NI PXI 6221 DIGITAL I/O Generation of 10 digital signals and a clock signal on board

[ravi shankar]

Hi john

from your previous post I was looking for

the Analog Input Sample Clock, which initiates an acquisition for each channel in the task. Is this an external sample clock that I have to provide. Can you please let me know the pin which I have to use for supplying the clock. Because the DAC I want to test my DAC at 100 Hz.

Can you please explain me the inputs and outputs of this AI Counter DO Synch_LV80.vi 55 KB program clearly.. I cant vary the frequency in this example.

[John_P1]

Hi Ravi,

The Sample clock is being generated internally by the 6221 in my example as I had assumed you were intending to use the 6221 as your clock source. 

To use an external sample clock, just wire up the Source input to the DAQmx Timing VI in the voltage task.  You can also delete the Export Signal VI since you won't need to re-export the sample clock.  The delay from Sample Clock property should still be valid with an external clock.

Best Regards,

[ravi shankar]

Hi john,

I tried applying an external clock signal on PF14 and obtained the output signals but now I am missing the 10th bit i.e. I am having only 10 signals instead of 11 different signals. I actually need 11 different signals one clock source and 10 digital input signals. Say 1 Clock frequency of F1, D0=F1/2, D1=F1/4, D2=F1/8.......... D9=F1/512............ 

When I tried external clock on the DAQ I get the same external frequency on D0 so there is no difference.

I used external clock because I need to operate my device as low as 100Hz which the internal sample clock cannot generate when I tried lowering the frequency.