how to manululate the output of the DAq Read

[Shake]

hi ...

Iam using kusb3116 DAQ for plotting the data on to a graph ...

i have used the LV-Link VI's to collect the data from two channels of the DAQ on to the PC ..but now i need to plot the waveform chart ..for the two voltages ...
My problem is how can i manupulate the data that i have captured from the DAQ before i plot it on th graph, as i need to manupulate one of the voltages ..before actually plotting ..

Thnks,
Shaik.

[Dennis_Knutson]

It would be nice if you explained what kind of 'manipulation' you want to do. You should be able to use just about any of the math or signal processing functions that are in LabVIEW. What have you tried and what kind of problems are you having?

[Shake]

Hi ..
Thanks for the Reply .. i have sloved that issue ..
Currently iam facing an other problem...
As iam invoice labview programmer ..i am using a k3116 DAQ .. using that iam capturing a signal at a sampling rate of 500kSamples/Sec and plotting that on to a waveform chart ..
To be more specific ..iam capturing a square wave ..which has varying amplitudes ..and i want to know how can i calculate the amplitudes(Voltage)  when the wave is in ON position and viceversa OFF..

Thanks
Shaik

[Dennis_Knutson]

You could simply use Array Max & Min or on the Signal Processing>Waveform Measurements palette is Amplitude and Levels. This returns the high level state and the low level state. There's also the Express VI called Amplitude and Level Measurements.

[Shake]

Hey Thanks Dennis...
it works Fine ...

May i know how can i calculate the Duty cycle of a square waveform ..that i have captured using the kUSB-3116  DAQ..

Thanks.

[Dennis_Knutson]

I don't know which technique you used but there are two different functions that will do this and both are adjacent on the palettes of two of the functions I mentioned above. What I would suggest is that you always have the context help open (on the help menu). When you do this, a little help window will appear when you move your mouse over a function on the palette.

I'm not giving you the direct answer because I think it's important that you learn for yourself what basic functions are available in LabVIEW.

[Shake]

i got it ..
Is there any data type converssion tht i can perform to convert a 2D array of 16 bit floats in to a waveform DBL,...

Thanks

[Dennis_Knutson]

Sure. If your 2D data is arranged so that each column is a channel, then do what's shown below. The Build Waveform function is on the Waveform palette. If you data is arranged so that each row is a channel, don't use the Transpose 2D Array. You are not using an NI DAQ board so I have no idea how it returns data.

Message Edited by Dennis Knutson on 03-15-2008 08:26 AM

[Shake]

FRom the KUSB-3116 DAQ iam Getting the data as..

(Data Value contains a two-dimensional array of 64-bit, floating-point values. Each element in the first dimension of the array corresponds to a channel in the task. Each element in the second dimension of the array corresponds to a sample from the channel.)

Hi dennis ..
i dint understand abt the dt input that was shown above... Since iam reading 500Ksamples/Sec .. what should this input be for my case ...

Thanks,
Anwar

[Dennis_Knutson]

I'm not sure if their exaplanation is much help. You should be able to determine whether the channels is in columns or rows simply by creating an array indicator.

The dt is the inverse of the sample rate. 500Ksample/sec means that the time between samples is 1/500K = 0.000002.