error 200279

[RobertOne]

Hi, I'm Roberto and I'm a newbie of Labview; so, first of all, I want to apologize if my problem has already been solved, but I'm unable to find an answer.

I attach my VIs so you can see the problem directly. My Labview version is the 8.1.

In "potenziometro3" I have no problems, the VI runs properly. As you can see, there's only a while loop and everything is ok.

In "potenziometro2" I have to add a case structure, which slows down the acquisition and then I get the 200279 error.

Here it is the error:

Error -200279
Possible reason(s):

Attempted to read samples that are no longer available. The requested sample was previously available, but has since been overwritten.

Increasing the buffer size, reading the data more frequently, or specifying a fixed number of samples to read instead of reading all available samples might correct the problem.

Property: RelativeTo
Corresponding Value: Current Read Position
Property: Offset
Corresponding Value: 0

Task Name: _unnamedTask<AA

In this VI I'm acquiring data from a potentiometer with a PCI 6024E, then I have to manipulate them before giving them to the DAQ 2. All of those calculations represent an equation needing to be solved, and the case structure is necessary if I get a specific value from DAQ 1 which makes a denominator go to zero, cause in this case I can't use those calculations but I have to use another method, the one in the "false" window of the case structure, actually.

How can I avoid this problem of slowness?

I explained the whole situation to ask if there are other possible solutions to solve the problem, consisting for example in changing configuration and using something different from the case structure, something that may not slow down the program.

Thank you in advance, I'm waiting for your reply

[Eric_LV]

Hey Roberto,

It looks like in your case structure you are trying for the false case to write a constant DC value to the output channel.  You have done this by wiring a DBL data type to the output of the case structure.  Since the DBL you wired is a scalar value it means it only writes one value at a time, which is too slow for your analog output task.  You can avoid this by having the false case generate multiple points at a time.  I went ahead and changed the case so it will generate a constant DC signal at the value you specify.  You may find something like this will work better for you.  

[Eric_LV]

Whoops, put the wrong VI on the post,  try this one.  

[Cla_Cup]

Hi Roberto,

I agree with Eric. Did you try to run the VI he attached in his last post?

Best Regards

Claudio C.

NI ITALY

Applications Engineering Dept.

[RobertOne]

Dear sirs,

thank you for your interest in solving my problem, sadly I can't open the file cause I have labview 8.1 and the file is made with the newest version.

By the way I solved the problem using a "select" block of comparison which works quicker than the case structure, and I also managed with the options of the DAQ assistant, changing number and frequency of samples.

Luckily everything seems to be ok, at the moment!

Thank you again,

Roberto