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Error BFFF0072 or -1073807246, when trying to open VISA session

When I am trying to start a VISA session (my path is MAX>>Devices&Interfaces>>COM1) I am told that "The resource is valid, but VISA cannot currently access it." What does this mean? Should I do anything, or just wait? I get error BFFF0072 or -1073807246.
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This answer is on the NI site at

It sounds like the serial port you are trying to configure is in use already.  Make sure no other application is trying to access that port.
Mac 10.4
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Do you have Hyperterminal or any other application running that is accessing the serial port? Windows doesn't allow for multiple applications to access a serial port. If there is nothing obvious, check for a service that might be running in the background and maybe was installed as part of some software installation from the instrument vendor.
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I am also getting this error and I know for sure no application is using this serial port..becasue I can open and close this port from CVI application.

KB does not help much.

CVI 2010
LabVIEW 2011 SP1
Vision Builder AI 2011 SP1
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Hi Sheetal,

Without knowing more about what your program is doing, I am not sure what to suggest.  This KnowledgeBase has additional steps for troubleshooting this error.  If these steps do not help either, please provide additional information on when and where the error occurs and we can look into it further for you.  Also, if you run a program that only closes the resource (see picture below), does it then allow you to run it in your main program?

Have a great day!

Message Edited by Chris_R. on 05-30-2006 06:31 PM

Chris R.
Applications Engineer
National Instruments
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