Dynamic Signal Acquisition

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virtual oscilloscope trigger

Hi,

I have a virtual oscilloscope build in lab windows v7.I have a high speed data acquistion card PCI-6025 having DMA and on board memory .The problem i am having is that the acquired signal is free running, and does not stand still  i understand that to make it still i should have some trigger.

could somebody help me on this

thankyou 

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Hey Matin,

E Series DAQ devices can be triggered with a digital signal or an analog signal (depending on which board you have).  The 6025 does not have analog triggering, but you can use a digital trigger (according to the E Series manual "The digital source can be any of the PFI or RTSI <0..6> signals.").  There's also another resource on ni.com that should help you understand the different types of digital triggers.  It's called Tips and Techniques in Data Acquisition Triggering - NI-DAQmx. Hopefully those resources will help you get on your way.  Of course some of the example programs show you how to set these types of triggers up.  If you're in LabVIEW, go to the Example Finder to find these (under Hardware Input and Output->DAQmx->Analog Measurements->Voltage). You'll see examples that end with "Dig Start" or "Dig Ref".  If you're not using LabVIEW, there are similar examples installed with DAQmx.  (i.e. if you're using C then search for a folder on your hdd called "DAQmx ANSI C")

 

Have fun with triggering!!

 

-gaving

 

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hello gaving,

Thankyou for the reply.I am using the MeasuringComputing board PCI-DAS 6025, and oscilloscope is built in  Lab windows.

I have gone through the articles you suggested, but could not understand how to use the digital trigger to get my waveform stable on the screen.

It keeps on moving

Do  i have to change the trigger frequency when i change the time/DIv on the scope.

what can I do to get the waveform stable as in real desk top oscilloscope.

thankyou

matin 

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matin wrote:
...the MeasuringComputing board PCI-DAS 6025,

Wow, was I wrong Smiley Very Happy

Oh well, I thought you were using the PCI-6025E from National Instruments.  I guess I assumed, and that...well...you know.  I'm not familiar with their driver or applications built in LabWindows.  You are more than welcome to see if someone on this forum can answer your question  ANY Measurement Computing GURUS out there?????or you can call their tech support

Message Edited by gaving on 08-27-2009 10:03 AM
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