USB / serial prob

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

Reply to
Nutz
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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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Reply to
Don McKenzie

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

Reply to
Nutz

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!).

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John Devereux
Reply to
John Devereux

ALter the properties manually assigning as you need. thats a right mouse button move

Reply to
atec 7 7

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

Reply to
Nutz

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.

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.
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RoRo
Reply to
Robert Roland

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:

formatting link

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.

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

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Don McKenzie

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Don McKenzie

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