USB / serial prob

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I'm sure someone here can help with a problem I have......

I'm using an ATEN U-232A usb/serial converter for some bench work. I had the
converter working some time back but have since done a restore on my laptop
and the driver was removed.

Now its reinstalled it wants to connects as COM5/6 or 7, rather than the
COM3 or 4 that it used to use. How are the virtual com ports assigned? I go
into system hardware manager (XP home SP3) and under ports it shows COM3 & 4
as being in use - how to I delete or otherwise free them up?

I need COM3 or 4 as the software I need to use for the bench work is
restricted to these two ports.

Any advice appreciated.

thanks



Re: USB / serial prob
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XP home SP3:
you can basically force these to what you want:

Control Panel> System> Hardware>Device Manager> ports> select port >
properties> advanced> and if it says com5 then make it com 3.

it will change to port 3.

Don...






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Don McKenzie

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Re: USB / serial prob

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Hi Don - I should have known you would have replied!

I had tried as you suggested, under ports it only shows one device (the ATEN
converter), when I tried to change the port allocation it showed ports 3,4
as being in use. In use by what I asked.....?

I poked around and found the laptops internal PSTN modem was on com4. As a
get around I have disabled the modem and forced the Aten converter to com4
(it still showed com4 as "in use". It's now working ok but the solution
seems a little bodgy - I still cant find what is uing com3 (which I used to
use for the aten converter). Is it possible a virtual com port driver is
still running in the background somehow tying up com3??

cheers



Re: USB / serial prob

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Something USB has used that particular port at some time in the past, so
Windows marks the port as "in use" apparently just in case you ever plug
that device into the PC again.

You can change your existing driver/device to COM3, even though Windows
says that it's in use.  After you do, exit Device Manager and run it
again, and you'll see that the device is now using COM3.

Peter

Re: USB / serial prob

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Many thanks Peter, I'll go do it.



Re: USB / serial prob

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I seem to recall there is a menu selection in Device Mangler like
"show devices not present" or some such. Then all the com ports will
appear, even those allocated to unused devices. You can delete ones
you don't want so they are free for your device.

(Sorry to be so vague, I am not a regular windows user and don't have
easy access to an XP system at present. But I have used those ATEN
convertors!).

--

John Devereux

Re: USB / serial prob

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thanks John - Tom seems to have the rest of the info on this.



Re: USB / serial prob
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ALter the properties manually assigning as you need.
  thats a right mouse button move

Re: USB / serial prob
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To see all previous COM port assignments run the following in command line
window:
set devmgr_show_nonpresent_devices=1
set devmgr_show_details=1
devmgmt.msc
This will open your Device Manager, select View->Show Hidden Devices and have
fun - uninstall any old stuff.

Tom

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Awesome Tom, thanks. It also exposed a "gaopdx....."   virus server running
hidden away. The virus was removed some time back.

There were three other instances of the Aten driver running. Looks good now.

cheers
 



Re: USB / serial prob

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The ports are assigned incrementally from the lowest available number.
"Available" in this case means "has never been used". If a device has
used COM3, then COM3 will be permanently reserved for that particular
device.

In order to distiguish two identical devices, Windows uses the USB
serial number as a reference when it reserves ports. Some poorly
designed devices do not have a serial number programmed. Such devices
will get a new COM port assigned for each USB port they are plugged
into.

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John is on the right track. Here are the details:

1. Disconnect your USB device.
2. Start a Command Prompt.
3. In the Command Prompt, type these two lines:
    DEVMGR_SHOW_NONPRESENT_DEVICES=1
    devmgmt.msc
4. Device Manager will start.
5. In Device Manager, click "View" and select "Show hidden devices".
6. Reserved, but currently non-present ports will be shown in grey
olour.
7. Uninstall offending ports as needed, including your USB device's
port.
8. Connect your USB device. It should now get the lowest available COM
port number.
--
RoRo

Re: USB / serial prob

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Robert, it may have been a copy and paste problem, but the words "set"
and "start" are missing in your text, yet the space seems to be reserved
for it in the layout.

Below my message, is the text I have:

BTW, I wasn't aware of this technique, but I couldn't sort out why your
text didn't work, so I googled the string. I found a lot more at:
http://www.daniweb.com/forums/thread7700.html

Cheers Don...

=====================================================

Remove Hidden Devices

1. Open a Command Prompt.
2. Type "set DEVMGR_SHOW_DETAILS=1" (without quotation marks) and press
        Enter.
3. Type "set DEVMGR_SHOW_NONPRESENT_DEVICES=1" (without quotation marks)
and Press Enter.
4. Type "start devmgmt.msc" (without quotation marks) and click press Enter.
5. Click View. Click Show hidden devices.
6. Click "+" to expand devices, Unknown devices and USB devices.
7. Are there any devices and unknown devices (including grayed out
devices)? If so, please right click it and click Uninstall them.

=====================================================

--
Don McKenzie

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