Comm ports change on there own

I will try and keep this short.  I was using the com 1 on my HP to key my radio.  That computer died and I got a new one that has no com ports so I got a USB to serial adapter and it seemed to work but then on its own it will key the radio 3 or 4 times then switch com ports on me.  I can reconfigure it and reboot and then it works (for a period of time) then does it again.  Any ideas?  Other devises are working fine on 2 other adapters but they have software that controls them where this one being used for push to talk on the radio (for digital communications) does not it is just relying on the voltage change from dtr dts and ground to key a small circuit that in turn keys the radio, when the voltage drops back to normal it unkeys the radio.  Thanks for taking the time to read this, and feel free to email direct to *** Email address is removed for privacy *** if you like.


Question Info

Last updated September 22, 2018 Views 4,473 Applies to:

Hi Tom WD0BFO,

Method 1: Install the Driver

1) Plug the cable into a USB port.
2) The “Welcome to the Found New Hardware Wizard”  or "Add New Hardware Wizard" should appear. If it doesn’t appear, go to next step.
3) Open Device Manager by doing the following:
   a) Click on “Start” and then “Control Panel.”
   b) Switch to Classic View (if in Category View).
   c) Double click on “System.”
   d) Select the Hardware tab.
   e) Press the “Device Manager” button.
4) Under “Ports (COM & LPT),” look for a USB Device entry with a yellow exclamation point '!' by it.
5) Right click on the USB Device and select “Update Driver.”
6) This should bring up the “Welcome to the Hardware Update Wizard.”
7) Ensure the product driver CD (included with package) is inserted in your CD-ROM drive.
8) Select the option, “Install the software automatically (Recommended).”
9) Press “Next.”

Method 2: Check the number of  the COM port being used by the adapter

1.    Right click on the "USB to Serial Port" and click on Properties.

2.    Click on the "Port Settings" tab. Click the "Advanced" button.

3.    Pull down the scrollbar on the bottom, left side and select COM 1, 2, 3 or 4 (NOTE: Choose one that does not say "in use" next to it). Click "OK."

4.    Click "OK" again. Notice that the device will show up as being on the same COM port that it was before, but will show up on the new port if you close the device manager and open it again.

5.    Close the device manager. You may have to run the software that came with your device to make it rescan the COM ports.

Also check the following settings:

·         Check the COM port used by the software you are using

·         Try a changing the COM port used by the adapter

·         Try plugging the adapter into a different USB port

·         Try installing the adapter on a different computer


Divya R – Microsoft Support.

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