Hi speed non-regen AO with LV DAQ Occurrences

[Spaz]

Hi

I need to output 6 non-repeating patterns to 3 PCI-6111's @ 150kHz.

Can anyone explain to me why the attached LV7 Development Library example, with modified defaults and utilizing DAQ occurrences, will not work when more than one copy is run? When I try to run a second copy (with the device number different) the first copy produces a -10803 error.

Another example (also attached) will successfully allow 3 copies to run simultaneously. While it can get the job done, I was wanting to use the DAQ occurences, because I thought that would allow the minimum amount of CPU usage. This is the first time I've had to do anything more with AO than state levels. Am I missing something basic here?

Thanx.

[Erick]

Hi,

I believe what is happening is that your first VI is using DAQ occurrences and locking the driver. This is because traditional NI-DAQ (before DAQmx) is single threaded meaning it can only execute one DAQ process at once. When you try to start another VI with occurrences it times out (error -10803) because it cannot access the part of the driver that does occurrences.

Since DAQmx is multi-threaded it is able to run multiple VI's and can actually trigger on multiple boards. DAQmx will support the PCI-6111 in NI-DAQ version 7.2. Until this is released I would suggest using continuous generation without occurrences when using multiple boards.

[Spaz]

Thank you for your time, the information and the heads up on NI-DAQ 7.2