Ni-DAQ Multiple Waveform Question

[RCBrust]

I'm new to LabView so hopefully I'm using the correct terminology.  I've used DAQ Assistant to create a DAQ Assistant Express VI which reads 2 channels from my NI hardware, voltage and current.  This seems to function well in that I can graph the captured waveforms and also write them to a file.  The problem I'm having is that the waveform output has the two signals embedded together and I can't find a way to access them separately.  For example, if I create a graph it graphs both voltage and current.  I can't create one graph to display just voltage and a second to display just current.  Another example is when I try to move the waveform into an array.  The function block works fine in that I can display the array and step through the data, but it will only give me the voltage data with no access to the current data.  Any help would be appreciated.

Thanks,

Randy

[StevenA]

the daq assistant returns data using the dynamic data type.  I would convert the dynamic data type to an array of waveforms.  Then you can index the first element (channel) and put in on one graph, index the second element and put it on another graph.

The convert from dynamic data function is under the express pallet > signal manipulation

Message Edited by StevenA on 08-15-2008 09:18 AM

[Cory_K]

I would suggest using the "Split Signal" function

It is located:

Express >> Signal Manip >> Split Signal

Wire the output of your DAQ assistant to the split singal.

Then the two outputs of that function will be voltage, and current.

Then you can do whatever you want with each one.

[StevenA]

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Cory K wrote:

I would suggest using the "Split Signal" function

It is located:

Express >> Signal Manip >> Split Signal

Wire the output of your DAQ assistant to the split singal.

Then the two outputs of that function will be voltage, and current.

Then you can do whatever you want with each one.

---

Split signal works too

[RCBrust]

Hmm, I did happen to find the Split Signal function and tried it but it didn't seem to work.  Trying it again now...

Thanks guys.

Randy

[Cory_K]

What is not working?

Graphing the data?

Or splitting the signals?

[RCBrust]

Ok, if I add a Split Signal function, I can right click on the top output and I get the option of adding a graph which I do and I get my voltage waveform alone, which is what I'm looking for.  But when I right click on the next output, it seems to have no waveform associated with it.

Randy

[StevenA]

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RCBrust wrote:

Ok, if I add a Split Signal function, I can right click on the top output and I get the option of adding a graph which I do and I get my voltage waveform alone, which is what I'm looking for.  But when I right click on the next output, it seems to have no waveform associated with it.

Randy

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I'm seeing the same thing with the split signals...this should work, I'm not sure why?  Using my method where you convert to waveform data type will work. 

[RCBrust]

Got it to work another way.  I found the Select Signals function.  I put it in twice.  On one I selected voltage and the other selected current.  Works perfectly.  Thanks for the help.

Randy