Generate signal from task DAQmx PXIe-4330

[BrunoAlfano]

Hi,

I'm trying to generate a timing source for a timed loop acquisition cycle.
I've got a PXIe-1082 chassis with a PXIe-4330 for strain gauges, a PXIe-4353 for thermocouples and a PXIe-6363 for pressure transducers.
I've already setup the acquisition cycles for the 4353 and 6363 with global channels and it works flawlessly; the same sequence generates this error for the 4330 when I try to generate the timing source:

"Error -200452 occurred at DAQmx Create Timing Source (Signal From Task).vi:4

Possible reason(s):

Specified property is not supported by the device or is not applicable to the task.

Property: SignalFromTask.Signal

Task Name: LC0:1"

Is it possible to generate a timing source for the 4330?
Thank you very much.

[Valerio.S]

Hi Bruno,

Some modules like for instance the PXIe-4330 does not support the timing source. It just depends on how they are made. For your timed loop you can use your other modules that you have and it will work just fine.

Have a good day,

Val.

[BrunoAlfano]

Thank you very much Val!
My aim was to minimize cpu load for I've read that when you execute the polling from the instrument in a while cycle it's executed each time until the DMA buffer is filled; timing source only calls it when the buffer is ready to be read.
I think I'll use the timing source for the other instruments while leaving a 100hz timed cycle for the 4330 so the polling isn't executed too often... data from 4330 isn't critical for the project and I only need to log and show it, so I can wait for it a little bit more.
Havve a nice day!

[Brad_K]

Hi Bruno,

To expand on Valerio's answer, the reason that the PXIe-4330 doesn't support the Sample Complete event is related to the fact that this module uses delta-sigma ADCs. The ADCs used on the PXIe-4330 have a digital filter group delay of up to 36 samples (see the module specs for a table of sample rate vs. group delay). When a sample is acquired, the data is not available until 36 sample periods later. If the sample complete event was supported on the PXIe-4330, it would be much less useful than on most other modules.

However, the PXIe-4330 does support the Every N Samples Acquired Into Buffer event. Perhaps you could use this instead? Note that the Sample Complete event executes after each sample is acquired, not only when the buffer has data to read, and it may execute before the data is transfered to the buffer.

Brad