[time-nuts] Did my Tbolt die ?

Bob Paddock bob.paddock at gmail.com
Sat Jul 17 09:09:01 EDT 2010

On Sat, Jul 17, 2010 at 5:17 AM, Neville Michie <namichie at gmail.com> wrote:

> I have had problems with TBolts on PCs. The COM port assignments seem to be
> a bit volatile,
> plug in a different mouse or other user and you may find the COM port has
> been assigned to it.
> I have never been able to confidently cope with this problem, I just keep
> hacking the
> system and sooner or later I get the COM port right with the right settings
> and all is well.
> There seem to be up to 3 layers to get right.
> This may be because I use USB to serial converters or just be inherent to
> the later Windows OS.
> cheers, Neville Michie

If you drill down under the Advanced button in the Serial Port Control panel
area you can reset the Windows COM port for a single port.
If you know the port is not in use, ignore the message that tells you that
it is in use, when you change the port number.

You can also search the Windows registry for the "COM Port
Arbitrator". It is a 256 binary bit map of the assigned, and the
next to be assigned, COM port.  That is where you reset the ever
incrementing COM port number.

If you are using a USB converter and want it to stay put, do the

This should work for non-FTDI devices, that have serial numbers, just match
the VID/PID.

>From FTDI Support:

What you will need to do is uninstall the driver for the FTDI device. Now
you will need to create a binary value in the registry by doing the

Go to START and select RUN

Type regedit in the filed and select ok to get into the registry

Add a REG_BINARY value called IgnoreHWSerNum to the registry and setting it
to 01.

This value is held in the registry key located at:
(Device VID, PID and interface}

For a default FTDI device ID (VID 0x0403, PID 0x6001), add the following
registry REG_BINARY value set to 01:


Now install the driver again. After this the com port should not increment.


James Leary
Support Engineer

If those don't help I can tell you the other darker places of the registry
to examine and poke at.  I had to make one of my programs "Idiot Proof".
Customers kept calling me up and asking me "What COM port do I have?".  I
always wanted to respond "How #$)*#)$ should I know?  It is your computer."
[It happened a lot, this group of customers were not Computer People.].
Instead I wrote my programs to always find the correct COM port for the
customer. I need to turn that into a DLL so other people can use it.

"Programming is a race between making programs Idiot Proof, so that any
Idiot can use it, and the Universe building bigger and better idiots.  The
Universe is winning."


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