usb to serial problem? port is not released "Com4 is unavailable"

  • Thread starter Thread starter Mark
  • Start date Start date
M

Mark

I have an application that is using an InfraRed transmitter.
The transmitter is connected to USB port on my XP machine.
When after reboot the application is searching for the device it is
finding it on Com4 as it was originally installed.

Now when I start the application and application is starting to use the
device.
After while, the port4 becomes unavailable as I see from the message.
I close the application.
Check with Task Manager to insure there is no processes running to see
if port is being used.

Start application again. It can not use the port.
Message "Port unavailable" pops up again.

I move USB cable to another USB port.
Start application again. Make it search for port.
It finds the port.
Move cable again to old USB prt.
Make application search for port again.
It finds it now in old place.
For several iterations I can work, but then
port becomes unavailable again.

Anything I can do, instead of physically moving the cable back and
forth?

subject:usb to serial problem? port is not released "Com4 is
unavailable"
microsoft.public.windowsxp.hardware
 
I have an application that is using an InfraRed transmitter.
The transmitter is connected to USB port on my XP machine.
When after reboot the application is searching for the device it is
finding it on Com4 as it was originally installed.

Now when I start the application and application is starting to use the
device.
After while, the port4 becomes unavailable as I see from the message.
I close the application.
Check with Task Manager to insure there is no processes running to see
if port is being used.

Start application again. It can not use the port.
Message "Port unavailable" pops up again.

I move USB cable to another USB port.
Start application again. Make it search for port.
It finds the port.
Move cable again to old USB prt.
Make application search for port again.
It finds it now in old place.
For several iterations I can work, but then
port becomes unavailable again.

Anything I can do, instead of physically moving the cable back and
forth?

subject:usb to serial problem? port is not released "Com4 is
unavailable"
microsoft.public.windowsxp.hardware
Click to expand...

XP has a bug associated with assigning com port addresses to USB
devices. Every time the device is connected, it is assigned a
higher com port number. In the advanced section of the com port
setup in device manager when the device is connected, you can
just reassign the port number for the device to a lower port
number that you know is not in use, and ignore the windows
warning. I've done this with my USB/serial port adapter and XP
seems to remember the assigned com port after that. Check the
link below for some info.

http://www.modemsite.com/56k/xptip.asp
 
my device is not a modem. Does it matter?
How can I get an answer from Microsoft Windows Rep?
 
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