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Why Am I Not Able to Open COM Port in Windows After Using DOS Serial Commands

Primary Software: Driver Software>>NI-Serial
Primary Software Version: 1.45
Primary Software Fixed Version: 1.5
Secondary Software: N/A
Hardware: Serial

Problem:
I open a DOS window in Windows 2000 and copy a file to a National Instruments serial port (i.e. COM8) with the command:

copy filename.txt com8

The printer attached to COM8 receives the data and I close the DOS window. Now when I try to open HyperTerminal and connect to COM8, I get the error:
     
      Unable to Open COM 8. Check Port Settings.

Why am I getting this error and How can I avoid this?

Solution:
The Windows serial driver version you are using does not close the serial port after copying the file so other programs are unable to obtain ownership of the port.

1. Upgrade to Windows 2000 service pack 4 or later.
   
2. Uninstall NI-Serial and reboot .
   
3. Cancel out of any hardware installation pop-ups.
   
4. Install NI-Serial 1.5 or later.
   
5. Reboot.

Note: Even if the DOS window is still open, programs should still be able to access the port since the copy command automatically closes the port after it is done.

Related Links:
Drivers and Updates: NI-Serial

Attachments:





Report Date: 09/24/2003
Last Updated: 11/05/2008
Document ID: 31N9H1WH

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