not able to write the data through DAQ

[dataacq]

hello,

          I actually need to send a code word(text file) generated from matlab program through my DAQ ( NI-USB-6215). my program(transmitter.vi[case structure: page2]) attached below has a problem in doing the task. when ever i run the program it give me an error message as

Error -200479 occurred at DAQmx Start Task.vi:2

Possible reason(s):

Measurements: Specified operation cannot be performed while the task is running.

Task Name: _unnamedTask<84>

At this time i can see no output in my oscilloscope. But, if i highlight my execution i can observe my samples on the oscilloscope with the following error message

Error -200288 occurred at DAQmx Write (Analog 1D DBL 1Chan NSamp).vi:3
Possible reason(s):

Measurements: Attempted to write a sample beyond the final sample generated. The generation has stopped, therefore the sample specified by the combination of position and offset will never be available.

[Bueller]

Hello dataacq,

I have modified page2 of your code, please take a look at it, andlet me know how it works.

Best Regards,

Faris

[dataacq]

Hi Faris,

               Guess you are using labview version 8.6. it gives me an error as it unables to load the vi(transmitter modified) as i am using a lower version 8.2.1.  Is there any alternative? 

thanks for the help.

regards,

raja

[devchander]

Here's Faris's VI in LabVIEW 8.2

Hope this helps

[dataacq]

thanks for the help dev.

[Bueller]

Sorry about the inconvenience.

Let me know if it works

Best Regards,

Faris

[dataacq]

Hello Faris,

                    Sorry for the delay in replying. I was out of town an not able to look at it. i just tried to run the vi. when i placed an indicator at DAQmx write vi for the number of samples written it is showing the total number of samples in the two columns(first column excluded). But my codeword contains more number of columns like the way in the attatched text file below. Also, could you please explain me the for loop you modified.

[Bueller · Accepted solution]

Hi Raja,

All what I did is I moved the " DAQmx Write" outside the while loop. What the VI is doing in this case is reading the file and passing it to an array, and then this array is being formatted a waveform to be written to the DAQ device.

As far as how the data is read, i didn't modify anything, it was based on your original code. A good way to know if you are writing the correct data is to check the graph display in the VI.

So the question is , is the graph display showing the correct waveform ?

Best regards,

Faris

[dataacq]

Hi Faris,

               The graph displays entire data, but, out of my DAQ only two columns of data are being sent.

[Bueller]

It would be nice to  connect the analog out ( the generated signal) to one of the analog in and check what is the signal that is really generated.

Let me knoe how it goes.

Best regards,

Faris