error -1073807194 in VISA configure

[longzoo]

I have a USB device that I need use with COM drivers as well as D2XX. In order to switch between the two drivers a registry edit has to be made (which is no small feat for Windows 7 and the many levels of permissions). At times I have to switch from COM to D2XX, send some commands then switch back to COM. As expected, when i switch to D2XX i notice my COM port disappears from Computer Management then swiching back to COM it reappears. HOWEVER, after this point I can no longer run "VISA configure Serial Port (Serial Instr).vi" without the -1073807194 property node (arg 8).... error. 

I found in LAVA that arg 8 has to do with the flow control but regardless of the flow control setting i cannot make it pass. The only way to get VISA configure to run is to close LabVIEW COMPLETELY then reopen it. 

I also read that the arg 8 error can be caused by a hub so I moved the USB to the side of the computer rather than the monitor to no avail.

 

Can anyone tell me if LV is holding that port somehow, and how i can make it release?!? I have attempted to run VISA close as well as FT_Close_Device but nothing short of a complete closure of LabVIEW seems to work. 

Thanks,

Dave

[chris754]

I would hazard the LabVIEW loses track of the port when it disappears. Try using the VISA Find Resourse after switching to D2XX and see if it appears in the list. I would bet that it doesn't. I'm not sure how to force LabVIEW to refresh its resource list during runtime, LabVIEW seems to refresh it for me. I would make sure that the port is properly closed using VISA close before switching back and forth, I see that you did this, but maybe it was done in parallel or something? It's tough to tell without seeing code.

[viSci]

You can use a window utility called devcon.exe to restart a USB port.  That might force LabVIEW to refresh its VISA driver.  You can programmatically call devcon with the system exec.vi

[longzoo]

Thanks Chris, I manually ran Visa close several times but it seems to just latch up. 

[longzoo]

Thanks for the reply viSci, I  downloaded, installed and ran devcon.exe both manually (right click>>run as administrator) and with system exec.vi.  Either way when i run VISA configure...vi I still get a -1073807330 occurred at Property Node..... I seem to be missing something here

Edited August 11, 2014 by longzoo

[viSci]

Did you run devcon.exe with the 'restart' switch?

 

http://msdn.microsoft.com/en-us/library/windows/hardware/ff544807(v=vs.85).aspx

[longzoo]

hmmm, no i was running with the rescan swithc....let me give that a shot

NICE! thanks so much

[longzoo]

ding dang it...It's still latching up. I found that the version of devcon.exe i was using was a tad old and when i downloaded the new WDK (version 8.1) i was able to disable, enable, rescan and restart, however LabVIEW still won't allow me to use the port until i completely quit LV and come back in

Any other thoughts? 

[longzoo]

one other note...i noticed when i plugged another identical device in (same UART different serial number) and went to change the COM that the old COM number was "in use" as long as LabVIEW was still open. Regardless of restart, rescan, disable and enable cycles

[chris754]

Interesting. Are you sure that the Port still exists when you try to reconnect to it? Maybe Windows hasn't created it yet? Maybe you need a delay before you begin trying to connect. Other than that I'm not really sure what else could be going on.