Error -200284 when trying to build digital oscilloscope

[pineapple77]

I'm trying to build a virtual oscilloscope where my DAQ (6001) is connected to a function generator, but I'm getting the following error: -200284 

Oscilloscope.vi:Instance:5:530001<append>
<B>Property: </B>RelativeTo
<B>Corresponding Value: </B>Current Read Position
<B>Property: </B>Offset
<B>Corresponding Value: </B>0

<B>Task Name: </B>_unnamedTask<9BD3D>

I've attached my vi. Any ideas to fix this would be greatly appreciated.

[Bob_Schor]

I'm guessing that you are a relative "beginner" in learning LabVIEW.  You do not seem to understand the principles of data acquisition, the notion that to acquire continuous data, you need to do continuous sampling.  To use an oscilloscope (digital or analog) to visualize such continuous data, you need to do continuous visualization.  Finally, to simultaneously do two continuous tasks, one acquiring data (continuously) and another simultaneously visualizing these continuously-acquired data, you need to have two tasks (Acquisition and Visualization) happening in parallel.

Fortunately, as you learned when your Instructor explained the Principles of Data Flow, LabVIEW is inherently capable of such parallel tasks.  You have one loop that continously acquires data, and hands the data to another loop that continuously displays it in a Graph.

Of course, to do this, you need to wean yourself from the Dreaded DAQ Assistant (DDA), an "Express VI" developed by NI to convince LabVIEW beginners that they don't need to understand the Principles of Data Flow, and can take "shortcuts" and design their own Digital Oscilloscope without knowing anything about Digital Data Acquisition.

Here's a question -- did you look up what Error -200284 means?  Open LabVIEW, find "Help" on the top Tool Bar, and click "Explain Error.  Enter -200284 (don't forget the minus sign) and read the explanation.  

Now do a Web Search for "Learn 10 Functions in NI-DAQmx and Handle 80 Percent of your Data Acquisition Applications" (or a title close to that).  Ignore the first step (the DDA), and see how to acquire data continuously.  You are probably about a month or two from learning enough LabVIEW to get anything like a Digital Oscilloscope (unless someone "does it for you"), but if you keep learning, keep programming, and really try to Learn LabVIEW, you'll get closer ...

Bob Schor

[pineapple77]

Thank you for your response but for my assignment I am required to use the DAQ Assistant. If it helps the program does work correctly when triggering is off. It is only when I attempt to apply a digital edge trigger do I get the error. If you have any suggestions that would be most appreciated.

[Bob_Schor]

I'm sorry my attempt to help you clashes with that of your Instructor.  I have nothing more to add to my previous response.

Bob Schor