Testing a USB device

[crys]

Hi,

I am Christiane and this is my first time posting a question. I am not really sure how everything works. Also, I am very new with labview and testing boards. Therefore, I would probably not be able to specify exactly what device I have.

I am trying to test a USB device with Labview and an oscilloscope by sending 5 bytes to the board in binary. When I connect the board to my computer and run labview, everything seems to work. I do not get any error. However, when I connect my board with a coaxial cable to my oscilloscope, I am supposed to get square waves but do not get any. At some point, I was able to get a single pulse with my latest VI but it went away after a couple of second.

I am out of idea on how to build my VI. I think the problem has to do with the way I am converting my commands to binary but all the options I tried do not seem to work. Could someone please help me out? I attached my VIs.

Thank you in advance

[crys]

Hi,

I am Christiane and this is my first time posting a question. I am not really sure how everything works. Also, I am very new with labview and testing boards. Therefore, I would probably not be able to specify exactly what device I have.

I am trying to test a USB device with Labview and an oscilloscope by sending 5 bytes to the board in binary. When I connect the board to my computer and run labview, everything seems to work. I do not get any error. However, when I connect my board with a coaxial cable to my oscilloscope, I am supposed to get square waves but do not get any. At some point, I was able to get a single pulse with my latest VI but it went away after a couple of second.

I am out of idea on how to build my VI. I think the problem has to do with the way I am converting my commands to binary but all the options I tried do not seem to work. Could someone please help me out? I attached my VIs.

Thank you in advance

[SnowMule]

What you've got here is a "race condition" - use dataflow (error cluster) through elements to enforce what code executes first.

The "Test mode 2" switch that reads the local variable from the "write out" field can execute before the "write out" string has been built. 

Another big thing that would help is to compartmentalize sections of code into subvi's.  Make one VI that builds the string, and another VI that writes the string.  Both of those SubVIs would be in the top-level VI's block diagram.

[NEWKlear]

Christiane,

Along with everything SnowMule said, you may want to run through this guide for getting started with LabVIEW.

http://www.ni.com/gettingstarted/labviewbasics/

You may want to use NI-VISA test panels in Measurement and Automation explorer to test your device aswell, and from within Measurement and Automation you will be able to see your device number.  If possible can you give us more information about what port you are trying to test the output on?

Regards,

J-Newkirk

Applications Engineer

National Instruments

http://www.ni.com/support

[crys]

Problem solved. Thank you!!