Labview error using USB 6366 with USB fiber extender

[jk09]

HI,

I have two DAQ boards, USB 6366 and USB 6361. I need to use both in isolation from the computer on which I have labview 12 and the latest Daqmx installed, so I utilize an Icron USB hi-speed fiber extender, but there are some serious issues with labview and the USB 6366 only in this configuration. I can run both just fine with Measurement and Automation explorer, and I can run the USB 6361 just fine with labview as long as incorporate a work-around where I limit the USB data transfer request size to 1 on the last run of a DAQ task before stopping a labview VI with said DAQ task within.

By "limit the USB transfer rate to 1" I mean I create a physical channel property and set propery

Analog Input->General Properties->Advanced->Data Transfer and Memory->USB Data Transfer Request Size

to 1. Again, this only has to be done on the last run of the DAQmx task before the VI stops.

The problem with no solution is that the USB 6366 will only run correctly with labview upon the first running of a VI which utilizes the board. If I keep the VI running, the board can read and write indefinitely. This only works if the VI is that which calls the DAQ task, ie, if I run a VI within which a sub VI creates and runs a DAQ task using the USB 6366, the board only functions with the first call of the sub VI. If I then use the test panels in NI MAX, the board works just fine but will not run within labview. The work-around for the USB 6361 does not solve the problem for the 6366 This is clearly a software only issue, and I would appreciate a resolution. 

Thanks

[dsFlux]

Hi jk09,

Let's try a little more troubleshooting.

Are the DAQ boards able to run individually when connected directly to the computer's USB port one at a time instead of having them both connected via the Icron USB hi-speed fiber extender? Or is it the same issue when connected as such?

Are you being sure to clear both DAQmx tasks?

[jk09]

Hi David. Thanks so much for your response. 

Indeed, I have no problem running the DAQ boards without the Icron involved. When connected directly to the computer, they both run up to spec, connected at the same time or individually. The only problematic scenario involves the 6366 connected through the Icron, irrespective of the presence of the other DAQ board.  I can also run them each through a USB 2.0 full speed optical isolator, and they run reasonably well, but with a tremendous amount of lag. And, as I said, I can test both boards with no problems connected through the Icron using NI MAX test panels, even when the 6366 will not work in Labview.

I actually was previously utilizing my own home-made isolation method, but this was risky and causes the computer's USB bus to shut off intermittently.

Thanks again.