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interaction niScope triggered acquisition synced with DAQmx

Hi,

Hardware Used:
I am using a NI PXI-5105 High speed digitizer, a NI PXI-6251 M-Series card in a NI PXI-1050 Chassis, that is connected to a PCI Express card via a NI PXI-8360 card. On the PC, I use LabVIEW 8.2 Extended Development Suite.

Task Description:
My task is the acquisition of ultrasonic soundwaves that occur 10 times per second and last about 40 micro-seconds. The amplitude changes about 3 orders of magnitude during acquisition. In addition to that I have 2 pressure-sensors and one flow-sensor connected to the system.

Main Problem:
I need to change the scope's vertical range while acquiring in order adapt to the change in amplitude. In thread
http://forums.ni.com/ni/board/message?board.id=170&message.id=44671&query.id=167091#M44671
it is described that the acquisition cannot be continuous to achieve that.
I need to sync between the pressure and ultrasonic signals.
How do I maintain comparable time-stamps between both cards while terminating the digitizer's session regularly? Is there even enough time between signals for the digitizer to rearm?
I got a continuous acquisition with both cards synced and triggered running.

Side Issue:
Is there any best practice for syncing niScope tasks with DAQmx tasks?

Thanks in advance for your answers.

Stephan Freyberger
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Hello Stephan,

You cannot change the scope's vertical range during an acquisition because the vertical range is configured before the acquisition starts.  Only fetch attributes may be modified while an acquisition is in progress. The example niScope EX Configured Acquisition.vi allows for the range to be modified during the execution of the VI because the acquisition session is configured, started, and completes over and over.

You can call the niScope Export Signal.vi to export the sample clock of the 5105 (note: you can only export the sample clock and not the timebase).  The DAQmx Timing Property Node would then be used to define the source of the master timebase of the M-Series board.

Regards,
WolfgangZ
 

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Hello,

thank you for the quick answer!

Do you have any idea of how fast/slow that configuring, starting and completing of a niScope acquisition is? Is it software-dependent? Is that timespan reproducible?

Concerning my "side issue" I ran into further problems. I used the niScope Export Signal.vi and exported the "Sample Clock" to "PXI Trigger Line 1/RTSI 1". The following error message pops up after stopping the task:

Error -1074118499 occurred at Error occurred at: NiScope Initiate Acquisition.vi:3

Possible reason(s):
Driver Status:  (Hex 0xBFFA409D)
Exporting decimated sample clock is not supported on this device.

Status Code: -214245

Now I wonder what it means.

Cheers from Aachen
SF


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