On 8/17/07, Xiaofan Chen <xiaofanc@gmail.com> wrote:
> On 8/16/07, William Couture <bcouture@gmail.com> wrote:
> > I keep running into the same problem whenever I use someone's
> > USB to serial converter:
> >
> > All chips, even "identical" chips from same manufactuer / lot,
> > have a unique *SERIAL NUMBER*.
> >
> > All the drivers check for *SERIAL NUMBER* as well as USB CID.
> >
> > If it sees a different *SERIAL NUMBER*, it insists on installing yet
> > another driver for the "new hardware".
> >
> > So, if you ever need to use a different "identical" piece of hardware,
> > drivers must be installed.
> >
> > If the driver installation messes up, that particular piece of "identical"
> > hardware can *NEVER* be used on that system, because of the bad
> > driver (the "driver remove" option never seems to work...)
> >
> > And, if you need to test, say 100 (or 1000...) pieces before they leave
> > the factory, *YOU NEED TO INSTALL THE DRIVER FOR EVERY UNIT
> > YOU TEST*
> >
> > Does anyone know who makes USB to serial chips without this
> > stupidity?
> >
>
> This is not stupid. This is a feature. To have a serial number is
> a good thing. If you have a USB device, if it does not have a
> serial number and you need to install the driver every time you
> install it to a different port, Windows will ask you for a driver.
> If it has a serial number, Windows will recognize it as a unique
> device and use the existing driver. This is the typical usage
> pattern of a USB device.
>
> Your case is not a typical usage of a USB device.
>
> Anyway, there might be a solution for your situation. Read this
> thread for Silabs CP210x.
> http://www.cygnal.org/ubb/Forum9/HTML/001323.html
>

Ok, you need to buy the book "USB Complete" 3rd Edition if you
want to do anything USB. Chapter 14 states the following for FTDI chips.

[quote]
"Avoiding COM-port Proliferation
Windows by default creates a new COM port for every device that
uses the VCP driver and has a serial number. If you're testing a
batch of devices, you can quickly reach the maximum of 256
COM ports. To free up some port numbers, use Windows'
Device Manager to uninstall devices you no longer need.
Another solution (for in-house testing environments only!) is to edit
ftdibus.inf to cause Windows to assign the VCP driver only to devices
attached to a specified physical port or ports, and to cause Windows
to create a single COM port for all of these devices, even if they
have different serial numbers. FTDI Chip provides an application note
with details about how to edit the INF file to accomplish this"
[/quote]

Regards,
Xiaofan
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