I have a USB 6003 card and want to set up a triggered AO. I know you can start a pre-defined AO waveform using the PFI lines (in my case 100 step sawtooth from 0-2V) and I can get this to work. However, I cannot get it to step through the AO levels where each sequential trigger to the PFI line increments the voltage by 1 step, it seems to always step through the voltages at a fixed sample rate. I have successfully achieved this triggered stepping on another USB DAQ card so is this a limitation of the USB 6003? The documentation for the 6003 is quite unclear about what you can actually do with the PFI lines.
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To do what you want, you should configure the task to use the PFI signal as a *sample clock* rather than as a trigger. You can do this with your call to DAQmx Timing.
Thanks for replying. I have attempted this already but it still just scans through the voltages at the rate set by the rate in the diagram below. Here the array is just a 1D array of voltage values to scan through
I'm dubious. Check again.
If your 'Clock line' is a PFI terminal fed by some external clock source, your *actual* AO update rate will follow that clock rate *regardless* of the value you happen to wire to the 'rate' input of DAQmx Timing.
Try it. For the same frequency external clock signal, try wiring in a value like 20000 as the rate, then try wiring in a 2. It won't have any effect on the actual AO sample rate.
For anyone who searches for this looking for an answer, the USB 6003 doesn't allow external sample clocking only triggering the start of the AO function. It will default to the rate set in the sample clock
Thanks for the followup and sorry for steering you wrong -- I didn't know the USB-6003 had that limitation.