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We appreciate your patience as we improve our online experience.
01-28-2019 10:32 PM - edited 01-28-2019 10:33 PM
Hi All! I have a very specific question about data processing.
I am currently trying to use multiple channels and measure them "simultaenously" (I know the machine doesn't actually do that). I have an initialisation (see attachment) that includes three AI ports and also a write data section (see attachment) that runs , writes/reads, and then stops the process.
Now this is where I had problems understanding how the data is being read out, and so I know I am sure I am not aware of something.
When I select in the DAQmx Read I then select Analog > Multiple Channels > Multiple Samples > 2D DBL what exactly am I selecting? I expected three rows (From the three initialisations in the beginning) as an output but there are only two. So there is something I fundamentally missed. My purpose is to write finite data out from all the three ports using the DAQmx Read.
So far all the readout I get from two of the ports give slightly the same signal, as I understand there is also "ghosting" happening ( a separate issue I believe I have resolved by adding the third channel before the channel with lower impedance).
Note: I have looked at the following links quite a few times but if I missed anything that is relevant to this discussion please excuse my lack of observation. These ones were helpful so far but I just can't seem to find what I need to understand what is happening.
https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P8b1SAC&l=en-AU
http://www.ni.com/product-documentation/2835/en/
Solved! Go to Solution.
01-29-2019 04:54 AM
Nothing jumps out as wrong. You've configured your AI task to have 3 channels in it and when you call DAQmx Read (NChan NSamp), you should get a 2D array with 3 rows (one for each channel).
Not sure how new you are to this stuff, but is it possible that you're displaying the data in a GUI array indicator that only *shows* 2 of the 3 rows of data at a time?
-Kevin P
01-29-2019 05:06 PM
Thanks @Kevin_Price ! It seems that I missed it when I was busy writing up my imaginary problem 😛 Thanks heaps. Appreciate the quick help!
01-31-2019 11:40 PM
I am trying to generate the signals through labview and access these signals using DAQ. I have attached the code and obtained results below. Why the signals are looking like that in oscilloscope. how to correct it?
01-31-2019 11:51 PM
HI ashwini11 as I am a new member I do not have much experience. After taking a look at your code I am not sure what to say. It will be better for you to start a new thread and explain your problem in detail.
I have not worked with NIElvis so I definitely can help there.