Ni-USB 6259

[Rehmanymu]

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? 

[pipipi0405 · Accepted solution]

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.

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P8b1SAC&l=en-US

[Rehmanymu]

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. 

[pipipi0405]

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.

[Kevin_Price]

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