On Thu, 22 Apr 2010 16:47:11 -0600, "Dwayne Reid" said:

> Something that concerns me is that I don't know how to ensure which 
> USB port is tethered to which comm port.  Because I have 3 identical 
> USB to serial adapters, its entirely possible that the comm port 
> numbers will move around between the 3 USB ports everytime the 
> computer is rebooted.

Hi Dwayne,

In my limited knowledge of Windows and USB-serial adapters:

A USB-serial adapter should grab the same comport number each time it is
plugged into the same USB port. The port numbers will not overlap. If
you plug adapter A into USB port 1 and it is assigned com4, it will
always be com4 if it is plugged into USB port 1. If you plug it into
another USB port it will grab the next never-used-before comport number,
but plugging it back into USB port 1 it will be com4 again. A different
USB-serial adapter will grab different comport numbers. Comport numbers
stay reserved "forever" for their mated adapter/USB port combinations.

So if you label the USB-serial adapters and the USB ports nothing should
change.

All of this works fine until you get into two-digit com numbers, then
you mileage may vary and you might consider going to the control panel
or if they are FTDI adapters they have a utility that cleans out the
registry entries and you start fresh.

Cheers,

Bob

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