Re: [avrdude-dev] [bug #22234] WINDOWS version: HOWTO: Specify Serial Ports Larger than COM9

[Bob Paddock]

On Wed, 06 Feb 2008 08:28:37 -0500, Wouter van Gulik <address@hidden>  
wrote:

> Bob Paddock schreef:
> >  Usually COM ports above nine have happened because of plugging
> > in multiple USB Virtual Serial Port Devices; I'm
> > at COM33 on this machine right now :-( .  To Windows
> > each unique USB serial number looks like a new device,
> > so you get a new COM port number, even if it is the
> > same device/different unit.  Anyone know how to stop that??
>
> Well, you can clean up by removing them from the Device Manager. Use  
> this: http://support.microsoft.com/kb/315539 to view all hardware (even  
> not connected ones), and remove them.

While that is useful to fix the problem, thank you, I'd
like to prevent the problem in the first place.

In one of our products we connect a Mega128 via a FTDI FT245 USB
chip.  Each chip has a unique serial number.  As part of the
production test we plug each device in to a Windows test machine,
to make sure all of the USB section is working.  Windows sees
this new USB serial number as a completely new device, which
in this production test environment is not what we want to happen.
We want COM6, pick a number, and for it to remain that COM number,
no mater how many different USB serial numbers the test machine
sees.