Two synshronized Analog Inputs

[SKNI]

Hi,

I am using PCI-4461 and connecting two amplifiers into its Analog Inputs (AI0 and AI1).

I need the output voltage of two devices versus time together; this means that AI0 and AI1 must be synshronized.

And then plot the Voltage v/s Time in 2 different plots; this means that I need to split the signals and analyze each channel separately.

Number of Samples : 200 000 Samples

Do you have any idea how to do it ?

I used the channel expansion on the DAQ PCI-4461 to select multiple channels and by holding down on control, I selected multiple channels.

How to continue to get the plots ?

Thank you in advance,

Kind regards,

[Dennis_Knutson]

You have not mentioned the type of DAQmx Read you are using (2D DBL, 1D Waveform) but in either case, you use an Index Array function. If you are using the DAQ Assisant, then just use the Split Signal function.

[SKNI]

Thank you for your answer Dennis_Knutson,

After reading the "DAQmx Read VI", I think that I need Analog 1D Wfm NChan NSamp because I am reading multiple AI virtual channel and return data as waveforms.

I am beginner with Labview, and I noticed that the DAQ assistant is very useful. However, I don't know how to replace it in my block diagram. Please see attachment. Do you have any idea ?

Thank you !

[Dennis_Knutson]

I do not use the DAQ Assistant and I don't believe most experienced programmers use it much either. It can be slower than the lower level DAQmx functions and can offer less options. It also uses the absolutely evil dynamic data which your image shows you using by the use of the split signal function. As I mentioned, you just need an Index Array function to separate the channels.

That being said, to use the DAQ Assistant, you replace all of the existing code with a DAQ Assistant inside a while loop. I don't see the point in using it however since the code you have looks fine with the exception of the split signal.

[SKNI]

Thank you for saying that. Then, I will not use the DAQ Assistant.

Where and how do I need to connect the Index Array function ? (It is a little bit difficult to understand how this index array function works)

After that, the Index Array function will replace the job of the Split signal in my block diagram, right ? so I can remove it.

Another question : Do you have any idea how can I divide my voltage waveforms by a constant value ?

Thank you !

[Dennis_Knutson · Accepted solution]

Connect the 1D waveform array to the Index Array input. Drag it down to get two outputs. Wire each output to a graph. The index inputs automatically start at 0 so you don't need to wire anything there.

Dividing is done with the Division function. You just wire the waveform into one input and wire a constant to the other.

[SKNI]

Amazing ! It is working !

Thank you very much !

[SKNI]

Do you have any idea how can I divide my voltage waveforms by a constant value (for example '200') and plot the result in another waveform ?

Thank you !

[Dennis_Knutson]

Did you try what I said about the division function?

[SKNI]

Yes ! It is working now !

I was on the wrong constant... 'Beginner'. I am sorry.

Thank you !