reading USB RAW devices in LabView

[zubin]

Hi, i have an ipod from which i want to read data. I made the device drivers using NI -VISA driver wizard and i am able to detect and write data to the ipod successfully from LabView as well as the VISA interactive control panel. Now I want to read data from the ipod but I get a time out error every time. I guess this is because there is nothing to read since the ipod is not sending data to the computer. I wanted to know how can I make the ipod send data to my computer so that I can have something to read in the LabView of the VISA interactive control panel. The moment I enable the RAW device drivers for the ipod, it disappears from windows (but NI - VISA and LabView still can see it) and so I cannot copy - paste a file etc. from the ipod to the computer to simulate a data going from the device the computer. So please anyone, let me know how reading of USB raw devicese can be done and how can i make my ipod transmit data to my computer !!! I am using BULK read and writes !!!

Thanks,

Zubin.

[Intaris]

Assigning a RAW driver to the device makes any software which relies on the standard driver cease working.

You may be able to use software such as "device monitor pro" to capture the USB protocol for sending and receiving data and then re-play this when the device is attached as a RAW device.  I don't know if this works, but it just might.

In either case, using the USB sniffer program will actually enable you to re-create the commands neccessary to implement the functionality you require.  You can leave the sniffer runinng when your program is communicating over VISA and see if the series of USB commands are the same as when the "normal" driver is installed.

Shane.

[zubin]

Hi,

Yes, I have been doing that. The sniffer programs I am using are USBTrace and NI - Spy. They both show success for viWrites but errors for viReads. The errors are always timeouts. Now I guess this is because there is no data going from the USB device (ipod) to the computer so there is nothing to read and so the timeout. So how can I simulate data going from the ipod to the computer so that viRead has something to read, especially when windows cannot "see" the device and so copy - pasting a file from the ipod to the computer is not possible to simulate data going from the device to the computer. Can you suggest a workaround for this??

Also, you mentioned USB Monitor Pro, where you said I can replay the read operations. Now the main problem is that there is no way I can think of triggering a data transfer from the ipod to the computer once the NI - VISA drivers are enabled ('cause windows cannot "see" the device anymore). So I wanted to know if there is any way I can write data to the bulk out point, and transfer it to the bulk in point and read the same data? Will I need some control words for this or some special commands? Please advice.

Thanks for your help.

Zubin. 

[Intaris]

Well a good sniffer program will sit BELOW the windows driver and will thus be able to do the SAME communication whether the "official" or the VISA driver is installed.

The communication between device and USB port is the same.

I haven't tried this with USB monitor pro, but I do think it's possible.

Shane.