multichannel acqisition

[saeedkd]

Dear all

I am using a PXIe-5171R oscilloscope for a data acq. application. I need the streams from  all  8 analog input channels where one these 8 channels has to be used as my external analog trigger source (I use channel 0) . The problem I currently face is that with the use of the code I've attached to this post, I can acquire a finite number of samples from all channels or I have the option to acquire infinitely so long as the memory isn't full. When the latter happens,  the acquisition process doesn't distinguish between post-triggered and pre-triggered  data, therefore they are all included in the samples also, I ca not determine for howmany trigger pulses I want the acq. to be performed.  I have tried to fix this problem with the DAQmx functions but this particular device (5171R) is not supported by DAQmx. I would really appreciated if someone can kindly help with a modification to the code that allows me to acquire data in continuous fashion only after a certain threshold in the trigger signal is achieved and also to be able to determine for how many trigger pulses the acq should run . Thank you in advance. All ideas are welcome.