Experience with USB RAW?

[kev_hib]

Hi again:)
I am now running VISA 3.1 as the driver for my custom USB device, and retrieving the interrupt data from the device. I was wondering if anyone had some experience on this area? The problem is that the system is too unstable.. The device always gets enumerated, and stays that way, but VISA will not always detect the interrupt transfers. I know this may be a hardware proplem, but I can't really understand that since I use the RS-232 and Hyperterminal to control that the device is sending properly.. The message indicates that the function sending the packet out the endpoint was successful.. Yet, the VISAIC only retrieves the interrupt data from time to time...(not like with timeout, now it either works for a session, or it doesn't) I h
ope someone has some tips:)

[JoshuaP]

The first thing I would suggest is to make sure you are using the latest version of NI-VISA, currently 3.2. Then try using some other utilities like USB Monitor to see what information is being transmitted. If your device never transmits the data then VISA is never going to read it. I have used VISA with several different devices and I have found it to be very reliable. Sometimes my firmware on the device might have been trouble some, but the problem was always in my firmware. The only other problem would be how you are trying to read the interrupts. Are you using a C or LabVIEW API?

Here are some examples that I have used in the past.
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=DC76651CD1522404E034080020E74861&p_node=DZ52363&p
_source=External (you can put the Wait on Event, Get USB Interrupt Data, and the first Close in a loop if you want to get the interrupts repeatedly)

Attached is a CVI example. Check out the different source files for different ways of getting the interrupts.

I hope this helps out some.

-Josh