Unstable Analog Output from USB6001

[Naomi0649]

Hi,

I was trying to use Labview to generate an analog output in sawtooth shape through USB6001. When I measure the output with an oscilloscope, however, the frequency of the output signal is not stable. 

Shown in the picture attached is the Labview program I used. I'm wondering if it is some problem in my Labview or the USB6001 that leads to such frequency oscillation.

Thank you!

[pipipi0405 · Accepted solution]

In order to stabilize output signal, you need to use hardware-timed analog output. You currently have your DAQ set to output signal in software timing, which is the reason why your output signal frequency is not stable. 

You should refer to Hardware timed Analog Output example VI. 

However, USB-6001 has maximum output rate of 5kHz. If you need to generate signal in higher frequency, you need a more expensive DAQ.