Multifunction DAQ

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Ni-USB 6259

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Hello all,

I am trying to read two AI (Analog Input) from DAQ NI-USB 6253 simultaneously. It always shows an error. could anyone share code how I can read and synchronization? 

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Message 1 of 5
Accepted by topic author Rehmanymu

What error are you getting? If you are using USB-6259, it multiplexes the input so it is not exactly simultaneous.

If you are using a DAQmx API, you should just do what it says below.

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Message 2 of 5

Thank you.  It is very useful.   Let me explain to you more. MY device is NI USB-6259(BNC).  I am trying to read two XY piezo stage AI(Analog Input) signal and one AI from detectors through lock-in amplifier. My goal is to read and synchronize these three signal. Now I did by DAQ assistance through Explorer It is working. But It cannot show simultaneously. and did not show any error. 

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Message 3 of 5

You should use hardware that supports simultaneous analog input such as USB-6353 or NI 9215 when you want to acquire simultaneously, especially when you want to analyze data from a lock-in amplifier. 

That being said, if you could attach a screen capture of VI, I could take a closer look.

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Message 4 of 5

I suspect you're trying to run 3 distinct AI tasks simultaneously.  Instead you should include all 3 AI channels in 1 task.  There's only 1 timing engine available for AI, so you can't run separate tasks at the same time.


As stated before, those channels will be multiplexed and have a small fixed timing offset for when their A/D conversions are captured.   If you sample at 1 kHz,  all 3 channels will be updated every 1 msec.  But for each msec interval, the individual channels will be converted at a different offset within that msec.  These offsets *will* be hardware-timed and consistent.  


There are apps where it's ok to ignore this offset, apps where it's sufficient to know about it and compensate appropriately, and apps where you must use a device capable of true simultaneous sampling.  Dunno which kind you have.



-Kevin P

CAUTION! New LabVIEW adopters -- it's too late for me, but you *can* save yourself. The new subscription policy for LabVIEW puts NI's hand in your wallet for the rest of your working life. Are you sure you're *that* dedicated to LabVIEW? (Summary of my reasons in this post, part of a voluminous thread of mostly complaints starting here).
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