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LabView Plotting the Same Waveform Twice

Hi, I was using the Continuous Measurement and Logging Template (DAQmx) and I made some modifications for it to also read from a serial device.


Now for some reason, LabView is plotting the analog input data twice on the same waveform (See "Upstream Pressure" graph in attachment). Is there a way to remove this?


Much thanks,


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Message 1 of 6

I could not open your project because I'm using LV 2012. You can expand the graph legend and hide the red line, but I'm guessing there is a deeper problem with your code if you can't figure why it is plotting 2 lines instead of 1.

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Message 2 of 6

In the subVI where you create the notification, you are acquiring "N sampes,N Channels", Maybe you have it configured for 2 channels?

(sorry, I don't have DAQmx installed, so I cannot look at it in detail)

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Message 3 of 6

It seems like I created the same task twice. If I allow the user to select a DAQmx task created in MAX in the Settings dialog, is there really any purpose for Initialize Hardware

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Message 4 of 6

Congratulations -- this is one of the nicest pieces of code I've encountered on the Forum over the past several months.  Thank you for organizing it in a Project (although "Untitled Project 2" lacks imagination), and also thank you for including the entire Project.


You use the Hardware Configuration Cluster (kudos, as well, for TypeDef-ing all of your Clusters), so if you do not initialize it somewhere, you won't have a Task to reference!  However, since you are using LabVIEW Project, you might consider defining the Tasks inside the Project, rather than in MAX.  To do this, right-click "My Computer" in the Project Explorer, choose New, then New Task.  It will open a MAX-like window where you configure the Task.  This Task will appear as a Drop-down option on your Task Constant, using a slightly different Icon to distinguish it from a MAX-defined Task.


Hmm -- I just re-read your question.  What do you mean by "the Settings dialog"?  Was that something I missed?  [Probable answer -- yes, Bob, you missed it ...].


Bob Schor

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Message 5 of 6

Hi Bob,

Please see the attached screenshots. The first one is the Settings Dialog vi. It seems I can load the task I have defined there, or in Initialize Hardware


Currently my Settings is what is shown, and I have removed the "Task to Copy" input of DAQmx Create This seems to have removed the double plots.


Also I will definitely get around to defining Tasks in the Project if it is recommended.


Much thanks,




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