Multifunction DAQ

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Using wfm_from_disk to output to multiple channels

I have three raw data files I need to output on three individual channels of a 6713 card... I'm having no problem outputting a single channel, but I have a few questions about combining the three files and using the WFM_from_Disk in VisualC++ or Visual Basic. Would it be correct to assume the file should be structured with alternating samples from each of the three source files?

Also, the WFM_from_Disk function is choking when I set the numChans parameter to anything larger than one. I've tried many combinations of values for the chanVect array without success. The function usually returns a invaildValueError (-10003). There also seems to be some relation to file size, but I can't find a definite pattern... I've
tried file sizes anywhere from 6 bytes to 900000. Where do I look next? Is there a better way to output my data?

Thank you,
Jaime Kopchinski
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One option you may want to consider is to use the normal file I/O operations in Visual Basic to store the data from the file into a buffer. Then you can use the normail WFM operations instead of the WFM_From_Disk. There are several example programs that are installed with NI-DAQ that demonstrates how to use the other WFM functions. Let me know if you have any questions about using the normal WFM functions.

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