

Let us know the application status.

Regards,

Filipe Silva