DAQmx multi taks meassurement

Refering to the LV 7.0 example ContAcq&Graph Votage Ext-clk Dig Start(file attached), in the generated waveform array the �dt� value does not change if you change the frequency in the Dig Start signal. The value of dt seems to be rather a random value.
How can I get, additionally to the AI-voltages (i.e. at the same time) the real dt of my signal?
Can my DAQ device 6034E read both signals at the same time (two tasks)?
Thanks a lot.
Attachments:
Cont_Acq&Graph_Voltage-Ext_Clk-Dig_Start_1.vi ‏109 KB

Hello Grivilla,
you´re right,
the value of the dt is sometimes incorrect if you use external sample clock.
In your example you set the maximum expected sample rate you want to use to the configure sample clock vi (sample rate).
If this value matches your real sample clock, your dt in the waveform is right.
On the other hand, if you set this sample rate to 1 kHz and your connected signal have only 995 Hz, you´ll get an incorrect dt value in the waveform (0,001 instead of 1/995...).
1.) Make sure that the sample rate you set matches the real sample clock you connect external.
2.) Measure the frequency of your sample clock and give this value (1/sample clock) as dt to your waveform.
For a simple example of it, use the DAQ assistant for creating a "measure F
requency" task.
You can run the AI and the frequency measurement in parallel.
Regards
Stefan K
NI Germany
SRQ 196177

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