Fix USB assignements. Was RE: [aprssig] NEW laptop for APRS with a Serial Port?

Dave Baxter dave at
Tue Apr 15 04:09:15 EDT 2008


You can "Fix" a USB adapter's serial port allocation in Control pannel,
System, Hardware, Device Manager.  Find the port it creates, and go to
it's Propteries, Port Settings, then the Advanced button.  There you can
assign and fix a COM port number to it, so next time you plug *That*
adapter into *That* USB port, it'll show up in the "same place".

Note:  USB devices have a unique ID number, much like a network card MAC
address.  So does the USB *Host* or Hub you connect it to.   If either
of those numbers change, Windows thinks it's another new device, so
it'll assign the next free com port to it.  Unless, you "Fix" it's
scheme, for each combination of device/USB port you can connect.

With a bit of careful planning, they can be very convenient and
predictable to use.

I know this to work with Win2k and XP, dunno about Vista.

Note too, that some popular mobile phone utility software seems to
"reserve" for it's own use, a huge block of COM port numbers.  The fix,
is to remove such tool's, sort out your virtual com port assignments,
then reinstall the phone utility program.

As someone else said, let's move ahead.  Serial (COM) ports are fine,
but to help move into the future, let's all move forwards.  After all,
Microchip of PIC fame, are producing PIC's with inbuilt USB (device)
functionality, and have all the app notes and examples regarding
migrating from physical COM ports, to USB connectivity.  If nothing
else, it allows you to shovel much more data back and forth, for
whatever purpose.  Other chip vendors are no doubt doing similar things.

All we need now, is a PC USB connector that doesn't fall out at
inopertune moments, or get damaged by "Abuse" of the cable...   That
currently in my eyes is a real problem, and something legacy serial
ports addressed with the screwjacks.   I know you cand get "Industrial"
In-Line secured USB connectors, but I've yet to see anything to reliably
secure a USB connector to the back of a PC, or other host, that itself
will not get dammaged by other "passing" hardware.

Cheers All..

Dave G0WBX.

> -----Original Message-----
> Subject: RE: [aprssig] NEW laptop for APRS with a Serial Port?
> I've used a couple of laptops with USB/serial adapters... 
> Some work, some work some of the time, some work/but change 
> com ports when they want to, some set com ports above 4, etc. 
> Ham radio is a hobby.... I don't want usb/serial to be a hobby<g>.
> Thanks,
> Kent
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